MOLECULAR-CLONING, DNA-SEQUENCE ANALYSIS, AND CHARACTERIZATION OF THE CORYNEBACTERIUM-DIPHTHERIAE DTXR HOMOLOG FROM BREVIBACTERIUM-LACTOFERMENTUM

A homolog of the Corynebacterium diphtheriae dtxR gene was isolated from Brevibacterium lactofermentum. The product of the B. lactofermentum dtxR gene was immunoreactive with polyclonal anti-DtxR antibodies and functioned as an iron-activated repressor capable of regulating the expression of P-galactosidase from a diphtheria tox promoter/operator transcriptional fusion in recombinant Escherichia coli. The extents of induction by increasing concentrations of the chelator 2,2'-dipyridyl were identical in cells expressing DtxR from either C. diphtheriae or B. lactofermentum.