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Roussel G, Lindner E, White SH. Stabilization of SecA ATPase by the primary cytoplasmic salt of Escherichia coli. Protein Sci 2019; 28:984-989. [PMID: 30968480 DOI: 10.1002/pro.3619] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 04/08/2019] [Indexed: 11/11/2022]
Abstract
Much is known about the structure, function, and stability of the SecA motor ATPase that powers the secretion of periplasmic proteins across the inner membrane of Escherichia coli. Most studies of SecA are carried out in buffered sodium or potassium chloride salt solutions. However, the principal intracellular salt of E. coli is potassium glutamate (KGlu), which is known to stabilize folded proteins and protein-nucleic acid complexes. Here we report that KGlu stabilizes SecA, including its dimeric state, and increases its ATPase activity, suggesting that SecA is likely fully folded, stable, and active in vivo at 37°C. Furthermore, KGlu also stabilizes a precursor form of the secreted maltose-binding protein.
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Affiliation(s)
- Guillaume Roussel
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California, 92697-4560
| | - Eric Lindner
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California, 92697-4560
| | - Stephen H White
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California, 92697-4560
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2
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Chada N, Chattrakun K, Marsh BP, Mao C, Bariya P, King GM. Single-molecule observation of nucleotide induced conformational changes in basal SecA-ATP hydrolysis. SCIENCE ADVANCES 2018; 4:eaat8797. [PMID: 30397644 PMCID: PMC6200364 DOI: 10.1126/sciadv.aat8797] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 09/13/2018] [Indexed: 05/06/2023]
Abstract
SecA is the critical adenosine triphosphatase that drives preprotein transport through the translocon, SecYEG, in Escherichia coli. This process is thought to be regulated by conformational changes of specific domains of SecA, but real-time, real-space measurement of these changes is lacking. We use single-molecule atomic force microscopy (AFM) to visualize nucleotide-dependent conformations and conformational dynamics of SecA. Distinct topographical populations were observed in the presence of specific nucleotides. AFM investigations during basal adenosine triphosphate (ATP) hydrolysis revealed rapid, reversible transitions between a compact and an extended state at the ~100-ms time scale. A SecA mutant lacking the precursor-binding domain (PBD) aided interpretation. Further, the biochemical activity of SecA prepared for AFM was confirmed by tracking inorganic phosphate release. We conclude that ATP-driven dynamics are largely due to PBD motion but that other segments of SecA contribute to this motion during the transition state of the ATP hydrolysis cycle.
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Affiliation(s)
- Nagaraju Chada
- Department of Physics and Astronomy, University of Missouri–Columbia, Columbia, MO 65211, USA
| | - Kanokporn Chattrakun
- Department of Physics and Astronomy, University of Missouri–Columbia, Columbia, MO 65211, USA
| | - Brendan P. Marsh
- Department of Physics and Astronomy, University of Missouri–Columbia, Columbia, MO 65211, USA
| | - Chunfeng Mao
- Department of Biochemistry, University of Missouri–Columbia, Columbia, MO 65211, USA
| | - Priya Bariya
- Department of Biochemistry, University of Missouri–Columbia, Columbia, MO 65211, USA
| | - Gavin M. King
- Department of Physics and Astronomy, University of Missouri–Columbia, Columbia, MO 65211, USA
- Department of Biochemistry, University of Missouri–Columbia, Columbia, MO 65211, USA
- Corresponding author.
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3
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Motions of the SecA protein motor bound to signal peptide: Insights from molecular dynamics simulations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:416-427. [DOI: 10.1016/j.bbamem.2017.11.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Revised: 11/03/2017] [Accepted: 11/07/2017] [Indexed: 12/31/2022]
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4
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Wowor AJ, Yan Y, Auclair SM, Yu D, Zhang J, May ER, Gross ML, Kendall DA, Cole JL. Analysis of SecA dimerization in solution. Biochemistry 2014; 53:3248-60. [PMID: 24786965 PMCID: PMC4030788 DOI: 10.1021/bi500348p] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
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The Sec pathway mediates translocation
of protein across the inner
membrane of bacteria. SecA is a motor protein that drives translocation
of preprotein through the SecYEG channel. SecA reversibly dimerizes
under physiological conditions, but different dimer interfaces have
been observed in SecA crystal structures. Here, we have used biophysical
approaches to address the nature of the SecA dimer that exists in
solution. We have taken advantage of the extreme salt sensitivity
of SecA dimerization to compare the rates of hydrogen–deuterium
exchange of the monomer and dimer and have analyzed the effects of
single-alanine substitutions on dimerization affinity. Our results
support the antiparallel dimer arrangement observed in one of the
crystal structures of Bacillus subtilis SecA. Additional
residues lying within the preprotein binding domain and the C-terminus
are also protected from exchange upon dimerization, indicating linkage
to a conformational transition of the preprotein binding domain from
an open to a closed state. In agreement with this interpretation,
normal mode analysis demonstrates that the SecA dimer interface influences
the global dynamics of SecA such that dimerization stabilizes the
closed conformation.
