Catalyzes the ATP-dependent amidation of the two carboxylate groups at positions a and c of cobyrinate, using either L-glutamine or ammonia as the nitrogen source. 2 ATP + cob(II)yrinate + 2 H2O + 2 L-glutamine = 2 ADP + cob(II)yrinate a,c diamide + 2 H+ + 2 L-glutamate + 2 phosphate .

MSAFYISAAHKSSGKTTLSIGLVRALRNRGLSLQTFKKGPDYIDPIWLSSASGNACYNLD FYTQHRREITELFQQYSSGPQVTLVEGNKGLYDGMDLQGEDCNAAMAKLLGLPVILVINA KGITRGVAPLLLGYQAFDPDVKIAGVILNQVSGPRHEIKLRRVVEHYTDIPLLGAVAADP QMVIDERHLGLKPSNEQSQAEAKINYLAEVLERQIDIEQLLESTVRAQVQALPSNAVETV QPFAGLRIGYPADTAFGFYYPDDMQAMQRLGAELLPFDSLHDSHLPAVDGLFLGGGFPET AMVELEANQPLLTEIKAFIEAGGPVYAECGGLMLLCRTLTWQGKTCRMAAVIPADAVMHE KPQGRGYIRLRETGAMPWPGAKTDAAPIHAHEFHYSALQGLDLAACTFAYRVERGTGIDG EHDGYIYKNLLANYAHMRSVGGNRWVERFLSHVRSCSRAEAP469

	PMID	Title & Author	Abstract	Year
0	16907720	Siro(haem)amide in Allochromatium vinosum and relevance of DsrL and DsrN, a homolog of cobyrinic acid a,c-diamide synthase, for sulphur oxidation.Yvonne J Lübbe , Hyung-Sun Youn, Russell Timkovich, Christiane Dah	In the purple sulphur bacterium Allochromatium vinosum, the prosthetic group of dissimilatory sulphite reductase (DsrAB) was identified as siroamide, an amidated form of the classical sirohaem. The genes dsrAB are the first two of a large cluster of genes necessary for the oxidation of sulphur globules stored intracellularly during growth on sulphide and thiosulphate. DsrN is homologous to cobyrinic acid a,c diamide synthase and may therefore catalyze glutamine-dependent amidation of sirohaem. Indeed, an A. vinosumDeltadsrN in frame deletion mutant showed a significantly reduced sulphur oxidation rate that was fully restored upon complementation with dsrN in trans. Sulphite reductase was still present in the DeltadsrN mutant. DsrL is a homolog of the small subunits of bacterial glutamate synthases and was proposed to deliver glutamine for sirohaem amidation. However, recombinant DsrL does not exhibit glutamate synthase activity nor does the gene complement a glutamate synthase-deficient Escherichia coli strain. Deletion of dsrL showed that the encoded protein is absolutely essential for sulphur oxidation in A. vinosum.	2006
1	10779710	Characterization of the desulforubidin operons from Desulfobacter vibrioformis and Desulfobulbus rhabdoformis.Larsen , T Lien, N K Birkeland	The genes encoding the desulforubidin type of dissimilatory sulfite reductase (Dsr) from the sulfate-reducing bacteria Desulfobacter vibrioformis and Desulfobulbus rhabdoformis were cloned and sequenced. Similar to the genes for dissimilatory sulfite reductase from the genera Archaeoglobus, Desulfovibrio and Desulfotomaculum the dsr genes were found to form an operon, dsrABD, where dsrA and dsrB encode the structural subunits, alpha and beta, of Dsr, respectively. dsrD encodes a conserved unknown protein apparently restricted to sulfate-reducing species. In Desulfobacter vibrioformis a fourth gene, designated dsrN, was found downstream of dsrD forming a contiguous operon, dsrABDN. DsrN showed significant sequence homology to cobyrinic a,c-diamide synthase, which is involved in the biosynthesis of vitamin B12. A function for DsrN in amidation of siroheme is likely. Analysis of the dsrAB-encoded proteins confirmed that the high conservation observed for other types of dissimilatory sulfite reductase is also found in desulforubidin. The use of Dsr sequences in unravelling the phylogeny of sulfate-reducing bacteria is discussed.	2000
2	11557144	A novel organization of the dissimilatory sulfite reductase operon of Thermodesulforhabdus norvegica verified by RT-PCR.Larsen Ø , T Lien, N K Birkeland	The nucleotide sequence of the gene cluster for the dissimilatory sulfite reductase (Dsr) from the Gram-negative thermophilic sulfate reducer Thermodesulforhabdus norvegica was determined. The Dsr-encoding genes (dsrAB) were found to be located in an operon encompassing four other open reading frames in the following order: dsrD-dsrA-dsrB-dsrN-dsrC-fdx. Localization of these six genes in the same operon supports previous suggestions that dsrD, -C and -N play essential roles in the mechanism for reduction of sulfite to sulfide. Transcriptional analysis showed that these genes constitute a contiguous transcriptional unit of at least 5 kb. The phylogeny of Dsr is discussed.	2001
3	29476143	Peatland Acidobacteria with a dissimilatory sulfur metabolism.Bela Hausmann , Claus Pelikan , Craig W Herbold , Stephan Köstlbacher, Mads Albertsen , Stephanie A Eichorst , Tijana Glavina Del Rio, Martin Huemer , Per H Nielsen , Thomas Rattei , Ulrich Stingl , Susannah G Tringe , Daniela Trojan , Cecilia Wentrup , Dagmar Woebken , Michael Pester , Alexander Loy	Sulfur-cycling microorganisms impact organic matter decomposition in wetlands and consequently greenhouse gas emissions from these globally relevant environments. However, their identities and physiological properties are largely unknown. By applying a functional metagenomics approach to an acidic peatland, we recovered draft genomes of seven novel Acidobacteria species with the potential for dissimilatory sulfite (dsrAB, dsrC, dsrD, dsrN, dsrT, dsrMKJOP) or sulfate respiration (sat, aprBA, qmoABC plus dsr genes). Surprisingly, the genomes also encoded DsrL, which so far was only found in sulfur-oxidizing microorganisms. Metatranscriptome analysis demonstrated expression of acidobacterial sulfur-metabolism genes in native peat soil and their upregulation in diverse anoxic microcosms. This indicated an active sulfate respiration pathway, which, however, might also operate in reverse for dissimilatory sulfur oxidation or disproportionation as proposed for the sulfur-oxidizing Desulfurivibrio alkaliphilus. Acidobacteria that only harbored genes for sulfite reduction additionally encoded enzymes that liberate sulfite from organosulfonates, which suggested organic sulfur compounds as complementary energy sources. Further metabolic potentials included polysaccharide hydrolysis and sugar utilization, aerobic respiration, several fermentative capabilities, and hydrogen oxidation. Our findings extend both, the known physiological and genetic properties of Acidobacteria and the known taxonomic diversity of microorganisms with a DsrAB-based sulfur metabolism, and highlight new fundamental niches for facultative anaerobic Acidobacteria in wetlands based on exploitation of inorganic and organic sulfur molecules for energy conservation.	2018

Lübbe, Y.J., Youn, H.S., Timkovich, R., and Dahl, C. (2006) Siro(haem)amide in Allochromatium vinosum and relevance of DsrL and DsrN, a homolog of cobyrinic acid a,c‐diamide synthase, for sulphur oxidation. FEMS Microbiol Lett 261: 194–202.