Jakobson,Christopher Matthew
Basic Life Research Scientist, Chemical and Systems Biology Operations
All Publications
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The Hsp90 molecular chaperone as a global modifier of the genotype-phenotype-fitness map: An evolutionary perspective.
Journal of molecular biology
2024: 168846
Abstract
Global modifier genes influence the mapping of genotypes onto phenotypes and fitness through their epistatic interactions with genetic variants on a massive scale. The first such factor to be identified, Hsp90, is a highly conserved molecular chaperone that plays a central role in protein homeostasis. Hsp90 is a "hub of hubs" that chaperones proteins engaged in many key cellular and developmental regulatory networks. These clients, which are enriched in kinases, transcription factors, and E3 ubiquitin ligases, drive diverse cellular functions and are themselves highly connected. By contrast to many other hub proteins, the abundance and activity of Hsp90 changes substantially in response to shifting environmental conditions. As a result, Hsp90 modifies the functional impact of many genetic variants simultaneously in a manner that depends on environmental stress. Studies in diverse organisms suggest that this coupling between Hsp90 function and challenging environments exerts a substantial impact on what parts of the genome are visible to natural selection, expanding adaptive opportunities when most needed. In this Perspective, we explore the multifaceted role of Hsp90 as global modifier of the genotype-phenotype-fitness map as well as its implications for evolution in nature and the clinic.
View details for DOI 10.1016/j.jmb.2024.168846
View details for PubMedID 39481633
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Hsp90 shapes adaptation by controlling the fitness consequences of regulatory variation.
bioRxiv : the preprint server for biology
2023
Abstract
The essential stress-responsive chaperone Hsp90 impacts development and adaptation from microbes to humans. Yet despite evidence of its role in evolution, pathogenesis, and oncogenic transformation, the molecular mechanisms by which Hsp90 alters the consequences of mutations remain vigorously debated. Here we exploit the power of nucleotide-resolution genetic mapping in Saccharomyces cerevisiae to uncover more than 1,000 natural variant-to-phenotype associations governed by this molecular chaperone. Strikingly, Hsp90 more frequently modified the phenotypic effects of cis-regulatory variation than variants that altered protein sequence. Moreover, these interactions made the largest contribution to Hsp90-dependent heredity. Nearly all interacting variants-both regulatory and protein-coding-fell within clients of Hsp90 or targets of its direct binding partners. Hsp90 activity affected mutations in evolutionarily young genes, segmental deletions, and heterozygotes, highlighting its influence on variation central to evolutionary novelty. Reconciling the diverse epistatic effects of this chaperone, synthetic transcriptional regulation and reconstructions of natural alleles by genome editing revealed a central role for Hsp90 in regulating the fundamental relationship between activity and phenotype. Our findings establish that non-coding variation is a core driver of Hsp90's influence on heredity, offering a mechanistic explanation for the chaperone's strong effects on evolution and development across species.
View details for DOI 10.1101/2023.10.30.564848
View details for PubMedID 37961536
View details for PubMedCentralID PMC10634948
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Metabolites control stress granule disassembly.
Nature cell biology
2021
View details for DOI 10.1038/s41556-021-00768-w
View details for PubMedID 34616025
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A prion accelerates proliferation at the expense of lifespan.
eLife
2021; 10
Abstract
In fluctuating environments, switching between different growth strategies, such as those affecting cell size and proliferation, can be advantageous to an organism. Trade-offs arise, however. Mechanisms that aberrantly increase cell size or proliferation-such as mutations or chemicals that interfere with growth regulatory pathways-can also shorten lifespan. Here we report a natural example of how the interplay between growth and lifespan can be epigenetically controlled. We find that a highly conserved RNA-modifying enzyme, the pseudouridine synthase Pus4/TruB, can act as a prion, endowing yeast with greater proliferation rates at the cost of a shortened lifespan. Cells harboring the prion grow larger and exhibit altered protein synthesis. This epigenetic state, [BIG+] (better in growth), allows cells to heritably yet reversibly alter their translational program, leading to the differential synthesis of dozens of proteins, including many that regulate proliferation and aging. Our data reveal a new role for prion-based control of an RNA-modifying enzyme in driving heritable epigenetic states that transform cell growth and survival.
