GONOCOCCAL SURFACE COMPONENTS--STRUCTURE AND FUNCTION

Niaid Extramural Activities

Investigators

Abstract

Work over the past year has extended previous studies on the comparataive susceptibilities of gonococci that possess different porin and Opa proteins in their outer membrane to polysulfated compounds such as heparin. Organisms that express no Opa protein are much more susceptible to growth-inhibition by heparin when they produce the Por1A form of porin than Opa- Por1B cells. When gonococci express an Opa protein, Por1A organisms become much more susceptible to heparin whereas Por1B bacteria become resistant. Porin polypeptides contain eight surface-exposed loop domains that each differs for Por1A versus Por1B. Organisms whose respective porin polypeptides are hybrid "mosaics" of Por1A/Por1B porins resemble Por1A (Opa+ more susceptible than Opa-) whenever their surface-exposed loop II and downstream portions are Por1A-like. Previous observations on men experimentally infected with Por1B gonococci disclosed that virtually all organisms shed from the urethra were Opa+. If susceptibility to heparin were instrumental in this differential survival of gonococci in vivo, then only Opa- variants should be found in clinical cultures of Por1A gonococci. Collaboration with Dr. J. Cannon (UNC) was established to explore that question in specimens that had been collected by UNC investigators from patients in a North Carolina county health clinic. But when Por1A gonococcal isolates were studied, the vast majority of isolated colonies displayed Opa+ phenotype that resembled findings with Por1B bacteria. Accordingly, although the affects of porin and Opa protein phenotypes on liabilities of goncoocci to polysulfated compounds is quite interesting, they have little apparent relavance to pathogenetic lifestyle of gonococci in the male urethra.