Isolation, sequence and expression in Escherichia coli of the nitrite reductase gene from the filamentous, thermophilic cyanobacterium Phormidium laminosum.

The nitrite reductase (NiR) gene (nirA) has been isolated and sequenced from the filamentous, thermophilic non-N2-fixing cyanobacterium Phormidium laminosum. Putative promoter-like and Shine-Dalgarno sequences appear at the 5' end of the 1533 bp long nir-coding region. The deduced amino acid sequence of NiR from P. laminosum corresponds to a 56 kDa polypeptide, a size identical to the molecular mass previously determined for the pure enzyme, and shows a high identity with amino acid sequences from ferredoxin-dependent NiR. This cyanobacterial NiR gene has been efficiently expressed in Escherichia coli DH5 alpha from the E. coli lac promoter and probably from the P. laminosum NiR promoter.