The σ54 promoter (P3) upstream of the pilE gene in Neisseria gonorrhoeae was shown to be non-functional by transcriptional analysis of a PpilE::lacZ fusion containing only P3. A region on the chromosome of 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 an ancestral rpoN homologue that underwent a deletion removing the sequence encoding the essential helix-turn-helix (HTH) motif, and changing the subsequent reading frame. An RLS has been identified in several strains of N. gonorrhoeae and N. meningitidis. A 90-kDa gonococcal protein has previously been shown to react with a monoclonal antibody raised against the RpoN from Salmonella typhimurium. However, mutagenesis and Western blot analysis confirmed that the gene encoding this protein is not contained within RLS.
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