View details for DOI 10.7554/eLife.60917
View details for PubMedID 34545808
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What Has a Century of Quantitative Genetics Taught Us About Nature's Genetic Toolkit?
Annual review of genetics
2020
Abstract
The complexity of heredity has been appreciated for decades: Many traits are controlled not by a single genetic locus but instead by polymorphisms throughout the genome. The importance of complex traits in biology and medicine has motivated diverse approaches to understanding their detailed genetic bases. Here, we focus on recent systematic studies, many in budding yeast, which have revealed that large numbers of all kinds of molecular variation, from noncoding to synonymous variants, can make significant contributions to phenotype. Variants can affect different traits in opposing directions, and their contributions can be modified by both the environment and the epigenetic state of the cell. The integration of prospective (synthesizing and analyzing variants) and retrospective (examining standing variation) approaches promises to reveal how natural selection shapes quantitative traits. Only by comprehensively understanding nature's genetic tool kit can we predict how phenotypes arise from the complex ensembles of genetic variants in living organisms. Expected final online publication date for the Annual Review of Genetics, Volume 54 is November 23, 2020. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
View details for DOI 10.1146/annurev-genet-021920-102037
View details for PubMedID 32897739
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Widespread Prion-Based Control of Growth and Differentiation Strategies in Saccharomyces cerevisiae.
Molecular cell
2019
Abstract
Theory and experiments suggest that organisms would benefit from pre-adaptation to future stressors based on reproducible environmental fluctuations experienced by their ancestors, but the mechanisms driving pre-adaptation remain enigmatic. We report that the [SMAUG+] prion allows yeast to anticipate nutrient repletion after periods of starvation, providing a strong selective advantage. By transforming the landscape of post-transcriptional gene expression, [SMAUG+] regulates the decision between two broad growth and survival strategies: mitotic proliferation or meiotic differentiation into a stress-resistant state. [SMAUG+] is common in laboratory yeast strains, where standard propagation practice produces regular cycles of nutrient scarcity followed by repletion. Distinct [SMAUG+] variants are also widespread in wild yeast isolates from multiple niches, establishing that prion polymorphs can be utilized in natural populations. Our data provide a striking example of how protein-based epigenetic switches, hidden in plain sight, can establish a transgenerational memory that integrates adaptive prediction into developmental decisions.
View details for DOI 10.1016/j.molcel.2019.10.027
View details for PubMedID 31757756
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Molecular Origins of Complex Heritability in Natural Genotype-to-Phenotype Relationships
CELL SYSTEMS
2019; 8 (5): 363-+
View details for DOI 10.1016/j.cels.2019.04.002
View details for Web of Science ID 000468628000003
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Molecular Origins of Complex Heritability in Natural Genotype-to-Phenotype Relationships.
Cell systems
2019
Abstract
The statistical complexity of heredity has long been evident, but its molecular origins remain elusive. Toinvestigate, we charted 90 comprehensive genotype-to-phenotype maps in a large population of wild diploid yeast. In contrast to long-standing assumptions, all types of genetic variation contributed similarly to phenotype. Causal synonymous and regulatory variants exhibited distinct molecular signatures, as did nonlinearities in heterozygote fitness that likely contribute to hybrid vigor. Highly pleiotropic variants altered disordered sequences within signaling hubs, and their effects correlated across environments-even when antagonistic-suggesting that large fitness gains bring concomitant costs. Naturalgenetic networks defined by the causal loci differed from those determined by precise gene deletionsor protein-protein interactions. Finally, we found that traits that would appear omnigenic in less powered studies do in fact have finite genetic determinants.Integrating these molecular principles will be crucial as genome reading and writing become routine in research, industry, and medicine.