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Affiliation(s)
- Andy J Wowor
- Department of Pharmaceutical Sciences, University of Connecticut , Storrs, Connecticut 06269, United States
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5
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Chatzi KE, Sardis MF, Economou A, Karamanou S. SecA-mediated targeting and translocation of secretory proteins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:1466-74. [PMID: 24583121 DOI: 10.1016/j.bbamcr.2014.02.014] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 02/12/2014] [Accepted: 02/15/2014] [Indexed: 11/26/2022]
Abstract
More than 30 years of research have revealed that the dynamic nanomotor SecA is a central player in bacterial protein secretion. SecA associates with the SecYEG channel and transports polypeptides post-translationally to the trans side of the cytoplasmic membrane. It comprises a helicase-like ATPase core coupled to two domains that provide specificity for preprotein translocation. Apart from SecYEG, SecA associates with multiple ligands like ribosomes, nucleotides, lipids, chaperones and preproteins. It exerts its essential contribution in two phases. First, SecA, alone or in concert with chaperones, helps mediate the targeting of the secretory proteins from the ribosome to the membrane. Next, at the membrane it converts chemical energy to mechanical work and translocates preproteins through the SecYEG channel. SecA is a highly dynamic enzyme, it exploits disorder-order kinetics, swiveling and dissociation of domains and dimer to monomer transformations that are tightly coupled with its catalytic function. Preprotein signal sequences and mature domains exploit these dynamics to manipulate the nanomotor and thus achieve their export at the expense of metabolic energy. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.
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Affiliation(s)
- Katerina E Chatzi
- Institute of Molecular Biology and Biotechnology, FORTH, University of Crete, PO Box 1385, GR-711 10 Iraklio, Crete, Greece; KU Leuven, Rega Institute for Medical Research, Department of Microbiology and Immunology, Laboratory of Molecular Bacteriology, 3000 Leuven, Belgium
| | - Marios Frantzeskos Sardis
- KU Leuven, Rega Institute for Medical Research, Department of Microbiology and Immunology, Laboratory of Molecular Bacteriology, 3000 Leuven, Belgium
| | - Anastassios Economou
- Institute of Molecular Biology and Biotechnology, FORTH, University of Crete, PO Box 1385, GR-711 10 Iraklio, Crete, Greece; Department of Biology, University of Crete, PO Box 1385, GR-711 10 Iraklio, Crete, Greece; KU Leuven, Rega Institute for Medical Research, Department of Microbiology and Immunology, Laboratory of Molecular Bacteriology, 3000 Leuven, Belgium.
| | - Spyridoula Karamanou
- Institute of Molecular Biology and Biotechnology, FORTH, University of Crete, PO Box 1385, GR-711 10 Iraklio, Crete, Greece; KU Leuven, Rega Institute for Medical Research, Department of Microbiology and Immunology, Laboratory of Molecular Bacteriology, 3000 Leuven, Belgium.
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6
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Rao C V S, De Waelheyns E, Economou A, Anné J. Antibiotic targeting of the bacterial secretory pathway. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:1762-83. [PMID: 24534745 DOI: 10.1016/j.bbamcr.2014.02.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 01/27/2014] [Accepted: 02/06/2014] [Indexed: 02/06/2023]
Abstract
Finding new, effective antibiotics is a challenging research area driven by novel approaches required to tackle unconventional targets. In this review we focus on the bacterial protein secretion pathway as a target for eliminating or disarming pathogens. We discuss the latest developments in targeting the Sec-pathway for novel antibiotics focusing on two key components: SecA, the ATP-driven motor protein responsible for driving preproteins across the cytoplasmic membrane and the Type I signal peptidase that is responsible for the removal of the signal peptide allowing the release of the mature protein from the membrane. We take a bird's-eye view of other potential targets in the Sec-pathway as well as other Sec-dependent or Sec-independent protein secretion pathways as targets for the development of novel antibiotics. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.
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Affiliation(s)
- Smitha Rao C V
- Laboratory of Molecular Bacteriology, Rega Institute, Department of Microbiology and Immunology, KU Leuven, O&N1, 6th floor, Herestraat 49, P.O. Box 1037, B-3000 Leuven, Belgium.
| | - Evelien De Waelheyns
- Laboratory of Molecular Bacteriology, Rega Institute, Department of Microbiology and Immunology, KU Leuven, O&N1, 6th floor, Herestraat 49, P.O. Box 1037, B-3000 Leuven, Belgium.
| | - Anastassios Economou
- Laboratory of Molecular Bacteriology, Rega Institute, Department of Microbiology and Immunology, KU Leuven, O&N1, 6th floor, Herestraat 49, P.O. Box 1037, B-3000 Leuven, Belgium; Institute of Molecular Biology and Biotechnology, FORTH, University of Crete, P.O. Box 1385, GR-711 10 Iraklio, Crete, Greece; Department of Biology, University of Crete, P.O. Box 1385, GR-71110 Iraklio, Crete, Greece.
| | - Jozef Anné
- Laboratory of Molecular Bacteriology, Rega Institute, Department of Microbiology and Immunology, KU Leuven, O&N1, 6th floor, Herestraat 49, P.O. Box 1037, B-3000 Leuven, Belgium.
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Stoichiometry of SecYEG in the active translocase of Escherichia coli varies with precursor species. Proc Natl Acad Sci U S A 2013; 110:11815-20. [PMID: 23818593 DOI: 10.1073/pnas.1303289110] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have established a reconstitution system for the translocon SecYEG in proteoliposomes in which 55% of the accessible translocons are active. This level corresponds to the fraction of translocons that are active in vitro when assessed in their native environment of cytoplasmic membrane vesicles. Assays using these robust reconstituted proteoliposomes and cytoplasmic membrane vesicles have revealed that the number of SecYEG units involved in an active translocase depends on the precursor undergoing transfer. The active translocase for the precursor of periplasmic galactose-binding protein contains twice the number of heterotrimeric units of SecYEG as does that for the precursor of outer membrane protein A.
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The how’s and why’s of protein folding intermediates. Arch Biochem Biophys 2013; 531:14-23. [DOI: 10.1016/j.abb.2012.10.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 10/05/2012] [Accepted: 10/11/2012] [Indexed: 12/13/2022]
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