Office: 203A Stephens Hall
117 Schweitzer Hall
University of Missouri
Columbia, MO 65211
|BS||Colorado State University||Fort Collins, Colo.||Zoology|
|PhD||University of Wisconsin||Madison, Wis.||Molecular Biology|
We aim to elucidate the mechanism of protein export in Escherichia coli with emphasis on the interactions of the protein components of the pathway. Translocation of specific, newly synthesized polypeptides across biological membranes is a ubiquitous process that is essential for living cells. Whether the process occurs in eukaryotes or in prokaryotes in almost all cases molecular chaperones are involved. Chaperones are a family of proteins that display the remarkable ability to recognize and bind polypeptides based on the fact that the ligands are in a nonnative state.
Our research is focused on the molecular chaperone SecB and its promiscuous interactions with polypeptide ligands as well as its specific interactions with the protein SecA, which is an ATPase that serves as the motor for transfer of proteins across the membrane. We study the interactions among the proteins using a wide range of techniques. These include the following biophysical techniques: column chromatography, dynamic light scattering, calorimetry, fluorescence spectroscopy, analytical centrifugation, mass spectrometry, and electron paramagnetic spin resonance. We also have established an in vitro protein translocation system and assays of the ATPase activity of SecA.
Mao C, Cheadle CE, Hardy SJ, Lilly AA, Suo Y, Sanganna Gari RR, King GM, Randall LL. Stoichiometry of SecYEG in the active translocase of Escherichia coli varies with precursor species. Proc Natl Acad Sci U S A. 2013 Jul 16;110(29):11815-20.
Sanganna Gari RR, Frey NC, Mao C, Randall LL, King GM. Dynamic structure of the translocon SecYEG in membrane: direct single molecule observations. J Biol Chem. 2013 Jun 7;288(23):16848-54.
Suo Y, Hardy SJ, Randall LL. Orientation of SecA and SecB in complex, derived from disulfide cross-linking. J Bacteriol. 2011 Jan;193(1):190-6. doi: 10.1128/JB.00975-10. Epub 2010 Oct 29.
Randall LL, Henzl MT. Direct identification of the site of binding on the chaperone SecB for the amino terminus of the translocon motor SecA. Protein Sci. 2010 Jun;19(6):1173-9. doi: 10.1002/pro.392.
Lilly A.A., Crane J.M., Randall L.L. Export chaperone SecB uses one surface of interaction for diverse unfolded polypeptide ligands. Protein Sci. 18: 1860-1868 (2009).
Mao C., Hardy S.J., Randall L.L. Maximal efficiency of coupling between ATP hydrolysis and translocation of polypeptides mediated by SecB requires two protomers of SecA. J. Bacteriol. 191: 978-84 (2009).
Cooper D.B., Smith V.F., Crane J.M., Roth H.C., Lilly A.A., Randall L.L. SecA, the motor of the secretion machine, binds diverse partners on one interactive surface. J. Mol. Biol. 382: 74-87 (2008).
Crane, J. M., Suo, Y., Lilly, A. A., Mao, C. Hubbell, W. L., and Randall, L. L. 2006. Sites of interaction of a precursor polypeptide on the export chaperone SecB mapped by site-directed spin labeling. J. Mol. Biol. 363: 63-74.