Daniel Jarosz, Ph.D., is an Assistant Professor in the Departments of Chemical & Systems Biology and Developmental Biology at Stanford University. He received his B.S. in Chemistry and Biochemistry from the University of Washington and then moved to Massachusetts Institute of Technology for his PhD, where he investigated mechanisms of replication and mutagenesis in the laboratory of Dr. Graham Walker. Following his graduation in 2007, Dr. Jarosz pursued postdoctoral training at the Whitehead Institute with Dr. Susan Lindquist, a pioneer in the field of protein folding. In 2013 Dr. Jarosz established his independent group at Stanford University, where his research is focused on molecular mechanisms that contribute to robustness and evolvability. His work employs multidisciplinary systems approaches ranging from chemical biology to quantitative genetics to understand how these mechanisms contribute to evolution, disease, and development. Dr. Jarosz has received a number of distinctions including being named a Searle Scholar and Kimmel Scholar. He has also received a Science and Engineering Fellowship from the David and Lucile Packard Foundation, a Director's New Innovator Award from the NIH, a CAREER award from the NSF, a Pathway to Independence Award from the NIH, and a fellowship from the Damon Runyon Cancer Research Foundation.
Honors & Awards
Award for Research in Biological Mechanisms of Aging, Glenn Foundation (2016)
New Innovator, NIH (2015-present)
Science and Engineering Fellow, David and Lucile Packard Foundation (2015-present)
Kimmel Scholar, Sidney Kimmel Foundation for Cancer Research (2015-present)
NSF-CAREER Award, National Science Foundation (2015-present)
Searle Scholar, Kinship Foundation/Chicago Community Trust (2014-present)
Pathway to Independence (K99/R00) Award, National Institutes of Health (2011-present)
Postdoctoral Fellowship, Damon Runyon Cancer Research Foundation (2008-2010)
Transition School/Early Entrance Program, University of Washington (1996-2001)
Postdoctoral, Whitehead Institute for Biomedical Research, Genetics and Cell Biology (2012)
Ph.D., MIT, Biological Chemistry (2007)
B.S., University of Washington, Chemistry and Biochemistry (2001)
Current Research and Scholarly Interests
Survival in changing environments requires the acquisition of new heritable traits. However, mechanisms that safeguard the fidelity of DNA replication often limit the source of such novelty to relatively modest changes in the genetic code. Thus, the acquisition of new forms and functions is thought to be driven by rare variants that occur at random, and are enriched during times of stress. We have begun to study an intriguing alternative hypothesis: that intrinsic links between protein folding and virtually every biological trait provide multiple avenues through which environmental stress can directly elicit heritable variation that drives evolution, disease, and development.
Our aim is to identify and characterize these mechanisms at the molecular level, integrating our findings to gain insight into the interplay among genetic variation, phenotypic diversity, and environmental fluctuations in complex cellular systems. Much of our work centers on the specific influence of molecular chaperones, proteins that help other proteins fold. Other projects focus on the induction of epigenetic variation that can be passed from one generation to another via self-perpetuating changes in protein conformation. Our work employs multidisciplinary approaches including biochemistry, genome-scale analyses, high-throughput screening methodologies, live cell imaging, microfluidics, and quantitative genetic techniques. Ultimately we seek to not only to understand mechanisms that link environmental stress to the acquisition of biological novelty, but also to identify means of manipulating them for therapeutic benefit and harnessing their power to engineer synthetic signaling networks.
