Colony opacity and protein II compositions of gonococci

Changes in the presence of outer membrane protein II (P.II) constituents of gonococci were demonstrated by selecting opacity variants and defining the 125I-labeled bands of parental and variant organisms. In general, colony opacity phenotype was a convenient, reliable guide for obtaining variants that differed from their parents by the apparent single-step gain or loss of one P.II constituent. Within a given strain (three strains were studied), particular P.II species were associated with particular opacity phenotypes. This was well demonstrated in strain JS3, in which five different P.II constituents were identified and compared. Four of these five P.II moieties were consistently associated with a characteristic degree of colony opacity: presence of the fifth P.II (P.IIa) did not correlate with a discernible increase in opacity when present either alone or in combination with other opacity-associated P.II moieties. The electrophoretic migration characteristics for each of the five P.II constituents of this strain differed with regard to apparent molecular weight and the effects of temperature and 2-mercaptoethanol. The high prevalence of colony opacity variants indicates that gonococcal populations are capable of presenting a variety of surface components to their external environment.