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-N-2-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.