Biochemical Comparison of Pili from Variants of Neisseria gonorrhoeae P9

Abstract

Four different types of pili produced by variants of N. gonorrhoeae P9 were isolated and characterized. The pili differed in subunit MW with SDS-PAGE [sodium dodecyl sulfate- polyacrylamide gel electrophoresis] and in subunit isoelectric point on agarose gels. Isoelectric points [pI] of the major molecular species in Triton-agarose gels of octylglucoside solubilized pili were: .delta., pI 6.5; .alpha., pI 6.0; .beta., pI 5.3 and .gamma., pI 5.5. Amino acid analyses of pili showed close homology between different types but a reduction in the content of aspartate and serine was notable in the low MW .delta. pili; .beta. and .gamma. pili contained more alanine residues. Structural homology was also demonstrated in peptide maps of tryptic/chymotryptic digests of pili with several major peptides apparently common to all 4 pilus types.