KEGG   ENZYME: 1.1.1.417Help
Entry
EC 1.1.1.417                Enzyme                                 

Name
3beta-hydroxysteroid-4beta-carboxylate 3-dehydrogenase (decarboxylating);
sdmB (gene name)
Class
Oxidoreductases;
Acting on the CH-OH group of donors;
With NAD+ or NADP+ as acceptor
BRITE hierarchy
Sysname
3beta-hydroxysteroid-4beta-carboxylate:NAD(P)+ 3-oxidoreductase (decarboxylating)
Reaction(IUBMB)
a 3beta-hydroxy-4alpha-methylsteroid-4beta-carboxylate + NAD(P)+ = a 4alpha-methyl-3-oxosteroid + NAD(P)H + CO2 + H+ [RN:R12361 R12362]
Reaction(KEGG)
Substrate
3beta-hydroxy-4alpha-methylsteroid-4beta-carboxylate [CPD:C22106];
NAD+ [CPD:C00003];
NADP+ [CPD:C00006]
Product
4alpha-methyl-3-oxosteroid [CPD:C22107];
NADH [CPD:C00004];
NADPH [CPD:C00005];
CO2 [CPD:C00011];
H+ [CPD:C00080]
Comment
This bacterial enzyme participates in the biosynthesis of bacterial sterols. Together with EC 1.14.13.246, 4beta-methylsterol monooxygenase (SdmA) it forms an enzyme system that removes one methyl group from the C-4 position of 4,4-dimethylated steroid molecules. SdmA catalyses three successive oxidations of the C-4beta methyl group, turning it into a carboxylate group; SdmB is a bifunctional enzyme that catalyses two different activities. As EC 1.1.1.417 it catalyses an oxidative decarboxylation that results in reduction of the 3beta-hydroxy group at the C-3 carbon to an oxo group. As EC 1.1.1.270, 3beta-hydroxysteroid 3-dehydrogenase, it reduces the 3-oxo group back to a 3beta-hydroxyl. Since the remaining methyl group at C-4 is in an alpha orientation, it cannot serve as a substrate for a second round of demethylation by this system.
History
EC 1.1.1.417 created 2019
Orthology
K23557  3beta-hydroxysteroid-4beta-carboxylate 3-dehydrogenase (decarboxylating)
Genes
MCA: MCA1017
MMAI: sS8_3008
SAMY: DB32_006294
MRM: A7982_00876
Taxonomy
Reference
1  [PMID:29784781]
  Authors
Lee AK, Banta AB, Wei JH, Kiemle DJ, Feng J, Giner JL, Welander PV
  Title
C-4 sterol demethylation enzymes distinguish bacterial and eukaryotic sterol synthesis.
  Journal
Proc Natl Acad Sci U S A 115:5884-5889 (2018)
DOI:10.1073/pnas.1802930115
  Sequence
[mca:MCA1017]
Other DBs
ExplorEnz - The Enzyme Database: 1.1.1.417
IUBMB Enzyme Nomenclature: 1.1.1.417
ExPASy - ENZYME nomenclature database: 1.1.1.417
BRENDA, the Enzyme Database: 1.1.1.417

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