- Chemical and Systems Biology Bootcamp
CSB 201 (Aut)
Independent Studies (11)
- Directed Investigation
BIOE 392 (Sum)
- Directed Reading in Chemical and Systems Biology
CSB 299 (Win, Spr)
- Directed Reading in Developmental Biology
DBIO 299 (Win, Spr)
- Graduate Research
CSB 399 (Aut, Win, Spr, Sum)
- Graduate Research
DBIO 399 (Aut, Win, Spr, Sum)
- Medical Scholars Research
CSB 370 (Win, Spr)
- Medical Scholars Research
DBIO 370 (Win, Spr)
- Out-of-Department Advanced Research Laboratory in Experimental Biology
BIO 199X (Aut, Win, Spr)
- Out-of-Department Graduate Research
BIO 300X (Aut, Win, Spr, Sum)
- Undergraduate Research
CSB 199 (Aut, Win, Spr, Sum)
- Undergraduate Research
DBIO 199 (Win, Spr)
- Directed Investigation
- Prior Year Courses
Postdoctoral Faculty Sponsor
Anupam Chakravarty, David Garcia, Christopher Jakobson, Shady Saad, Jing Lin Xie, Rebecca Zabinsky
Doctoral Dissertation Reader (AC)
. Ei Cho, Michael Guernsey, Samuel Kimmey, Opher Kornfeld, Michael Melfi, Kelsey Roberts
Doctoral Dissertation Advisor (AC)
James Byers, Yiwen Chen, Raymond Futia, Zachary Harvey, Alan Itakura, Jonathan Mares, Richard She
Comprehensive and quantitative mapping of RNA-protein interactions across a transcribed eukaryotic genome
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2017; 114 (14): 3619-3624
RNA-binding proteins (RBPs) control the fate of nearly every transcript in a cell. However, no existing approach for studying these posttranscriptional gene regulators combines transcriptome-wide throughput and biophysical precision. Here, we describe an assay that accomplishes this. Using commonly available hardware, we built a customizable, open-source platform that leverages the inherent throughput of Illumina technology for direct biophysical measurements. We used the platform to quantitatively measure the binding affinity of the prototypical RBP Vts1 for every transcript in the Saccharomyces cerevisiae genome. The scale and precision of these measurements revealed many previously unknown features of this well-studied RBP. Our transcribed genome array (TGA) assayed both rare and abundant transcripts with equivalent proficiency, revealing hundreds of low-abundance targets missed by previous approaches. These targets regulated diverse biological processes including nutrient sensing and the DNA damage response, and implicated Vts1 in de novo gene "birth." TGA provided single-nucleotide resolution for each binding site and delineated a highly specific sequence and structure motif for Vts1 binding. Changes in transcript levels in vts1Δ cells established the regulatory function of these binding sites. The impact of Vts1 on transcript abundance was largely independent of where it bound within an mRNA, challenging prevailing assumptions about how this RBP drives RNA degradation. TGA thus enables a quantitative description of the relationship between variant RNA structures, affinity, and in vivo phenotype on a transcriptome-wide scale. We anticipate that TGA will provide similarly comprehensive and quantitative insights into the function of virtually any RBP.
View details for DOI 10.1073/pnas.1618370114
View details for Web of Science ID 000398159000041
View details for PubMedID 28325876
A common bacterial metabolite elicits prion-based bypass of glucose repression.
Robust preference for fermentative glucose metabolism has motivated domestication of the budding yeast Saccharomyces cerevisiae. This program can be circumvented by a protein-based genetic element, the [GAR(+)] prion, permitting simultaneous metabolism of glucose and other carbon sources. Diverse bacteria can elicit yeast cells to acquire [GAR(+)], although the molecular details of this interaction remain unknown. Here we identify the common bacterial metabolite lactic acid as a strong [GAR(+)] inducer. Transient exposure to lactic acid caused yeast cells to heritably circumvent glucose repression. This trait had the defining genetic properties of [GAR(+)], and did not require utilization of lactic acid as a carbon source. Lactic acid also induced [GAR(+)]-like epigenetic states in fungi that diverged from S. cerevisiae ~200 million years ago, and in which glucose repression evolved independently. To our knowledge, this is the first study to uncover a bacterial metabolite with the capacity to potently induce a prion.
View details for DOI 10.7554/eLife.17978
View details for PubMedID 27906649
View details for PubMedCentralID PMC5132342
Intrinsically Disordered Proteins Drive Emergence and Inheritance of Biological Traits.
