ISOLATION, SEQUENCE AND EXPRESSION IN ESCHERICHIA-COLI OF THE NITRITEREDUCTASE GENE FROM THE FILAMENTOUS, THERMOPHILIC CYANOBACTERIUM PHORMIDIUM-LAMINOSUM

The nitrite reductase (NiR) gene (nirA) has been isolated and sequence d from the filamentous, thermophilic non-N-2-fixing cyanobacterium Pho rmidium laminosum. Putative promoter-like and Shine-Dalgarno sequences appear at the 5' end of the 1533 bp long nir-coding region. The deduc ed amino acid sequence of NiR from P. laminosum corresponds to a 56 kD a polypeptide, a size identical to the molecular mass previously deter mined for the pure enzyme, and shows a high identity with amino acid s equences from ferredoxin-dependent NiR. This cyanobacterial NiR gene h as been efficiently expressed in Escherichia coli DH5 alpha from the E . coli lac promoter and probably from the P. laminosum NiR promoter.