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Jin J, Hsieh YH, Chaudhary AS, Cui J, Houghton JE, Sui SF, Wang B, Tai PC. SecA inhibitors as potential antimicrobial agents: differential actions on SecA-only and SecA-SecYEG protein-conducting channels. FEMS Microbiol Lett 2018; 365:5037921. [PMID: 30007321 PMCID: PMC7190897 DOI: 10.1093/femsle/fny145] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 06/13/2018] [Indexed: 12/13/2022] Open
Abstract
Sec-dependent protein translocation is an essential process in bacteria. SecA is a key component of the translocation machinery and has multiple domains that interact with various ligands. SecA acts as an ATPase motor to drive the precursor protein/peptide through the SecYEG protein translocation channels. As SecA is unique to bacteria and there is no mammalian counterpart, it is an ideal target for the development of new antimicrobials. Several reviews detail the assays for ATPase and protein translocation, as well as the search for SecA inhibitors. Recent studies have shown that, in addition to the SecA-SecYEG translocation channels, there are SecA-only channels in the lipid bilayers, which function independently from the SecYEG machinery. This mini-review focuses on recent advances on the newly developed SecA inhibitors that allow the evaluation of their potential as antimicrobial agents, as well as a fundamental understanding of mechanisms of SecA function(s). These SecA inhibitors abrogate the effects of efflux pumps in both Gram-positive and Gram-negative bacteria. We also discuss recent findings that SecA binds to ribosomes and nascent peptides, which suggest other roles of SecA. A model for the multiple roles of SecA is presented.
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Affiliation(s)
- Jinshan Jin
- Department of Biology, Center for Biotechnology and Drug Design and Georgia State University, Atlanta, GA 30303, USA
| | - Ying-Hsin Hsieh
- Department of Biology, Center for Biotechnology and Drug Design and Georgia State University, Atlanta, GA 30303, USA
| | - Arpana S Chaudhary
- Department of Chemistry, Center for Biotechnology and Drug Design and Georgia State University, P.O. Box 3965, Atlanta, GA 30303, USA
| | - Jianmei Cui
- Department of Chemistry, Center for Biotechnology and Drug Design and Georgia State University, P.O. Box 3965, Atlanta, GA 30303, USA
| | - John E Houghton
- Department of Biology, Center for Biotechnology and Drug Design and Georgia State University, Atlanta, GA 30303, USA
| | - Sen-fang Sui
- State Key Laboratory of Membrane Biology, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Binghe Wang
- Department of Chemistry, Center for Biotechnology and Drug Design and Georgia State University, P.O. Box 3965, Atlanta, GA 30303, USA
| | - Phang C Tai
- Department of Biology, Center for Biotechnology and Drug Design and Georgia State University, Atlanta, GA 30303, USA
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Hsieh YH, Huang YJ, Zhang H, Liu Q, Lu Y, Yang H, Houghton J, Jiang C, Sui SF, Tai PC. Dissecting structures and functions of SecA-only protein-conducting channels: ATPase, pore structure, ion channel activity, protein translocation, and interaction with SecYEG/SecDF•YajC. PLoS One 2017; 12:e0178307. [PMID: 28575061 PMCID: PMC5456053 DOI: 10.1371/journal.pone.0178307] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 05/10/2017] [Indexed: 11/30/2022] Open
Abstract
SecA is an essential protein in the major bacterial Sec-dependent translocation pathways. E. coli SecA has 901 aminoacyl residues which form multi-functional domains that interact with various ligands to impart function. In this study, we constructed and purified tethered C-terminal deletion fragments of SecA to determine the requirements for N-terminal domains interacting with lipids to provide ATPase activity, pore structure, ion channel activity, protein translocation and interactions with SecYEG-SecDF•YajC. We found that the N-terminal fragment SecAN493 (SecA1-493) has low, intrinsic ATPase activity. Larger fragments have greater activity, becoming highest around N619-N632. Lipids greatly stimulated the ATPase activities of the fragments N608-N798, reaching maximal activities around N619. Three helices in amino-acyl residues SecA619-831, which includes the "Helical Scaffold" Domain (SecA619-668) are critical for pore formation, ion channel activity, and for function with SecYEG-SecDF•YajC. In the presence of liposomes, N-terminal domain fragments of SecA form pore-ring structures at fragment-size N640, ion channel activity around N798, and protein translocation capability around N831. SecA domain fragments ranging in size between N643-N669 are critical for functional interactions with SecYEG-SecDF•YajC. In the presence of liposomes, inactive C-terminal fragments complement smaller non-functional N-terminal fragments to form SecA-only pore structures with ion channel activity and protein translocation ability. Thus, SecA domain fragment interactions with liposomes defined critical structures and functional aspects of SecA-only channels. These data provide the mechanistic basis for SecA to form primitive, low-efficiency, SecA-only protein-conducting channels, as well as the minimal parameters for SecA to interact functionally with SecYEG-SecDF•YajC to form high-efficiency channels.
