Ph.D., Harvard University, Biophysics (2012)
S.M., Harvard University, Applied Mathematics (2008)
A.B., Harvard University, Chemistry and Physics (2006)
Michael Bassik, Postdoctoral Faculty Sponsor
Orthogonal Labeling of M13 Minor Capsid Proteins with DNA to Self-Assemble End-to-End Multiphage Structures
ACS SYNTHETIC BIOLOGY
2013; 2 (9): 490-496
M13 bacteriophage has been used as a scaffold to organize materials for various applications. Building more complex multiphage devices requires precise control of interactions between the M13 capsid proteins. Toward this end, we engineered a loop structure onto the pIII capsid protein of M13 bacteriophage to enable sortase-mediated labeling reactions for C-terminal display. Combining this with N-terminal sortase-mediated labeling, we thus created a phage scaffold that can be labeled orthogonally on three capsid proteins: the body and both ends. We show that covalent attachment of different DNA oligonucleotides at the ends of the new phage structure enables formation of multiphage particles oriented in a specific order. These have potential as nanoscale scaffolds for multi-material devices.
View details for DOI 10.1021/sb4000195
View details for Web of Science ID 000324842100002
View details for PubMedID 23713956
M13 Bacteriophage Display Framework That Allows Sortase-Mediated Modification of Surface-Accessible Phage Proteins
2012; 23 (7): 1478-1487
We exploit bacterial sortases to attach a variety of moieties to the capsid proteins of M13 bacteriophage. We show that pIII, pIX, and pVIII can be functionalized with entities ranging from small molecules (e.g., fluorophores, biotin) to correctly folded proteins (e.g., GFP, antibodies, streptavidin) in a site-specific manner, and with yields that surpass those of any reported using phage display technology. A case in point is modification of pVIII. While a phage vector limits the size of the insert into pVIII to a few amino acids, a phagemid system limits the number of copies actually displayed at the surface of M13. Using sortase-based reactions, a 100-fold increase in the efficiency of display of GFP onto pVIII is achieved. Taking advantage of orthogonal sortases, we can simultaneously target two distinct capsid proteins in the same phage particle and maintain excellent specificity of labeling. As demonstrated in this work, this is a simple and effective method for creating a variety of structures, thus expanding the use of M13 for materials science applications and as a biological tool.
View details for DOI 10.1021/bc300130z
View details for Web of Science ID 000306452500015
View details for PubMedID 22759232
Cellular binding, motion, and internalization of synthetic gene delivery polymers
BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH
2007; 1773 (10): 1583-1588
Using fluorescence microscopy we have tracked the cellular binding, surface motion, and internalization of polyarginine and polyethylenimine, cationic ligands used for gene and protein delivery. Each ligand was complexed with a quantum dot to provide a photostable probe. Transfection with exogenous DNA was used to relate the observed motion to gene delivery. Cell surface motion was independent of sulfated proteoglycans, but dependent on cholesterol. Cellular internalization required sulfated proteoglycans and cholesterol. These observations suggest that sulfated proteoglycans act as cellular receptors for the cationic ligands, rather than only passive binding sites. Understanding the interaction of polyarginine and polyethylenimine with the plasma membrane may assist in designing more efficient gene delivery systems.
View details for DOI 10.1016/j.bbamcr.2007.07.009
View details for Web of Science ID 000250528400009
View details for PubMedID 17888530