THE PATHOGENIC NEISSERIAE CONTAIN AN INACTIVE RPON GENE AND DO NOT UTILIZE THE PILE SIGMA(54) PROMOTER

The sigma(54) promoter (P3) upstream of the pilE gene in Neisseria gon orrhoeae was shown to be non-functional by transcriptional analysis of a PpilE::lacZ fusion containing only P3. A region on the chromosome o f N. gonorrhoeae strain MS11-A was identified that potentially encodes a protein with a significant similarity to the Escherichia coli RpoN protein. However, this region (designated RLS for rpoN-like sequence) does not contain a single open reading frame (ORF) capable of encoding a functional RpoN protein. It appears that RLS may have arisen from a n ancestral rpoN homologue that underwent a deletion removing the sequ ence encoding the essential helix-turn-helix (HTH) motif, and changing the subsequent reading frame. An RLS has been identified in several s trains of N. gonorrhoeae and N. meningitidis. A 90-kDa gonococcal prot ein has previously been shown to react with a monoclonal antibody rais ed against the RpoN from Salmonella typhimurium. However, mutagenesis and Western blot analysis confirmed that the gene encoding this protei n is not contained within RLS. (C) 1998 Elsevier Science B.V.