Figure 1. Presence of ChoP on pili in pathogenic N. meningitidis and its mediation by phase variation of the transferase, PptA.

A) Sequencing of the polymeric (G) tract region of various N. meningitidis strains and mutants with altered tract lengths. ON and OFF, respectively, indicate whether the gene is in-frame or out of frame for expression of a functional protein (translation of in-frame sequence shown under nucleotide sequence), ChoP PTM on pili from these strains is indicated as being present (+) or absent (−). B) Western blotting demonstrates the presence of ChoP on N. meningitidis pili and (C) the effect of changes in tract length on PptA function. Collectively, these data show that pili of N. meningitidis can only be modified with ChoP when the pptA polymeric repeat tract contains 8 glycines.