Literature summary extracted from

Ghosh, R.; Roth, E.; Abou-Aisha, K.; Saegesser, R.; Autenrieth, C.
The monofunctional cobalamin biosynthesis enzyme precorrin-3B synthase (CobZRR) is essential for anaerobic photosynthesis in Rhodospirillum rubrum but not for aerobic dark metabolism (2018), Microbiology, 164, 1416-1431 .

Cloned(Commentary)

EC Number	Cloned (Comment)	Organism
1.14.99.B11	gene cobZ, orf663, genetic organization, DNA and amino acid sequence determination and analysis, gene cobZ localizes to a 23.5 kb insert of chromosomal DNA contained on the cosmid pSC4, genetic mapping. pSC4 complements several mutants of bacteriochlorophyll and carotenoid biosynthesis, due to the presence of the bchCX and crtCDEF genes at one end of the cosmid insert, flanking cobZRR. In Rhodospirillum rubrum, the cobZ homologue is split into two separate but adjacent genes, cobZRR and citB/tcuB, and their products (CobZRR and CitB/TcuB) correspond to the N- and C-terminal regions of the enzyme protein. CobZRR encodes a fully functional CobZ homologue and the citB/tcuB gene plays no role in cobalamin biosynthesis in Rhodospirillum rubrum	Rhodospirillum rubrum

Protein Variants

EC Number	Protein Variants	Comment	Organism
1.14.99.B11	additional information	mutant SERGK25 containing a terminatorless kanamycin interposon inserted into cobZRR, cannot grow by anaerobic photosynthesis, but grows normally under dark, aerobic and microaerophilic conditions with succinate and fructose as carbon sources. The anaerobic in vivo activity of CobZ mutant indicates that it does not require oxygen as a substrate. The mutant excretes large amounts of protoporphyrin IX-monomethylester, a brown precursor of bacteriochlorophyll biosynthesis. The mutant is complemented either by the cobZRR gene in trans, or when exogenous cobalamin is added to the medium. A deletion mutant of tcuB/citB does not exhibit the cob phenotype. The chromosomal cobZRR gene is interrupted by site-directed interposon mutagenesis using a transcription terminatorless npt gene. A deletion mutant of the cob gene, cobZRR, is obtained by deleting a 0.3 kb SalI fragment in plasmid pBsSGE3, obtained after subcloning of the 2.7 kb insert from pBsSGE3 into pBsAG1	Rhodospirillum rubrum

Natural Substrates/ Products (Substrates)

EC Number	Natural Substrates	Organism	Comment (Nat. Sub.)	Natural Products	Comment (Nat. Pro.)	Rev.	Reac.
1.14.99.B11	additional information	Rhodospirillum rubrum	the anaerobic in vivo activity of CobZ indicates that it does not require oxygen as a substrate	?	-	-
1.14.99.B11	precorrin-3A + reduced acceptor	Rhodospirillum rubrum	-	precorrin-3B + acceptor	-	?

Organism

EC Number	Organism	UniProt	Comment	Textmining
1.14.99.B11	Rhodospirillum rubrum	-	-	-

Substrates and Products (Substrate)

EC Number	Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.	Reac.
1.14.99.B11	additional information	the anaerobic in vivo activity of CobZ indicates that it does not require oxygen as a substrate	Rhodospirillum rubrum	?	-	-
1.14.99.B11	precorrin-3A + reduced acceptor	-	Rhodospirillum rubrum	precorrin-3B + acceptor	-	?

Subunits

EC Number	Subunits	Comment	Organism
1.14.99.B11	More	the CobZRR domain corresponds to the true functional CobZ activity	Rhodospirillum rubrum

Synonyms

EC Number	Synonyms	Comment	Organism
1.14.99.B11	CdpA	-	Rhodospirillum rubrum
1.14.99.B11	CobZ	-	Rhodospirillum rubrum
1.14.99.B11	CobZRR	-	Rhodospirillum rubrum

Cofactor

EC Number	Cofactor	Comment	Organism	Structure
1.14.99.B11	flavin	probably	Rhodospirillum rubrum
1.14.99.B11	heme	probably	Rhodospirillum rubrum

General Information

EC Number	General Information	Comment	Organism
1.14.99.B11	malfunction	genotypic and phenotypic characterization of the cobZRR deletion mutant SERGK25, overview. mutant SERGK25 containing a terminatorless kanamycin interposon inserted into cobZRR, cannot grow by anaerobic photosynthesis, but grows normally under dark, aerobic and microaerophilic conditions with succinate and fructose as carbon sources. The anaerobic in vivo activity of CobZ mutant indicates that it does not require oxygen as a substrate. The mutant excretes large amounts of protoporphyrin IX-monomethylester, a brown precursor of bacteriochlorophyll biosynthesis. The mutant is complemented either by the cobZRR gene in trans, or when exogenous cobalamin is added to the medium. A deletion mutant of tcuB/citB does not exhibit the cob phenotype. Deletion of cobZ in the synthetic operon abolishes HBA synthesis, which is reversed by introducing the gene cobG, which encodes the precorrin-3B synthase (monooxygenase, EC 1.14.13.83) from Paracoccus denitrificans	Rhodospirillum rubrum
1.14.99.B11	metabolism	the monofunctional cobalamin biosynthesis enzyme precorrin-3B synthase (CobZRR) is essential for anaerobic photosynthesis in Rhodospirillum rubrum but not for aerobic dark metabolism. Essential role of the cob genes for cobalamin biosynthesis in anaerobic photoheterotrophic metabolism in a purple bacterium	Rhodospirillum rubrum
1.14.99.B11	additional information	the CobZRR domain corresponds to the true functional CobZ activity	Rhodospirillum rubrum
1.14.99.B11	physiological function	in the usual aerobic pathway, the ring contraction step [precorrin-3A to precorrin-3B] is catalyzed by cobG, which is not present in this organism. A flavoprotein encoded by the gene cobZ, when co-expressed in Escherichia coli with nine other cob genes (cobAEFHIKJLM) present on a synthetic operon, is able to perform the biosynthesis of hydrogenobyrinic acid (HBA) from endogenous uroporphyrinogen III. CobZRR encodes a fully functional CobZ homologue, while the citB/tcuB gene plays no role in cobalamin biosynthesis in Rhodospirillum rubrum. Gene cobZRR only is required for anaerobic photoheterotrophic growth of Rhodospirillum rubrum, and is essential for the biosynthesis of bacteriochlorophyll a (BChla). In contrast, cobZRR is not required for dark aerobic growth. Essential role of the cob genes for cobalamin biosynthesis in anaerobic photoheterotrophic metabolism in a purple bacterium	Rhodospirillum rubrum

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Release 2023.1 (January 2023)