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Affiliation(s)
- Ying-hsin Hsieh
- Department of Biology, Center for Biotechnology and Drug Design, Georgia State University, Atlanta, GA, United States of America
| | - Ying-ju Huang
- Department of Biology, Center for Biotechnology and Drug Design, Georgia State University, Atlanta, GA, United States of America
| | - Hao Zhang
- Department of Biology, Center for Biotechnology and Drug Design, Georgia State University, Atlanta, GA, United States of America
| | - Qian Liu
- Department of Biology, Center for Biotechnology and Drug Design, Georgia State University, Atlanta, GA, United States of America
| | - Yang Lu
- Department of Biology, Center for Biotechnology and Drug Design, Georgia State University, Atlanta, GA, United States of America
| | - Hsiuchin Yang
- Department of Biology, Center for Biotechnology and Drug Design, Georgia State University, Atlanta, GA, United States of America
| | - John Houghton
- Department of Biology, Center for Biotechnology and Drug Design, Georgia State University, Atlanta, GA, United States of America
| | - Chun Jiang
- Department of Biology, Center for Biotechnology and Drug Design, Georgia State University, Atlanta, GA, United States of America
| | - Sen-Fang Sui
- State Key Laboratory of Membrane Biology, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing China
| | - Phang C. Tai
- Department of Biology, Center for Biotechnology and Drug Design, Georgia State University, Atlanta, GA, United States of America
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Hsieh YH, Zhang H, Jin J, Dai C, Jiang C, Wang B, Tai PC. Biphasic actions of SecA inhibitors on Prl/Sec suppressors: Possible physiological roles of SecA-only channels. Biochem Biophys Res Commun 2017; 482:296-300. [PMID: 27856243 DOI: 10.1016/j.bbrc.2016.11.057] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 11/11/2016] [Indexed: 11/30/2022]
Abstract
SecA is an essential component in the bacterial Sec-dependent protein translocation process. We previously showed that in addition to the ubiquitous, high-affinity SecYEG-SecDF·YajC protein translocation channel, there is a low-affinity SecA-only channel that elicits ion channel activity and promotes protein translocation. The SecA-only channels are less efficient, and like Prl suppressors, lack signal peptide specificity; they function in the absence of signal peptides. The presence of SecYEG-SecDF·YajC alters the sensitivity of ATPase inhibitor Rose Bengal. In this study, we found that the suppressor membranes are much more resistant to inhibition by Rose Bengal. Similar results have been found for a SecA-specific inhibitor. Moreover, biphasic responses of inhibition of ion current and protein translocation activities were observed for many PrlA/SecY and PrlG/SecE suppressor membranes, with a low IC50 value similar to that of the SecA-only channels and a very high IC50. However, the suppressor strains are as sensitive to the inhibitor as the parental strain, suggesting that SecA-only channels have some essential physiological function(s) in the cells that are inhibited by the specific SecA inhibitor.
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Affiliation(s)
- Ying-Hsin Hsieh
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA
| | - Hao Zhang
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA
| | - Jinshan Jin
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA
| | - Chaofeng Dai
- Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA
| | - Chun Jiang
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA
| | - Binghe Wang
- Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA
| | - Phang C Tai
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA; Center for Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303, USA.
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Hsieh YH, Huang YJ, Jin JS, Yu L, Yang H, Jiang C, Wang B, Tai PC. Mechanisms of Rose Bengal inhibition on SecA ATPase and ion channel activities. Biochem Biophys Res Commun 2014; 454:308-12. [PMID: 25450394 DOI: 10.1016/j.bbrc.2014.10.070] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 10/14/2014] [Indexed: 10/24/2022]
Abstract
SecA is an essential protein possessing ATPase activity in bacterial protein translocation for which Rose Bengal (RB) is the first reported sub-micromolar inhibitor in ATPase activity and protein translocation. Here, we examined the mechanisms of inhibition on various forms of SecA ATPase by conventional enzymatic assays, and by monitoring the SecA-dependent channel activity in the semi-physiological system in cells. We build on the previous observation that SecA with liposomes form active protein-conducting channels in the oocytes. Such ion channel activity is enhanced by purified Escherichia coli SecYEG-SecDF·YajC liposome complexes. Inhibition by RB could be monitored, providing correlation of in vitro activity and intact cell functionality. In this work, we found the intrinsic SecA ATPase is inhibited by RB competitively at low ATP concentration, and non-competitively at high ATP concentrations while the translocation ATPase with precursors and SecYEG is inhibited non-competitively by RB. The Inhibition by RB on SecA channel activity in the oocytes with exogenous ATP-Mg(2+), mimicking translocation ATPase activity, is also non-competitive. The non-competitive inhibition on channel activity has also been observed with SecA from other bacteria which otherwise would be difficult to examine without the cognate precursors and membranes.
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Affiliation(s)
- Ying-Hsin Hsieh
- Department of Biology, Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303, United States
| | - Ying-Ju Huang
- Department of Biology, Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303, United States
| | - Jin-Shan Jin
- Department of Biology, Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303, United States
| | - Liyan Yu
- Department of Biology, Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303, United States
| | - Hsiuchin Yang
- Department of Biology, Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303, United States
| | - Chun Jiang
- Department of Biology, Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303, United States
| | - Binghe Wang
- Department of Chemistry, Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303, United States
| | - Phang C Tai
- Department of Biology, Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303, United States.
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