MetaCyc Enzyme: 3α-hydroxysteroid dehydrogenase 3

Gene: baiA3 Accession Number: G-142 (MetaCyc)

Species: Clostridium scindens VPI 12708

The experimentally determined subunit structure of this enzyme has not been reported.

In Clostridium scindens VPI 12708 (previously known as Eubacterium sp. strain VPI 12708) three separate genes, baiA1, baiA2 and baiA3 encode 3α-hydroxysteroid dehydrogenases that catalyze the second reaction in the bile acid 7α-dehydroxylation pathway. The physiological significance of the three separate isozymes is unclear. Genes baiA1 and baiA3 are monocistronic, while gene baiA2 is part of a bile acid-inducible bai operon in this organism. Genes baiA1 and baiA3 are identical in nucleotide sequence in the coding region, while gene baiA2 shows 81% nucleotide sequence identity with baiA1 and baiA3. It has been suggested that baiA1 and baiA3 are the result of a stably maintained gene duplication in this organism [GopalSrivastava90]. All three genes are inducible by bile acids and show highly conserved promoter regions at the amino acid sequence level, BaiA1 and BaiA3 are 100% identical. BaiA1 and BaiA2 have 92% amino acid sequence identity [Mallonee95, Hylemon98, Mallonee90].

The baiA1 gene has been cloned and overexpressed in Escherichia coli, partially purified and its kinetic properties studied [Mallonee95].

Molecular Weight of Polypeptide: 26.658 kD (from nucleotide sequence)

Isozyme Sequence Similarity:
3α-hydroxysteroid dehydrogenase 1: YES [Comment 1] ,
3α-hydroxysteroid dehydrogenase 2: YES [Comment 2]

Unification Links: Entrez-Nucleotide:M34658

Relationship Links: UniProt:PART-OF:P07914

Gene-Reaction Schematic: ?

Gene-Reaction Schematic

Revised 04-Jun-2010 by Fulcher CA , SRI International

Enzymatic reaction of: choloyl-CoA dehydrogenase (3α-hydroxysteroid dehydrogenase 3)

Synonyms: 3α-HSDH, 3α-hydroxysteroid dehydrogenase

choloyl-CoA + NAD(P)+ <=> 3-oxo-cholyl-CoA + NAD(P)H + H+

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction of enzyme catalysis.

This reaction is reversible.

In Pathways: cholate degradation (bacteria, anaerobic)


GopalSrivastava90: Gopal-Srivastava R, Mallonee DH, White WB, Hylemon PB (1990). "Multiple copies of a bile acid-inducible gene in Eubacterium sp. strain VPI 12708." J Bacteriol 172(8);4420-6. PMID: 2376563

Hylemon98: Hylemon PB, Harder J (1998). "Biotransformation of monoterpenes, bile acids, and other isoprenoids in anaerobic ecosystems." FEMS Microbiol Rev 1998;22(5);475-88. PMID: 9990726

Mallonee90: Mallonee DH, White WB, Hylemon PB (1990). "Cloning and sequencing of a bile acid-inducible operon from Eubacterium sp. strain VPI 12708." J Bacteriol 172(12);7011-9. PMID: 2254270

Mallonee95: Mallonee DH, Lijewski MA, Hylemon PB (1995). "Expression in Escherichia coli and characterization of a bile acid-inducible 3 alpha-hydroxysteroid dehydrogenase from Eubacterium sp. strain VPI 12708." Curr Microbiol 1995;30(5);259-63. PMID: 7766153

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 19.0 on Fri Oct 9, 2015, biocyc13.