IDENTIFICATION AND CLONING OF A FUR HOMOLOG FROM NEISSERIA-GONORRHOEAE

The promoter region of the major iron-regulated protein of Neisseria g onorrhoeae, Fbp, has two regions that exhibit homology with the Escher ichia coli consensus Fur-binding sequences. Gel retardation assays sug gested that purified E. coli Fur bound to two sites within the Fbp pro moter. The presence of a gonococcal Fur homolog was suggested by South ern hybridization under conditions of low stringency, which revealed a DNA locus that exhibited homology to the E. coli fur gene. Oligonucle otides derived from the conserved regions of fur genes of extremely di verse bacteria were used to amplify a 140-bp fragment of a putative go nococcal fur gene. This fragment was used to identify clones containin g the entire gonococcal fur gene. After sequencing the gonococcal fur gene and its promoter region, we found that gonococcal Fur exhibited 5 0% identity with E. coli Fur at the amino acid level; however, it comp lemented two E. coli Fur- mutants. The presence of a Fur homolog in N. gonorrhoeae suggests that Fur-regulated genes are widely distributed among extremely diverse bacteria.