View details for PubMedID 31054809
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Pervasive function and evidence for selection across standing genetic variation in S. cerevisiae.
Nature communications
2019; 10 (1): 1222
Abstract
Quantitative genetics aims to map genotype to phenotype, often with the goal of understanding how organisms evolved. However, it remains unclear whether the genetic variants identified are exemplary of evolution. Here we analyzed progeny of two wild Saccharomyces cerevisiae isolates to identify 195 loci underlying complex metabolic traits, resolving 107 to single polymorphisms with diverse molecular mechanisms. More than 20% of causal variants exhibited patterns of emergence inconsistent with neutrality. Moreover, contrary to drift-centric expectation, variation in diverse wild yeast isolates broadly exhibited this property: over 30% of shared natural variants exhibited phylogenetic signatures suggesting that they are not neutral. This pattern is likely attributable to both homoplasy and balancing selection on ancestral polymorphism. Variants that emerged repeatedly were more likely to have done so in isolates from the same ecological niche. Our results underscore the power of super-resolution mapping of ecologically relevant traits in understanding adaptation and evolution.
View details for PubMedID 30874558
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An estimate is worth about a thousand experiments: using order-of-magnitude estimates to identify cellular engineering targets
MICROBIAL CELL FACTORIES
2018; 17: 135
Abstract
Biotechnological processes use microbes to convert abundant molecules, such as glucose, into high-value products, such as pharmaceuticals, commodity and fine chemicals, and energy. However, from the outset of the development of a new bioprocess, it is difficult to determine the feasibility, expected yields, and targets for engineering. In this review, we describe a methodology that uses rough estimates to assess the feasibility of a process, approximate the expected product titer of a biological system, and identify variables to manipulate in order to achieve the desired performance. This methodology uses estimates from literature and biological intuition, and can be applied in the early stages of a project to help plan future engineering. We highlight recent literature examples, as well as two case studies from our own work, to demonstrate the use and power of rough estimates. Describing and predicting biological function using estimates guides the research and development phase of new bioprocesses and is a useful first step to understand and build a new microbial factory.
View details for PubMedID 30165868
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Spatially organizing biochemistry: choosing a strategy to translate synthetic biology to the factory
SCIENTIFIC REPORTS
2018; 8: 8196
Abstract
Natural biochemical systems are ubiquitously organized both in space and time. Engineering the spatial organization of biochemistry has emerged as a key theme of synthetic biology, with numerous technologies promising improved biosynthetic pathway performance. One strategy, however, may produce disparate results for different biosynthetic pathways. We use a spatially resolved kinetic model to explore this fundamental design choice in systems and synthetic biology. We predict that two example biosynthetic pathways have distinct optimal organization strategies that vary based on pathway-dependent and cell-extrinsic factors. Moreover, we demonstrate that the optimal design varies as a function of kinetic and biophysical properties, as well as culture conditions. Our results suggest that organizing biosynthesis has the potential to substantially improve performance, but that choosing the appropriate strategy is key. The flexible design-space analysis we propose can be adapted to diverse biosynthetic pathways, and lays a foundation to rationally choose organization strategies for biosynthesis.
View details for PubMedID 29844460
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Quantitative characterization of all single amino acid variants of a viral capsid-based drug delivery vehicle
NATURE COMMUNICATIONS
2018; 9: 1385
Abstract
Self-assembling proteins are critical to biological systems and industrial technologies, but predicting how mutations affect self-assembly remains a significant challenge. Here, we report a technique, termed SyMAPS (Systematic Mutation and Assembled Particle Selection), that can be used to characterize the assembly competency of all single amino acid variants of a self-assembling viral structural protein. SyMAPS studies on the MS2 bacteriophage coat protein revealed a high-resolution fitness landscape that challenges some conventional assumptions of protein engineering. An additional round of selection identified a previously unknown variant (CP[T71H]) that is stable at neutral pH but less tolerant to acidic conditions than the wild-type coat protein. The capsids formed by this variant could be more amenable to disassembly in late endosomes or early lysosomes-a feature that is advantageous for delivery applications. In addition to providing a mutability blueprint for virus-like particles, SyMAPS can be readily applied to other self-assembling proteins.
