The Preparation and Properties of Gonococcal Pili

Abstract

Pili were isolated from Neisseria gonorrhoeae by controlled homogenization followed by selective disaggregation in sucrose and purification by CsCl density gradient centrifugation. Pili from 6 gonococcal strains had buoyant densities of 1.30-1.31 g ml-1 on CsCl. The pili were immunologically distinct when tested with rabbit antisera to purified pili. The amino acid composition of pilin from strains P9 and 201 was very similar, consisting of 208 and 212 amino acid residues, giving MW of 22,600 and 22,352, respectively. The pili contained a high proportion (46%) of non-polar amino acids. Further analysis of strain P9 pili revealed the presence of 1-2 phosphate groups and 1-2 hexose groups/pilin subunit; no amino sugars were detected. Pili from strain P9 were resolved into 2 bands by equilibrium density gradient centrifugation or column isoelectric focusing, suggesting the presence of more than 1 kind of pilus.