2016; 167 (2): 369-381 e12
Prions are a paradigm-shifting mechanism of inheritance in which phenotypes are encoded by self-templating protein conformations rather than nucleic acids. Here, we examine the breadth of protein-based inheritance across the yeast proteome by assessing the ability of nearly every open reading frame (ORF; ∼5,300 ORFs) to induce heritable traits. Transient overexpression of nearly 50 proteins created traits that remained heritable long after their expression returned to normal. These traits were beneficial, had prion-like patterns of inheritance, were common in wild yeasts, and could be transmitted to naive cells with protein alone. Most inducing proteins were not known prions and did not form amyloid. Instead, they are highly enriched in nucleic acid binding proteins with large intrinsically disordered domains that have been widely conserved across evolution. Thus, our data establish a common type of protein-based inheritance through which intrinsically disordered proteins can drive the emergence of new traits and adaptive opportunities.
View details for DOI 10.1016/j.cell.2016.09.017
View details for PubMedID 27693355
View details for PubMedCentralID PMC5066306
Hsp90: A Global Regulator of the Genotype-to-Phenotype Map in Cancers.
Advances in cancer research
2016; 129: 225-247
Cancer cells have the unusual capacity to limit the cost of the mutation load that they harbor and simultaneously harness its evolutionary potential. This property fuels drug resistance, a key failure mode in oncogene-directed therapy. However, the factors that regulate this capacity might also provide an Achilles' heel that could be exploited therapeutically. Recently, insight has come from a seemingly distant field: protein folding. It is now clear that protein homeostasis broadly supports malignancy and fuels the rapid evolution of drug resistance. Among protein homeostatic mechanisms that influence cancer biology, the essential ATP-driven molecular chaperone heat-shock protein 90 (Hsp90) is especially important. Hsp90 catalyzes folding of many proteins that regulate growth and development. These "client" kinases, transcription factors, and ubiquitin ligases often play critical roles in human disease, especially cancer. Studies in a wide range of systems-from single-celled organisms to human tumor samples-suggest that Hsp90 can broadly reshape the map between genotype and phenotype, acting as a "capacitor" and "potentiator" of genetic variation. Indeed, it has likely done so to such a degree that it has left an impress on diverse genome sequences. Hsp90 can constitute as much as 5% of total protein in transformed cells and increased levels of heat-shock activation correlate with poor prognosis in breast cancer. These findings and others have motivated a flurry of interest in Hsp90 inhibitors as cancer therapeutics, which have met with rather limited success as single agents, but may eventually prove invaluable in limiting the emergence of resistance to other chemotherapeutics, both genotoxic and molecularly targeted. Here, we provide an overview of Hsp90 function, review its relationship to genetic variation and the evolution of new traits, and discuss the importance of these findings for cancer biology and future efforts to drug this pathway.
View details for DOI 10.1016/bs.acr.2015.11.001
View details for PubMedID 26916007
Cross-kingdom chemical communication drives a heritable, mutually beneficial prion-based transformation of metabolism.
2014; 158 (5): 1083-1093
In experimental science, organisms are usually studied in isolation, but in the wild, they compete and cooperate in complex communities. We report a system for cross-kingdom communication by which bacteria heritably transform yeast metabolism. An ancient biological circuit blocks yeast from using other carbon sources in the presence of glucose. [GAR(+)], a protein-based epigenetic element, allows yeast to circumvent this "glucose repression" and use multiple carbon sources in the presence of glucose. Some bacteria secrete a chemical factor that induces [GAR(+)]. [GAR(+)] is advantageous to bacteria because yeast cells make less ethanol and is advantageous to yeast because their growth and long-term viability is improved in complex carbon sources. This cross-kingdom communication is broadly conserved, providing a compelling argument for its adaptive value. By heritably transforming growth and survival strategies in response to the selective pressures of life in a biological community, [GAR(+)] presents a unique example of Lamarckian inheritance.
View details for DOI 10.1016/j.cell.2014.07.025
View details for PubMedID 25171409
An Evolutionarily Conserved Prion-like Element Converts Wild Fungi from Metabolic Specialists to Generalists.
