The nrfI gene is essential for the attachment of the active site haem group of Wolinella succinogenes cytochrome c nitrite reductase
Abstract
The cytochrome c nitrite reductase complex (NrfHA) is the terminal enzyme in the electron transport chain catalysing nitrite respiration of Wolinella succinogenes. The catalytic subunit NrfA is a pentahaem cytochrome c containing an active site haem group which is covalently bound via the cysteine residues of a unique CWTCK motif. The lysine residue serves as the axial ligand of the haem iron. The other four haem groups of NrfA are bound by conventional haem-binding motifs (CXXCH). The nrfHAIJ locus was restored on the genome of the W. succinogenes DeltanrfAIJ deletion mutant by integration of a plasmid, thus enabling the expression of modified alleles of nrfA and nrfI. A mutant (K134H) was constructed which contained a nrfA gene encoding a CWTCH motif instead of CWTCK. NrfA of strain K134H was found to be synthesized with five bound haem groups, as judged by matrix-assisted laser-desorption/ionization (MALDI) mass spectrometry. Its nitrite reduction activity with reduced benzyl viologen was 40% of the wild-type activity. Ammonia was formed as the only product of nitrite reduction. The mutant did not grow by nitrite respiration and its electron transport activity from formate to nitrite was 5% of that of the wild-type strain. T...Continue Reading
References
A seven-gene operon essential for formate-dependent nitrite reduction to ammonia by enteric bacteria
Citations
Related Concepts
Related Feeds
Biosynthetic Transformations
Biosyntheic transformtions are multi-step, enzyme-catalyzed processes where substrates are converted into more complex products in living organisms. Simple compounds are modified, converted into other compounds, or joined together to form macromolecules. Discover the latest research on biosynthetic transformations here.
Bacterial Respiration
This feed focuses on cellular respiration in bacteria, known as bacterial respiration. Discover the latest research here.