View details for PubMedID 29643335
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Organizing biochemistry in space and time using prion-like self-assembly.
Current opinion in systems biology
2018; 8: 16–24
Abstract
Prion-like proteins have the capacity to adopt multiple stable conformations, at least one of which can recruit proteins from the native conformation into the alternative fold. Although classically associated with disease, prion-like assembly has recently been proposed to organize a range of normal biochemical processes in space and time. Organisms from bacteria to mammals use prion-like mechanisms to (re)organize their proteome in response to intracellular and extracellular stimuli. Prion-like behavior is an economical means to control biochemistry and gene regulation at the systems level, and prions can act as protein-based genes to facilitate quasi-Lamarckian inheritance of induced traits. These mechanisms allow individual cells to express distinct heritable traits using the same complement of polypeptides. Understanding and controlling prion-like behavior is therefore a promising strategy to combat diverse pathologies and organize engineered biological systems.
View details for PubMedID 29725624
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Evidence for Improved Encapsulated Pathway Behavior in a Bacterial Microcompartment through Shell Protein Engineering
ACS SYNTHETIC BIOLOGY
2017; 6 (10): 1880–91
Abstract
Bacterial microcompartments are a class of proteinaceous organelles comprising a characteristic protein shell enclosing a set of enzymes. Compartmentalization can prevent escape of volatile or toxic intermediates, prevent off-pathway reactions, and create private cofactor pools. Encapsulation in synthetic microcompartment organelles will enhance the function of heterologous pathways, but to do so, it is critical to understand how to control diffusion in and out of the microcompartment organelle. To this end, we explored how small differences in the shell protein structure result in changes in the diffusion of metabolites through the shell. We found that the ethanolamine utilization (Eut) protein EutM properly incorporates into the 1,2-propanediol utilization (Pdu) microcompartment, altering native metabolite accumulation and the resulting growth on 1,2-propanediol as the sole carbon source. Further, we identified a single pore-lining residue mutation that confers the same phenotype as substitution of the full EutM protein, indicating that small molecule diffusion through the shell is the cause of growth enhancement. Finally, we show that the hydropathy index and charge of pore amino acids are important indicators to predict how pore mutations will affect growth on 1,2-propanediol, likely by controlling diffusion of one or more metabolites. This study highlights the use of two strategies to engineer microcompartments to control metabolite transport: altering the existing shell protein pore via mutation of the pore-lining residues, and generating chimeras using shell proteins with the desired pores.
View details for PubMedID 28585808
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De novo design of signal sequences to localize cargo to the 1,2-propanediol utilization microcompartment
PROTEIN SCIENCE
2017; 26 (5): 1086-1092
Abstract
Organizing heterologous biosyntheses inside bacterial cells can alleviate common problems owing to toxicity, poor kinetic performance, and cofactor imbalances. A subcellular organelle known as a bacterial microcompartment, such as the 1,2-propanediol utilization microcompartment of Salmonella, is a promising chassis for this strategy. Here we demonstrate de novo design of the N-terminal signal sequences used to direct cargo to these microcompartment organelles. We expand the native repertoire of signal sequences using rational and library-based approaches and show that a canonical leucine-zipper motif can function as a signal sequence for microcompartment localization. Our strategy can be applied to generate new signal sequences localizing arbitrary cargo proteins to the 1,2-propanediol utilization microcompartments.
View details for DOI 10.1002/pro.3144
View details for Web of Science ID 000400166800016
View details for PubMedCentralID PMC5405430