2014; 158 (5): 1072-1082
[GAR(+)] is a protein-based element of inheritance that allows yeast (Saccharomyces cerevisiae) to circumvent a hallmark of their biology: extreme metabolic specialization for glucose fermentation. When glucose is present, yeast will not use other carbon sources. [GAR(+)] allows cells to circumvent this "glucose repression." [GAR(+)] is induced in yeast by a factor secreted by bacteria inhabiting their environment. We report that de novo rates of [GAR(+)] appearance correlate with the yeast's ecological niche. Evolutionarily distant fungi possess similar epigenetic elements that are also induced by bacteria. As expected for a mechanism whose adaptive value originates from the selective pressures of life in biological communities, the ability of bacteria to induce [GAR(+)] and the ability of yeast to respond to bacterial signals have been extinguished repeatedly during the extended monoculture of domestication. Thus, [GAR(+)] is a broadly conserved adaptive strategy that links environmental and social cues to heritable changes in metabolism.
View details for DOI 10.1016/j.cell.2014.07.024
View details for PubMedID 25171408
Cryptic Variation in Morphological Evolution: HSP90 as a Capacitor for Loss of Eyes in Cavefish
2013; 342 (6164): 1372-1375
In the process of morphological evolution, the extent to which cryptic, preexisting variation provides a substrate for natural selection has been controversial. We provide evidence that heat shock protein 90 (HSP90) phenotypically masks standing eye-size variation in surface populations of the cavefish Astyanax mexicanus. This variation is exposed by HSP90 inhibition and can be selected for, ultimately yielding a reduced-eye phenotype even in the presence of full HSP90 activity. Raising surface fish under conditions found in caves taxes the HSP90 system, unmasking the same phenotypic variation as does direct inhibition of HSP90. These results suggest that cryptic variation played a role in the evolution of eye loss in cavefish and provide the first evidence for HSP90 as a capacitor for morphological evolution in a natural setting.
View details for DOI 10.1126/science.1240276
View details for Web of Science ID 000328196000051
View details for PubMedID 24337296
Prions are a common mechanism for phenotypic inheritance in wild yeasts
2012; 482 (7385): 363-U1507
The self-templating conformations of yeast prion proteins act as epigenetic elements of inheritance. Yeast prions might provide a mechanism for generating heritable phenotypic diversity that promotes survival in fluctuating environments and the evolution of new traits. However, this hypothesis is highly controversial. Prions that create new traits have not been found in wild strains, leading to the perception that they are rare 'diseases' of laboratory cultivation. Here we biochemically test approximately 700 wild strains of Saccharomyces for [PSI(+)] or [MOT3(+)], and find these prions in many. They conferred diverse phenotypes that were frequently beneficial under selective conditions. Simple meiotic re-assortment of the variation harboured within a strain readily fixed one such trait, making it robust and prion-independent. Finally, we genetically screened for unknown prion elements. Fully one-third of wild strains harboured them. These, too, created diverse, often beneficial phenotypes. Thus, prions broadly govern heritable traits in nature, in a manner that could profoundly expand adaptive opportunities.
View details for DOI 10.1038/nature10875
View details for Web of Science ID 000300287100038
View details for PubMedID 22337056
Hsp90 and Environmental Stress Transform the Adaptive Value of Natural Genetic Variation
2010; 330 (6012): 1820-1824
How can species remain unaltered for long periods yet also undergo rapid diversification? By linking genetic variation to phenotypic variation via environmental stress, the Hsp90 protein-folding reservoir might promote both stasis and change. However, the nature and adaptive value of Hsp90-contingent traits remain uncertain. In ecologically and genetically diverse yeasts, we find such traits to be both common and frequently adaptive. Most are based on preexisting variation, with causative polymorphisms occurring in coding and regulatory sequences alike. A common temperature stress alters phenotypes similarly. Both selective inhibition of Hsp90 and temperature stress increase correlations between genotype and phenotype. This system broadly determines the adaptive value of standing genetic variation and, in so doing, has influenced the evolution of current genomes.
View details for DOI 10.1126/science.1195487
View details for Web of Science ID 000285603700040
View details for PubMedID 21205668
Protein Homeostasis and the Phenotypic Manifestation of Genetic Diversity: Principles and Mechanisms
ANNUAL REVIEW OF GENETICS, VOL 44
2010; 44: 189-216
Changing a single nucleotide in a genome can have profound consequences under some conditions, but the same change can have no consequences under others. Indeed, organisms can be surprisingly robust to environmental and genetic perturbations. Yet, the mechanisms underlying such robustness are controversial. Moreover, how they might affect evolutionary change remains enigmatic. Here, we review the recently appreciated central role of protein homeostasis in buffering and potentiating genetic variation and discuss how these processes mediate the critical influence of the environment on the relationship between genotype and phenotype. Deciphering how robustness emerges from biological organization and the mechanisms by which it is overcome in changing environments will lead to a more complete understanding of both fundamental evolutionary processes and diverse human diseases.
