FLAGELLAR GENES FROM RHODOBACTER-SPHAEROIDES ARE HOMOLOGOUS TO GENES OF THE FLIF OPERON OF SALMONELLA-TYPHIMURIUM AND TO THE TYPE-III SECRETION SYSTEM

A flagellar region of the genome of Rhodobacter sphaeroides was cloned and sequenced. Three ORFs were identified and arranged in the same or der as fliH, fliI and fliJ of Salmonella typhimurium (St). ORF2 is hig hly similar to FliI from St (49% similarity) showing Walker's A and B motifs. Similar scores were found with proteins of the type-III secret ion system of virulence factors. ORF3 shows 16.4 and 11.1% similarity to FliJ from St and Bacillus subtilis, respectively. This work also sh ows that ORF3 is similar to HrpJ5 from Pseudomonas syringae (19.2% sim ilarity). It was found that ORF2 and ORF3 start immediately downstream from the adjacent coding region, suggesting a single transcriptional unit.