title: Using Chemical Probes to Assess the Feasibility of Targeting SecA for Developing Antimicrobial Agents against Gram-Negative Bacteria.
abstract: With the widespread emergence of drug resistance, there is an urgent need to search for new antimicrobials, especially those against Gram-negative bacteria. Along this line, the identification of viable targets is a critical first step. The protein translocase SecA is commonly believed to be an excellent target for the development of broad-spectrum antimicrobials. In recent years, we developed three structural classes of SecA inhibitors that have proven to be very effective against Gram-positive bacteria. However, we have not achieved the same level of success against Gram-negative bacteria, despite the potent inhibition of SecA in enzyme assays by the same inhibitors. In this study, we use representative inhibitors as chemical probes to gain an understanding as to why these inhibitors were not effective against Gram-negative bacteria. The results validate our initial postulation that the major difference in effectiveness against Gram-positive and Gram-negative bacteria is in the additional permeability barrier posed by the outer membrane of Gram-negative bacteria. We also found that the expression of efflux pumps, which are responsible for multidrug resistance (MDR), have no effect on the effectiveness of these SecA inhibitors. Identification of an inhibitor-resistant mutant and complementation tests of the plasmids containing secA in a secAts mutant showed that a single secA-azi-9 mutation increased the resistance, providing genetic evidence that SecA is indeed the target of these inhibitors in bacteria. Such results strongly suggest SecA as an excellent target for developing effective antimicrobials against Gram-negative bacteria with the intrinsic ability to overcome MDR. A key future research direction should be the optimization of membrane permeability.
authors.affiliation: Department of Biology, Center for Biotechnology and Drug Design, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, 30303, USA.|US Food and Drug Administration, National Center of Toxicological Research, 3900 NCTR Road, Jefferson, AR, 72079, USA.
authors.forename: Jinshan
authors.initials: J
authors.lastname: Jin
authors.affiliation: Department of Biology, Center for Biotechnology and Drug Design, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, 30303, USA.
authors.forename: Ying-Hsin
authors.initials: YH
authors.lastname: Hsieh
authors.affiliation: Department of Chemistry, Center for Biotechnology and Drug Design, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, 30303, USA.
authors.forename: Jianmei
authors.initials: J
authors.lastname: Cui
authors.affiliation: Department of Chemistry, Center for Biotechnology and Drug Design, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, 30303, USA.
authors.forename: Krishna
authors.initials: K
authors.lastname: Damera
authors.affiliation: Department of Chemistry, Center for Biotechnology and Drug Design, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, 30303, USA.
authors.forename: Chaofeng
authors.initials: C
authors.lastname: Dai
authors.affiliation: Department of Chemistry, Center for Biotechnology and Drug Design, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, 30303, USA.
authors.forename: Arpana S
authors.initials: AS
authors.lastname: Chaudhary
authors.affiliation: Department of Biology, Center for Biotechnology and Drug Design, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, 30303, USA.
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Biology, Center for Biotechnology and Drug Design, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, 30303, USA.
authors.forename: Hsiuchin
authors.initials: H
authors.lastname: Yang
authors.affiliation: Department of Biology, Center for Biotechnology and Drug Design, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, 30303, USA.
authors.forename: Nannan
authors.initials: N
authors.lastname: Cao
authors.affiliation: Department of Biology, Center for Biotechnology and Drug Design, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, 30303, USA.
authors.forename: Chun
authors.initials: C
authors.lastname: Jiang
authors.affiliation: Division of Clinical Microbiology, Helsinki University Hospital, 00029 HUSLAB, Helsinki, Finland.|Northern Antibiotics Ltd., 00720, Helsinki, Finland.
authors.forename: Martti
authors.initials: M
authors.lastname: Vaara
authors.affiliation: Department of Chemistry, Center for Biotechnology and Drug Design, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, 30303, USA.
authors.forename: Binghe
authors.initials: B
authors.lastname: Wang
authors.affiliation: Department of Biology, Center for Biotechnology and Drug Design, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, 30303, USA.
authors.forename: Phang C
authors.initials: PC
authors.lastname: Tai
mesh_terms: D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000201:enzymology; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure; D000069816:SEC Translocation Channels / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000081416:SecA Proteins; D013329:Structure-Activity Relationship
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004791:Enzyme Inhibitors; D000069816:SEC Translocation Channels; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins
keywords: Gram-negative bacteria; SecA translocase; antibiotics; membrane permeability; multidrug resistance