View details for DOI 10.1146/annurev.genet.40.110405.090412
View details for Web of Science ID 000286042600009
View details for PubMedID 21047258
A single amino acid governs enhanced activity of DinB DNA polymerases on damaged templates
2006; 439 (7073): 225-228
Translesion synthesis (TLS) by Y-family DNA polymerases is a chief mechanism of DNA damage tolerance. Such TLS can be accurate or error-prone, as it is for bypass of a cyclobutane pyrimidine dimer by DNA polymerase eta (XP-V or Rad30) or bypass of a (6-4) TT photoproduct by DNA polymerase V (UmuD'2C), respectively. Although DinB is the only Y-family DNA polymerase conserved among all domains of life, the biological rationale for this striking conservation has remained enigmatic. Here we report that the Escherichia coli dinB gene is required for resistance to some DNA-damaging agents that form adducts at the N2-position of deoxyguanosine (dG). We show that DinB (DNA polymerase IV) catalyses accurate TLS over one such N2-dG adduct (N2-furfuryl-dG), and that DinB and its mammalian orthologue, DNA polymerase kappa, insert deoxycytidine (dC) opposite N2-furfuryl-dG with 10-15-fold greater catalytic proficiency than opposite undamaged dG. We also show that mutating a single amino acid, the 'steric gate' residue of DinB (Phe13 --> Val) and that of its archaeal homologue Dbh (Phe12 --> Ala), separates the abilities of these enzymes to perform TLS over N2-dG adducts from their abilities to replicate an undamaged template. We propose that DinB and its orthologues are specialized to catalyse relatively accurate TLS over some N2-dG adducts that are ubiquitous in nature, that lesion bypass occurs more efficiently than synthesis on undamaged DNA, and that this specificity may be achieved at least in part through a lesion-induced conformational change.
View details for DOI 10.1038/nature04318
View details for Web of Science ID 000234538400045
View details for PubMedID 16407906
- Old moms say, no Sir. Science (New York, N.Y.) 2017; 355 (6330): 1126-1127
- Pernicious pathogens or expedient elements of inheritance: the significance of yeast prions. PLoS pathogens 2014; 10 (4)
- Pernicious pathogens or expedient elements of inheritance: the significance of yeast prions. PLoS pathogens 2014; 10 (4)
- Rebels with a cause: molecular features and physiological consequences of yeast prions FEMS YEAST RESEARCH 2014; 14 (1): 136-147
HSP90 at the hub of protein homeostasis: emerging mechanistic insights
NATURE REVIEWS MOLECULAR CELL BIOLOGY
2010; 11 (7): 515-528
Heat shock protein 90 (HSP90) is a highly conserved molecular chaperone that facilitates the maturation of a wide range of proteins (known as clients). Clients are enriched in signal transducers, including kinases and transcription factors. Therefore, HSP90 regulates diverse cellular functions and exerts marked effects on normal biology, disease and evolutionary processes. Recent structural and functional analyses have provided new insights on the transcriptional and biochemical regulation of HSP90 and the structural dynamics it uses to act on a diverse client repertoire. Comprehensive understanding of how HSP90 functions promises not only to provide new avenues for therapeutic intervention, but to shed light on fundamental biological questions.
