Approximately one million cases of gonococcal infections will have occurred by the end of 1990 and based on current trends, it is likely that gonorrhea will remain a prevalent sexually transmitted disease for the next several years. This research program addresses the role of the human neutrophil in host defense against invading gonococci. We seek to understand how gonococci are killed by phagocytes in vitro so as to learn how they apparently develop resistance to killing during infection. Earlier studies showed that the nonoxidative antimicrobial capacity of lysosomal cathepsin G is an important determinant of phagocyte bactericidal action. We have identified different chromosomal mutations that modulate levels of gonococcal susceptibility to cathepsin G and a synthetic antibacterial peptide derived from its sequence. Expression of these mutations results in hypersusceptibility of gonococci to cathepsin G by effecting either the binding of the bactericidal protein to the gonococcal surface or by altering an enzyme that complete peptidoglycan synthesis tat cell division. This enzyme is termed penicillin binding protein 2 (PBP 2) and it gives evidence of being the lethal target of cathepsin G action. Gonococcal susceptibility to cathepsin G is augmented by a mutation which increases the amount of a highly conserved, invariant 44 kDa outer membrane protein (OMP). Over-expression of this OMP also results in increased resistance of gonococci to several hydrophobic, clinically useful antibiotics. This OMP also gives evidence of being the major penicillin in binding protein (PBP 3) in gonococci. Two major goals of the current proposal are to define the sequence of this OMP and to ascertain how its synthesis is regulated. Determining the mechanism by which gonococci are killed by cathepsin G is the third goal of the proposal. Past studies suggest that cathepsin G is third goal of the proposal. Past studies suggest that cathepsin G forms a complex with PBP 2, a periplasmic protein anchored to the cytoplasmic membrane. Using isogenic strains that differ in levels of susceptibility to cathepsin G and contemporary techniques in molecular biology and genetics, experiments will be conducted to determine susceptibility also increase gonococcal resistance to antibiotics, the results will advance our knowledge regarding the mechanisms by which gonococci have evolved resistance to clinically useful antimicrobial agents.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
Project #
Application #
Study Section
Bacteriology and Mycology Subcommittee 2 (BM)
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Emory University
Schools of Medicine
United States
Zip Code
Ohneck, Elizabeth A; Goytia, Maira; Rouquette-Loughlin, Corinne E et al. (2015) Overproduction of the MtrCDE efflux pump in Neisseria gonorrhoeae produces unexpected changes in cellular transcription patterns. Antimicrob Agents Chemother 59:724-6
Unemo, Magnus; Shafer, William M (2015) Future treatment of gonorrhea--novel emerging drugs are essential and in progress? Expert Opin Emerg Drugs 20:357-60
Bauer, Margaret E; Shafer, William M (2015) On the in vivo significance of bacterial resistance to antimicrobial peptides. Biochim Biophys Acta 1848:3101-11
Johnson, Paul J T; Shafer, William M (2015) The Transcriptional Repressor, MtrR, of the mtrCDE Efflux Pump Operon of Neisseria gonorrhoeae Can Also Serve as an Activator of ""off Target"" Gene (glnE) Expression. Antibiotics (Basel) 4:188-97
Unemo, Magnus; Golparian, Daniel; Shafer, William M (2014) Challenges with gonorrhea in the era of multi-drug and extensively drug resistance - are we on the right track? Expert Rev Anti Infect Ther 12:653-6
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
Zalucki, Yaramah M; Dhulipala, Vijaya; Shafer, William M (2012) Dueling regulatory properties of a transcriptional activator (MtrA) and repressor (MtrR) that control efflux pump gene expression in Neisseria gonorrhoeae. MBio 3:e00446-12
Unemo, Magnus; Shafer, William M (2011) Antibiotic resistance in Neisseria gonorrhoeae: origin, evolution, and lessons learned for the future. Ann N Y Acad Sci 1230:E19-28
Ohneck, Elizabeth A; Zalucki, Yaramah M; Johnson, Paul J T et al. (2011) A novel mechanism of high-level, broad-spectrum antibiotic resistance caused by a single base pair change in Neisseria gonorrhoeae. MBio 2:
Kamal, Nazia; Shafer, William M (2010) Biologic activities of the TolC-like protein of Neisseria meningitidis as assessed by functional complementation in Escherichia coli. Antimicrob Agents Chemother 54:506-8

Showing the most recent 10 out of 71 publications