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Orr AA, Yang J, Sule N, Chawla R, Hull KG, Zhu M, Romo D, Lele PP, Jayaraman A, Manson MD, Tamamis P. Molecular Mechanism for Attractant Signaling to DHMA by E. coli Tsr. Biophys J 2019; 118:492-504. [PMID: 31839263 DOI: 10.1016/j.bpj.2019.11.3382] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 11/05/2019] [Accepted: 11/19/2019] [Indexed: 12/20/2022] Open
Abstract
The attractant chemotaxis response of Escherichia coli to norepinephrine requires that it be converted to 3,4-dihydroxymandelic acid (DHMA) by the monoamine oxidase TynA and the aromatic aldehyde dehydrogenase FeaB. DHMA is sensed by the serine chemoreceptor Tsr, and the attractant response requires that at least one subunit of the periplasmic domain of the Tsr homodimer (pTsr) has an intact serine-binding site. DHMA that is generated in vivo by E. coli is expected to be a racemic mixture of the (R) and (S) enantiomers, so it has been unclear whether one or both chiral forms are active. Here, we used a combination of state-of-the-art tools in molecular docking and simulations, including an in-house simulation-based docking protocol, to investigate the binding properties of (R)-DHMA and (S)-DHMA to E. coli pTsr. Our studies computationally predicted that (R)-DHMA should promote a stronger attractant response than (S)-DHMA because of a consistently greater-magnitude piston-like pushdown of the pTsr α-helix 4 toward the membrane upon binding of (R)-DHMA than upon binding of (S)-DHMA. This displacement is caused primarily by interaction of DHMA with Tsr residue Thr156, which has been shown by genetic studies to be critical for the attractant response to L-serine and DHMA. These findings led us to separate the two chiral species and test their effectiveness as chemoattractants. Both the tethered cell and motility migration coefficient assays validated the prediction that (R)-DHMA is a stronger attractant than (S)-DHMA. Our study demonstrates that refined computational docking and simulation studies combined with experiments can be used to investigate situations in which subtle differences between ligands may lead to diverse chemotactic responses.
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Affiliation(s)
- Asuka A Orr
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas
| | - Jingyun Yang
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas
| | - Nitesh Sule
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas
| | - Ravi Chawla
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas
| | - Kenneth G Hull
- Department of Chemistry & Biochemistry and CPRIT Synthesis and Drug-Lead Discovery Laboratory, Baylor University, Waco, Texas
| | - Mingzhao Zhu
- Department of Chemistry & Biochemistry and CPRIT Synthesis and Drug-Lead Discovery Laboratory, Baylor University, Waco, Texas
| | - Daniel Romo
- Department of Chemistry & Biochemistry and CPRIT Synthesis and Drug-Lead Discovery Laboratory, Baylor University, Waco, Texas
| | - Pushkar P Lele
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas
| | - Arul Jayaraman
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas
| | - Michael D Manson
- Department of Biology, Texas A&M University, College Station, Texas.
| | - Phanourios Tamamis
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas.
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Schmidt C, Macpherson JA, Lau AM, Tan KW, Fraternali F, Politis A. Surface Accessibility and Dynamics of Macromolecular Assemblies Probed by Covalent Labeling Mass Spectrometry and Integrative Modeling. Anal Chem 2017; 89:1459-1468. [PMID: 28208298 PMCID: PMC5299547 DOI: 10.1021/acs.analchem.6b02875] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 01/04/2017] [Indexed: 12/22/2022]
Abstract
Mass spectrometry (MS) has become an indispensable tool for investigating the architectures and dynamics of macromolecular assemblies. Here we show that covalent labeling of solvent accessible residues followed by their MS-based identification yields modeling restraints that allow mapping the location and orientation of subunits within protein assemblies. Together with complementary restraints derived from cross-linking and native MS, we built native-like models of four heterocomplexes with known subunit structures and compared them with available X-ray crystal structures. The results demonstrated that covalent labeling followed by MS markedly increased the predictive power of the integrative modeling strategy enabling more accurate protein assembly models. We applied this strategy to the F-type ATP synthase from spinach chloroplasts (cATPase) providing a structural basis for its function as a nanomotor. By subjecting the models generated by our restraint-based strategy to molecular dynamics (MD) simulations, we revealed the conformational states of the peripheral stalk and assigned flexible regions in the enzyme. Our strategy can readily incorporate complementary chemical labeling strategies and we anticipate that it will be applicable to many other systems providing new insights into the structure and function of protein complexes.
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Affiliation(s)
- Carla Schmidt
- Interdisciplinary
Research Center HALOmem, Martin Luther University
Halle-Wittenberg, Kurt-Mothes-Strasse 3, 06120 Halle/Saale, Germany
| | - Jamie A. Macpherson
- Division
of Cell & Molecular Biophysics, King’s
College London, New Hunt’s
House, SE1 1UL, London, United Kingdom
| | - Andy M. Lau
- Department
of Chemistry, King’s College London, 7 Trinity Street, SE1 1DB, London, United Kingdom
| | - Ken Wei Tan
- Department
of Chemistry, King’s College London, 7 Trinity Street, SE1 1DB, London, United Kingdom
| | - Franca Fraternali
- Division
of Cell & Molecular Biophysics, King’s
College London, New Hunt’s
House, SE1 1UL, London, United Kingdom
| | - Argyris Politis
- Department
of Chemistry, King’s College London, 7 Trinity Street, SE1 1DB, London, United Kingdom
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