Molecular cloning of the gene encoding Thiobacillus ferrooxidans Fe(II) oxidase. High homology of the gene product with HiPIP

Abstract

The amino-terminal sequence of Thiobacillus ferrooxidans Fe(II) oxidase (linked to cytochrome c552) was determined, and the iro gene that encodes this enzyme was cloned using degenerate oligonucleotides as a probe. The DNA sequence of a region (856 base pairs) which encompasses the iro gene revealed that the enzyme was encoded by a 273-base pair open reading frame and consists of 90 amino acids, including a possible 37-residue signal sequence. The iro gene seems to be transcribed independently of any other gene because the transcriptional products are 0.45 and 0.6 kilobases in size. Current protein databases revealed that the iro gene product is a new member of the high redox potential iron sulfur proteins, which generally function in electron transport but do not show enzymatic activity.