View details for DOI 10.1038/nrm2918
View details for Web of Science ID 000280076000016
View details for PubMedID 20531426
A DinB variant reveals diverse physiological consequences of incomplete TLS extension by a Y-family DNA polymerase
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2009; 106 (50): 21137-21142
The only Y-family DNA polymerase conserved among all domains of life, DinB and its mammalian ortholog pol kappa, catalyzes proficient bypass of damaged DNA in translesion synthesis (TLS). Y-family DNA polymerases, including DinB, have been implicated in diverse biological phenomena ranging from adaptive mutagenesis in bacteria to several human cancers. Complete TLS requires dNTP insertion opposite a replication blocking lesion and subsequent extension with several dNTP additions. Here we report remarkably proficient TLS extension by DinB from Escherichia coli. We also describe a TLS DNA polymerase variant generated by mutation of an evolutionarily conserved tyrosine (Y79). This mutant DinB protein is capable of catalyzing dNTP insertion opposite a replication-blocking lesion, but cannot complete TLS, stalling three nucleotides after an N(2)-dG adduct. Strikingly, expression of this variant transforms a bacteriostatic DNA damaging agent into a bactericidal drug, resulting in profound toxicity even in a dinB(+) background. We find that this phenomenon is not exclusively due to a futile cycle of abortive TLS followed by exonucleolytic reversal. Rather, gene products with roles in cell death and metal homeostasis modulate the toxicity of DinB(Y79L) expression. Together, these results indicate that DinB is specialized to perform remarkably proficient insertion and extension on damaged DNA, and also expose unexpected connections between TLS and cell fate.
View details for DOI 10.1073/pnas.0907257106
View details for Web of Science ID 000272795300025
View details for PubMedID 19948952
- Song: SOS (To the Tune of ABBA's "SOS"). Biochemistry and molecular biology education 2009; 37 (5): 316-?
UmuD and RecA directly modulate the mutagenic potential of the Y family DNA polymerase DinB
2007; 28 (6): 1058-1070
DinB is the only translesion Y family DNA polymerase conserved among bacteria, archaea, and eukaryotes. DinB and its orthologs possess a specialized lesion bypass function but also display potentially deleterious -1 frameshift mutagenic phenotypes when overproduced. We show that the DNA damage-inducible proteins UmuD(2) and RecA act in concert to modulate this mutagenic activity. Structural modeling suggests that the relatively open active site of DinB is enclosed by interaction with these proteins, thereby preventing the template bulging responsible for -1 frameshift mutagenesis. Intriguingly, residues that define the UmuD(2)-interacting surface on DinB statistically covary throughout evolution, suggesting a driving force for the maintenance of a regulatory protein-protein interaction at this site. Together, these observations indicate that proteins like RecA and UmuD(2) may be responsible for managing the mutagenic potential of DinB orthologs throughout evolution.
View details for DOI 10.1016/j.molcel.2007.10.025
View details for Web of Science ID 000252170000012
View details for PubMedID 18158902
DNA polymerase V allows bypass of toxic guanine oxidation products in vivo
JOURNAL OF BIOLOGICAL CHEMISTRY
2007; 282 (17): 12741-12748
Reactive oxygen and nitrogen radicals produced during metabolic processes, such as respiration and inflammation, combine with DNA to form many lesions primarily at guanine sites. Understanding the roles of the polymerases responsible for the processing of these products to mutations could illuminate molecular mechanisms that correlate oxidative stress with cancer. Using M13 viral genomes engineered to contain single DNA lesions and Escherichia coli strains with specific polymerase (pol) knockouts, we show that pol V is required for efficient bypass of structurally diverse, highly mutagenic guanine oxidation products in vivo. We also find that pol IV participates in the bypass of two spiroiminodihydantoin lesions. Furthermore, we report that one lesion, 5-guanidino-4-nitroimidazole, is a substrate for multiple SOS polymerases, whereby pol II is necessary for error-free replication and pol V for error-prone replication past this lesion. The results spotlight a major role for pol V and minor roles for pol II and pol IV in the mechanism of guanine oxidation mutagenesis.
View details for DOI 10.1074/jbc.M700575200
View details for Web of Science ID 000245942800044
View details for PubMedID 17322566
Proficient and accurate bypass of persistent DNA lesions by DinB DNA polymerases
2007; 6 (7): 817-822
Despite nearly universal conservation through evolution, the precise function of the DinB/pol kappa branch of the Y-family of DNA polymerases has remained unclear. Recent results suggest that DinB orthologs from all domains of life proficiently bypass replication blocking lesions that may be recalcitrant to DNA repair mechanisms. Like other translesion DNA polymerases, the error frequency of DinB and its orthologs is higher than the DNA polymerases that replicate the majority of the genome. However, recent results suggest that some Y-family polymerases, including DinB and pol kappa, bypass certain types of DNA damage with greater proficiency than an undamaged template. Moreover, they do so relatively accurately. The ability to employ this mechanism to manage DNA damage may be especially important for types of DNA modification that elude repair mechanisms. For these lesions, translesion synthesis may represent a more important line of defense than for other types of DNA damage that are more easily dealt with by other more accurate mechanisms.
