Joshua W. Shaevitz

shaevitz	Shaevitz Research Lab
(609) 258-8177	Carl Icahn Lab, 150
	Lab (609) 258-5959
Faculty Assistant	Deborah Koehler
This email address is being protected from spambots. You need JavaScript enabled to view it.	(609) 258-0436

Research Focus

Cellular and molecular biophysics; Shape, mechanics and motility

The cells that make up all living organisms come in a dizzying array of sizes and shapes, each with unique structural and mechanical properties. When many cells move they contort their bodies to glide along surfaces or swim through fluid. We are interested in the different physical strategies that mother nature has found to create the cellular and sub-cellular structures that perform these amazing feats.

One of the species we study, Spiroplasma melliferum, is a helix barely more than 100 nm across and a few microns long. How does this cell achieve its beautiful shape? When these cells swim they change the helicity of their entire bodies to produce movement. How does this work? How can a cell organize its contents in such a tightly packed space?

It was recently discovered that many, if not all, bacteria use an internal cytoskelton to define their shape, to guide intracellular organization and to produce movement. Our lab studies physical aspects of the prokaryotic cytoskeleton. What are the structural properties of the individual cytoskeletal filaments and how do they contribute to overall cell mechanics? Is mechanical stress induced by the cytoskeleton used to determine cell shape? Are these filaments used as tracks by molecular motors as they are in eukaryotes by kinesin and myosin? These are just some of the basic questions that our lab is interested in.

For this research, we are developing new instrumentation that combines mechanical perturbation of cells and molecules with visualization of key protein and macromolecular structures. Our toolbox includes unique combinations of optical microscopy, fluorescence and deconvolution microscopy, optical trapping, atomic force microscopy, as well as biophysical modeling and simulation.

Selected Publications

Wang S, Shaevitz JW. (2013) The mechanics of shape in prokaryotes. Front Biosci (Schol Ed). 5: 564-74. Pubmed

Pilizota T, Shaevitz JW. (2012) Fast, multiphase volume adaptation to hyperosmotic shock by Escherichia coli. PLoS One. 7: e35205. PubMed

van Teeffelen S, Shaevitz JW, Gitai Z. (2012) Image analysis in fluorescence microscopy: bacterial dynamics as a case study. Bioessays. 34: 427-436. PubMed

Wang S, Furchtgott L, Huang KC, Shaevitz JW. (2012) Helical insertion of peptidoglycan produces chiral ordering of the bacterial cell wall. Proc Natl Acad Sci. 109: E595-604. PubMed

Sun M, Wartel M, Cascales E, Shaevitz JW, Mignot T. (2011) Motor-driven intracellular transport powers bacterial gliding motility. Proc Natl Acad Sci. 108: 7559-7564. PubMed

Shaevitz JW, Gitai Z. (2010) The structure and function of bacterial actin homologs. Cold Spring Harb Perspect Biol. 2: a000364. PubMed

Wang S, Arellano-Santoyo H, Combs PA, Shaevitz JW. (2010) Actin-like cytoskeleton filaments contribute to cell mechanics in bacteria. Proc Natl Acad Sci 107: 9182-9185. PubMed

Wang S, Arellano-Santoyo H, Combs PA, Shaevitz JW. (2010) Measuring the bending stiffness of bacterial cells using an optical trap. J Vis Exp. pii: 2012. PubMed

Deng Y, Shaevitz JW. (2009) Effect of aberration on height calibration in three-dimensional localization-based microscopy and particle tracking. Appl Opt. 48: 1886-1890. PubMed

Shaevitz JW, Fletcher DA. (2008) Curvature and torsion in growing actin networks. Phys Biol. 5: 26006. PubMed

Shaevitz JW, Fletcher DA. (2007) Enhanced three-dimensional deconvolution microscopy using a measured depth-varying point spread function JOSA A. 24: 2622-2627.

Mignot T, Shaevitz JW, Hartzell PL, Zusman DR. (2007) Evidence that focal adhesion complexes power bacterial gliding motility. Science 315: 853-856. PubMed

Abbondanzieri EA, Greenleaf WJ, Shaevitz JW, Landick R, Block SM. (2005) Direct observation of base-pair stepping by RNA polymerase. Nature 438: 460-465. PubMed

Abbondanzieri EA, Shaevitz JW, Block SM. (2005) Picocalorimetry of transcription by RNA polymerase. Biophys J 89: L61-L63. PubMed

Shaevitz JW, Block SM, Schnitzer MJ. (2005) Statistical kinetics of macromolecular dynamics. Biophys J 89: 2277-2285. PubMed

Shaevitz JW, Lee JY, Fletcher DA. (2005) Spiroplasma swim by a processive change in body helicity. Cell 122: 941-945. PubMed

Shaevitz JW, Abbondanzieri EA, Landick R, Block SM. (2003) Backtracking by single RNA polymerase molecules observed at near-base-pair resolution. Nature 426: 684-687. PubMed

Block SM, Asbury CL, Shaevitz JW, Lang MJ. (2003) Probing the kinesin reaction cycle with a 2D optical force clamp. Proc Natl Acad Sci 100: 2351-2356. PubMed.

Lang MJ, Asbury CL, Shaevitz JW, Block SM. (2002) An automated two-dimensional optical force clamp for single molecule studies. Biophys J 83: 491-501. PubMed