Characterisation of the mob locus from Rhodobacter sphaeroides required for molybdenum cofactor biosynthesis

A clone carrying the mob locus from Rb. sphaeroides WS8 has been isolated from a cosmid library by Southern blotting with a probe covering the mob genes of Escherichia coli. The mob DNA has been subcloned and partially restores molybdoenzyme activities when transformed into E. coli mob strains. DNA sequence analysis of the subclone carrying the mob genes predicted at least 2 open reading frames. The mobA gene encodes protein FA whilst mobB encodes a nucleotide binding protein which has at least one extra domain relative to its E. coli counterpart.