Single molecule studies of the protein export system

ORAL

Abstract

Numerous proteins are exported across or into cell membranes to carry out critical cellular functions. In \textit{Escherichia coli,} pathway through the membrane is provided by the translocon SecYEG, which is highly conserved and has homologs across the kingdoms of life. At the cytoplasmic membrane SecA binds SecYEG and provides energy for protein translocation through the cycle of binding and hydrolysis of ATP. SecA makes large surface area contact ($\sim$ 6,800 {\AA}$^{2})$ with cytoplasmic loops spanning TM helices 6-7 and 8-9 of SecY. Despite their functional significance, measurements of these flexible and disordered protein regions remain a significant experimental challenge. Major challenges in protein export system include: determining the oligomeric state of SecYEG and SecA during protein export, and elucidating the mechanism of SecA driving precursor through translocon. Structural details at single molecule level in near native conditions can address these major questions. Recently, atomic force microscopy (AFM) has emerged as an important complementary tool to study membrane proteins. In contrast to other techniques AFM can directly monitor conformational changes and dynamics of bio-molecules. In this work we present the structural details of major components of protein export system at single molecule level in native conditions determined via AFM.

Authors

  • Raghavendar Reddy Sanganna Gari

    University of Missouri-Columbia

  • Nathan Frey

    University of Missouri-Columbia

  • Mark Neubauer

    University of Missouri-Columbia, Southern Illinois University Carbondale, Indiana University, Purdue University, Argonne National Laboratory, University of Missouri, College of Physics Science, Qingda University, Qingdao, 266071, China, Indian Institute of Science, Bangalore, India, University of Massachusetts Amherst, Iowa State University, Technical University of Denmark, University of Missouri - Columbia, University of California - San Diego, La Jolla, CA 92093, Department of Physics, University of Missouri-Columbia, Columbia, Missouri 65211, Department of Physics and Astronomy, University of Missouri-Columbia, University of Missouri, Columbia, MO, Department of Physics and Department of Biochemistry, University of Missouri, Columbia, MO 65211, Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599-3290, Univ of Missouri - Columbia, Duke University, Shanghai Jiaotong University, Ames Laboratory, U.S. DOE, Texas Center of Superconductivity and the Department of Physics, University of Houston, Institute of Physics, Siberian Division, Russian Academy of Sciences, Krasnoyarsk, 66036, Russia, Oak Ridge National Laboratory, NIST Center for Neutron Research, MU Research Reactor, Ames Laboratory and Dep. of Physics and Astronomy, Iowa State University, AmesAmes Laboratory and Dep. of Physics and Astronomy, Iowa State University, HFIR, Oak Ridge National Laboratory, University of Illinois at Urbana-Champaign

  • G.M. King

    University of Missouri-Columbia, University of Missouri - Columbia