Neustria gonorrhoeae is a strict human pathogen that causes greater than sixty million cases worldwide of the sexually transmitted disease gonorrhea each year. Without an effective vaccine, antibiotic therapy remains the principle mechanism to reduce or block the transmission of the gonococcus in the community. Unfortunately, because of the development of mutations or the acquisition of resistance determinants, the gonococcus has developed resistance to relatively inexpensive antibiotics;such resistance now requires the use of more expensive antibiotics that are not always available in poor countries. Multidrug efflux pumps possessed by gonococci have an important role in the ability of gonococci to resist antibiotics and antimicrobials of the innate host defensive system. In particular, our work has shown that the MtrC-MtrD-MtrE efflux pump participates in gonococcal resistance to penicillin and macrolides. This efflux pump also recognizes host antimicrobials, such as antimicrobial peptides and progesterone. We have shown that the pump is required for gonococci to cause a sustained infection in experimentally-infected female mice and the degree of in vivo fitness is linked to transcriptional regulators that control mtrCDE gene expression. The importance of DNA- binding proteins in regulating gonococcal resistance to antimicrobials is the topic of this competitive renewal application.
In Specific Aim 1 we will define the transcriptional control processes that modulate expression of the mtrR gene, which encodes a repressor of the mtrCDE efflux pump operand and can control the expression of numerous genes outside of the mar locus. We will assess the importance of such regulation in the ability of gonococci to resist antimicrobials and during infection in experimentally-infected mice.
In Specific Aim 2 we will define the use, regulation and biologic importance of distinct promoters for transcription of the mtrCDE operand.
In Specific Aim 3 we will define the mechanism which the products of genes controlled by MtrR and other regulatory proteins impact levels of gonococcal susceptibility to antibiotics and host-derived antimicrobials. The results from the proposed work will advance our knowledge regarding how gonococci and other human bacterial pathogens use drug efflux pumps and transcriptional regulatory systems to resist both classical antibiotics as well as mediators of innate immunity.

Public Health Relevance

The goal of this project is to understand how Neustria gonorrhoeae uses drug efflux pumps and transcriptional regulators that control levels of efflux pumps and other structures to resist antibiotics or antimicrobials used by the human host during infection. The information gained will help in the development of new antimicrobials to treat or prevent gonorrhea, which remains a worldwide public health problem.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Method to Extend Research in Time (MERIT) Award (R37)
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Drug Discovery and Mechanisms of Antimicrobial Resistance Study Section (DDR)
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Hiltke, Thomas J
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Emory University
Schools of Medicine
United States
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Packiam, Mathanraj; Yedery, Roshan D; Begum, Afrin A et al. (2014) Phosphoethanolamine decoration of Neisseria gonorrhoeae lipid A plays a dual immunostimulatory and protective role during experimental genital tract infection. Infect Immun 82:2170-9
VĂ©lez Acevedo, Rosuany N; Ronpirin, Chalinee; Kandler, Justin L et al. (2014) Identification of regulatory elements that control expression of the tbpBA operon in Neisseria gonorrhoeae. J Bacteriol 196:2762-74
Bolla, Jani Reddy; Su, Chih-Chia; Do, Sylvia V et al. (2014) Crystal structure of the Neisseria gonorrhoeae MtrD inner membrane multidrug efflux pump. PLoS One 9:e97903
Golparian, Daniel; Shafer, William M; Ohnishi, Makoto et al. (2014) Importance of multidrug efflux pumps in the antimicrobial resistance property of clinical multidrug-resistant isolates of Neisseria gonorrhoeae. Antimicrob Agents Chemother 58:3556-9
Lei, Hsiang-Ting; Chou, Tsung-Han; Su, Chih-Chia et al. (2014) Crystal structure of the open state of the Neisseria gonorrhoeae MtrE outer membrane channel. PLoS One 9:e97475
Kandler, Justin L; Joseph, Sandeep J; Balthazar, Jacqueline T et al. (2014) Phase-variable expression of lptA modulates the resistance of Neisseria gonorrhoeae to cationic antimicrobial peptides. Antimicrob Agents Chemother 58:4230-3
Unemo, Magnus; Shafer, William M (2014) Antimicrobial resistance in Neisseria gonorrhoeae in the 21st century: past, evolution, and future. Clin Microbiol Rev 27:587-613
Cloward, Jason M; Shafer, William M (2013) MtrR control of a transcriptional regulatory pathway in Neisseria meningitidis that influences expression of a gene (nadA) encoding a vaccine candidate. PLoS One 8:e56097
Mercante, Alexandra Dubon; Jackson, Lydgia; Johnson, Paul J T et al. (2012) MpeR regulates the mtr efflux locus in Neisseria gonorrhoeae and modulates antimicrobial resistance by an iron-responsive mechanism. Antimicrob Agents Chemother 56:1491-501
Kunz, Anjali N; Begum, Afrin A; Wu, Hong et al. (2012) Impact of fluoroquinolone resistance mutations on gonococcal fitness and in vivo selection for compensatory mutations. J Infect Dis 205:1821-9

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