The nirSTBM region coding for cytochrome cd1‐dependent nitrite respiration of Pseudomonas stutzeri consists of a cluster of mono‐, di‐, and tetraheme proteins

Abstract
Genes for respiratory nitrite reduction (denitrification) of Pseudomonas stutzeri are clustered within 7 kbp. A 4.6-kbp Hind III-Kpn I fragment carrying nirS, the structural gene for cytochrome cd 1, was sequenced. An open reading frame immediately downstream of nirScodes for a 22.8-kDa protein with four heme c-binding motifs. Mutagenesis of this gene causes an apparent defect in electron donation to cytochrome cd 1. Following this ORF are the structural genes for cytochrome c 552, cytochrome c 551, and ORF5 that codes for a 11.9-kDa monoheme protein. All cytochromes have a signal sequence for protein export.