View details for Web of Science ID 000245577800012
View details for PubMedID 17377496
Y-family DNA polymerases in Escherichia coli
TRENDS IN MICROBIOLOGY
2007; 15 (2): 70-77
The observation that mutations in the Escherichia coli genes umuC+ and umuD+ abolish mutagenesis induced by UV light strongly supported the counterintuitive notion that such mutagenesis is an active rather than passive process. Genetic and biochemical studies have revealed that umuC+ and its homolog dinB+ encode novel DNA polymerases with the ability to catalyze synthesis past DNA lesions that otherwise stall replication--a process termed translesion synthesis (TLS). Similar polymerases have been identified in nearly all organisms, constituting a new enzyme superfamily. Although typically viewed as unfaithful copiers of DNA, recent studies suggest that certain TLS polymerases can perform proficient and moderately accurate bypass of particular types of DNA damage. Moreover, various cellular factors can modulate their activity and mutagenic potential.
View details for DOI 10.1016/j.tim.2006.12.004
View details for Web of Science ID 000244535900004
View details for PubMedID 17207624
Y-family DNA polymerases respond to DNA damage-independent inhibition of replication fork progression
2006; 25 (4): 868-879
In Escherichia coli, the Y-family DNA polymerases Pol IV (DinB) and Pol V (UmuD2'C) enhance cell survival upon DNA damage by bypassing replication-blocking DNA lesions. We report a unique function for these polymerases when DNA replication fork progression is arrested not by exogenous DNA damage, but with hydroxyurea (HU), thereby inhibiting ribonucleotide reductase, and bringing about damage-independent DNA replication stalling. Remarkably, the umuC122::Tn5 allele of umuC, dinB, and certain forms of umuD gene products endow E. coli with the ability to withstand HU treatment (HUR). The catalytic activities of the UmuC122 and DinB proteins are both required for HUR. Moreover, the lethality brought about by such stalled replication forks in the wild-type derivatives appears to proceed through the toxin/antitoxin pairs mazEF and relBE. This novel function reveals a role for Y-family polymerases in enhancing cell survival under conditions of nucleotide starvation, in addition to their established functions in response to DNA damage.
View details for DOI 10.1038/sj.emboj.7600986
View details for Web of Science ID 000236225000020
View details for PubMedID 16482223
Characterization of Escherichia coli translesion synthesis polymerases and their accessory factors
DNA REPAIR, PT A
2006; 408: 318-340
Members of the Y family of DNA polymerases are specialized to replicate lesion-containing DNA. However, they lack 3'-5' exonuclease activity and have reduced fidelity compared to replicative polymerases when copying undamaged templates, and thus are potentially mutagenic. Y family polymerases must be tightly regulated to prevent aberrant mutations on undamaged DNA while permitting replication only under conditions of DNA damage. These polymerases provide a mechanism of DNA damage tolerance, confer cellular resistance to a variety of DNA-damaging agents, and have been implicated in bacterial persistence. The Y family polymerases are represented in all domains of life. Escherichia coli possesses two members of the Y family, DNA pol IV (DinB) and DNA pol V (UmuD'(2)C), and several regulatory factors, including those encoded by the umuD gene that influence the activity of UmuC. This chapter outlines procedures for in vivo and in vitro analysis of these proteins. Study of the E. coli Y family polymerases and their accessory factors is important for understanding the broad principles of DNA damage tolerance and mechanisms of mutagenesis throughout evolution. Furthermore, study of these enzymes and their role in stress-induced mutagenesis may also give insight into a variety of phenomena, including the growing problem of bacterial antibiotic resistance.
View details for DOI 10.1016/S0076-6879(06)08020-7
View details for Web of Science ID 000238224100020
View details for PubMedID 16793378