Studies in FY'94 on structure and function of gonococcal surface components were continuations of previously-initiated attempts to describe biological behaviors of these organisms to the physicochemical attributes of their surfaces. Earlier results on electrophoretic characteristics of whole gonococci established that both lipooligosaccharide (LOS) and Opa outer membrane proteins exert individual and collective influences on cell surface charge. Some Opa proteins contribute positive charge on whole gonococci. Other Opa proteins greatly enhanced negativity in spite of their having abundant cationic amino acids in their (predicted) surface-exposed portions. This affect was shown to result from accretion of polyanions (such as DNA and sulfated polysaccharide) on cells that expressed certain Opa proteins. These Opa+ gonococci, in effect, acquire a """"""""garbage"""""""" capsule. Results also show that pilus+ cells are less negatively charged than their pilus- counterparts. Piliation 'dampens' influences of LOS, Opa, and polyanion accretion on cell charge, with pilus+ cells maintaining a net charge near zero, often slightly positive, regardless of the environment or which outer membrane components they express. Most recent studies indicate strict correlation between LOS side chain structure and gonococcal charge, with single sugar charges producing differences in whole cell electrophoretic mobilities A -2.1 to -0.2 micro m-cm/V-S. Gonococcal charge correlates with susceptibility to the oligopeptide magainin-2 which forms pores in bacterial membranes.
