During early stages of growth, synthesizes a hyphae-associated, haem-containing enzyme which exhibits catalase and peroxidase activities with broad substrate specificity (CpeB). The purified dimeric enzyme (160 kDa) consists of two identical subunits. Using anti-CpeB antibodies and an expression- as well as a mini-library, the corresponding gene was identified and sequenced. It encodes a protein of 740 aa with a molecular mass of 81·3 kDa. The deduced protein shares the highest level of amino acid identity with KatG from and and PerA from transformants carrying and the upstream-located gene with its regulatory region on the bifunctional vector pWHM3 produced low or enhanced levels of CpeB in the presence or absence of Fe ions, respectively. An in-frame deletion of the major part of induces increased CpeB synthesis. The data imply that FurS regulates the transcription of The deduced FurS protein is rich in histidine residues, contains a putative N-terminally situated helix-turn-helix motif and has a molecular mass of 15·1 kDa. It shares only 29% amino acid identity with the ferric uptake regulator (Fur) protein, but about 64% with FurA deduced from the genomic sequences of several mycobacteria. The predicated secondary structures of FurS and FurA are highly similar and considerably divergent from those of the Fur. In contrast to some Gram-negative bacteria, within several mycobacteria an intact gene or a pseudogene is upstream of a catalase-peroxidase () gene predicted to encode a functional or a non-functional () enzyme. Thus the data obtained for are expected to serve as an additional model to elucidate the regulation of mycobacterial catalase-peroxidase genes.


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