Cloning, sequencing, and transcriptional studies of the gene encoding copper-containing nitrite reductase from Alcaligenes xylosoxidans NCIMB 11015

Gene encoding of the blue copper-containing nitrite reductase (nir) from Al caligenes xylosoxidans NCIMB 11015 has been cloned and characterized. The n ir is translated into a polypeptide of 360 amino acid residues as a precurs or, and the N-terminal 24 residues are subsequently removed upon transport into the periplasm as a mature protein. A specific transcription product of nir was detected only in the presence of nitrate. The aeration level of th e culture medium did not show a significant effect on the transcriptional l evel. A sigma(54) binding sequence is identified upstream of the transcript ional initiation at 53 to 26 nucleotides. A putative fnr box has also been identified in the sequence of the upstream region. The mature polypeptide s howed 70% sequence identity with those of the Achromobacter cycloclastes en zyme. The transcrip tional start point has been determined at 92 nucleo tid es upstream of the initiation codon and is preceded by the binding sites fo r sigma(54) and the fnr box. These results suggest that gene expression dep ends on the presence of nitrate and is stimulated under an anaerobic enviro nment. (C) 1999 Academic Press.