Contact Information:

Dept. of Microbiology and
Molecular Genetics

Harvard Medical School

200 Longwood Ave.

Boston, MA 02115

phone: 617-432-1920

fax: 617-738-7664

jbeckwith@hms.harvard.edu

Beckwith Lab Home

Research Summary

We use the bacterium Escherichia coli to study the following fundamental problems of cell biology.

Protein secretion: We study the specific features of signal sequences that determine which pathways their cognate proteins follow for protein secretion. We also characterize the cellular components required for the somewhat analogous process of incorporation of proteins into the cytoplasmic membrane.

Membrane protein structure: We have developed a gene fusion technique for determining the topology of integral membrane proteins within the lipid bilayer. A second genetic technique allows us to define interactions between membrane-imbedded segments of such proteins. From these approaches, we can learn more about the secondary and tertiary structure of membrane proteins and develop predictive algorithms for defining interactions between membrane proteins.

Protein folding: We are characterizing a set of enzymes that are required for the efficient formation and isomerization of disulfide bonds in proteins of the bacterial cell envelope. These enzymes are members of a large family of 11 or more proteins in E. coli known as the thioredoxin superfamily. We are studying the mechanism of action of these proteins, the mechanisms by which they receive or donate electrons necessary for their function, and the specific role of each protein in the physiology of the cell. These studies not only yield interesting basic science findings, but also have proved useful in engineering E. coli to be an efficient system for expressing foreign proteins with multiple disulfide bonds.

Cell division: We are studying the role played by cytoplasmic membrane proteins in the process of cell division using techniques of gene fusion, domain swapping and fluorescence microscopy. We wish to understand how the formation of a complex structure such as occurs during cell division is initiated and propagated.

Selected Publications

Dutton, R.J., Wayman, A., Wei, J.-R., Rubin, E.J., Beckwith, J., and Boyd, D. Inhibition of bacterial disulfide bond formation by the anti-coagulant warfarin. Proc. Natl. Acad. Sci.(in press).

Kadokura, H., and Beckwith, J. Detecting folding intermediates of a protein as it passes through the bacterial translocon. Cell 138:1164-1173 (2009).

Dutton, R.J., Boyd, D., Berkmen. M., and Beckwith, J. Bacterial species exhibit diversity in their mechanisms and capacity for protein disulfide bond formation. Proc. Natl. Acad. Sci., U.S.A. 105:11933-11938 (2008).

Faulkner, M.J., Veeravalli, K., Gon, S., Georgiou, G., and Beckwith, J. Functional plasticity of a peroxidase allows evolution of diverse disulfide-reducing pathways. Proc. Natl. Acad. Sci. U.S.A.105:6735-40 (2008).

Beckwith, J. What Lies Beyond Uranus? Preconceptions, Ignorance, Serendipity and Suppressors in the Search for Biology's Secrets. Genetics 176:733-740 (2007).

Cho, S.-H., Porat, A., Ye, J., and Beckwith, J. Redox-active cysteines of a membrane electron transporter DsbD show dual compartment accessibility.  EMBO J. 8:3509-3520 (2007).