Entry
Name
4alpha-methylsterol monooxygenase;
methylsterol hydroxylase (ambiguous);
4-methylsterol oxidase (ambiguous);
4,4-dimethyl-5alpha-cholest-7-en-3beta-ol,hydrogen-donor:oxygen oxidoreductase (hydroxylating) (ambiguous);
methylsterol monooxygenase (ambiguous);
ERG25 (gene name);
MSMO1 (gene name);
4,4-dimethyl-5alpha-cholest-7-en-3beta-ol,ferrocytochrome-b5:oxygen oxidoreductase (hydroxylating) (ambiguous)
Class
Oxidoreductases;
Acting on paired donors, with incorporation or reduction of molecular oxygen;
With another compound as one donor, and incorporation of one atom of oxygen into the other donor
BRITE hierarchy
Sysname
4,4-dimethyl-5alpha-cholest-7-en-3beta-ol,ferrocytochrome-b5:oxygen oxidoreductase (C4alpha-methyl-hydroxylating)
Reaction(IUBMB)
4,4-dimethyl-5alpha-cholest-7-en-3beta-ol + 6 ferrocytochrome b5 + 3 O2 + 6 H+ = 3beta-hydroxy-4beta-methyl-5alpha-cholest-7-ene-4alpha-carboxylate + 6 ferricytochrome b5 + 4 H2O (overall reaction) [RN:
R10057 ];
(1a) 4,4-dimethyl-5alpha-cholest-7-en-3beta-ol + 2 ferrocytochrome b5 + O2 + 2 H+ = 4alpha-hydroxymethyl-4beta-methyl-5alpha-cholest-7-en-3beta-ol + 2 ferricytochrome b5 + H2O [RN:
R04501 ];
(1b) 4alpha-hydroxymethyl-4beta-methyl-5alpha-cholest-7-en-3beta-ol + 2 ferrocytochrome b5 + O2 + 2 H+ = 3beta-hydroxy-4beta-methyl-5alpha-cholest-7-ene-4alpha-carbaldehyde + 2 ferricytochrome b5 + 2 H2O [RN:
R05733 ];
(1c) 3beta-hydroxy-4beta-methyl-5alpha-cholest-7-ene-4alpha-carbaldehyde + 2 ferrocytochrome b5 + O2 + 2 H+ = 3beta-hydroxy-4beta-methyl-5alpha-cholest-7-ene-4alpha-carboxylate + 2 ferricytochrome b5 + H2O [RN:
R05734 ]
Reaction(KEGG)
Substrate
4,4-dimethyl-5alpha-cholest-7-en-3beta-ol [CPD:
C04530 ];
ferrocytochrome b5 [CPD:
C00999 ];
O2 [CPD:
C00007 ];
H+ [CPD:
C00080 ];
4alpha-hydroxymethyl-4beta-methyl-5alpha-cholest-7-en-3beta-ol [CPD:
C04814 ];
3beta-hydroxy-4beta-methyl-5alpha-cholest-7-ene-4alpha-carbaldehyde [CPD:
C11509 ]
Product
3beta-hydroxy-4beta-methyl-5alpha-cholest-7-ene-4alpha-carboxylate [CPD:
C04840 ];
ferricytochrome b5 [CPD:
C00996 ];
H2O [CPD:
C00001 ];
4alpha-hydroxymethyl-4beta-methyl-5alpha-cholest-7-en-3beta-ol [CPD:
C04814 ];
3beta-hydroxy-4beta-methyl-5alpha-cholest-7-ene-4alpha-carbaldehyde [CPD:
C11509 ]
Comment
This enzyme is found in fungi and animals and catalyses a step in the biosynthesis of important sterol molecules such as ergosterol and cholesterol, respectively. The enzyme acts on the 4alpha-methyl group. Subsequent decarboxylation by EC
1.1.1.170 , 3beta-hydroxysteroid-4alpha-carboxylate 3-dehydrogenase (decarboxylating), occurs concomitantly with epimerization of the remaining 4beta-methyl into the 4alpha position, thus making it a suitable substrate for a second round of catalysis. cf. EC
1.14.13.246 , 4beta-methylsterol monooxygenase; EC
1.14.18.10 , plant 4,4-dimethylsterol C-4alpha-methyl-monooxygenase; and EC
1.14.18.11 , plant 4alpha-monomethylsterol monooxygenase.
History
EC 1.14.18.9 created 1972 as EC 1.14.99.16, transferred 2002 to EC 1.14.13.72, transferred 2017 to EC 1.14.18.9, modified 2019
Pathway
ec01110 Biosynthesis of secondary metabolites
Orthology
K07750 methylsterol monooxygenase
Genes
OGA : 100946570(MSMO1) 100963672
CFA : 102153215 102154725 119868057 475491(MSMO1)
VLG : 121481576(MSMO1) 121481939 121483202 121485237 121501741
EJU : 114210190(MSMO1) 114211920
ZCA : 113910940 113925898(MSMO1) 118355980 118357008
MLX : 118002100 118022180(MSMO1)
MMYO : 118658212(MSMO1) 118670801
AJM : 119045728(MSMO1) 119052871
PDIC : 114491483 114503548(MSMO1)
ACHC : 115334463 115346251(MSMO1)
CPOO : 109309728(MSMO1) 109309860
PMUA : 114604004 114604312
XLA : 108704957(msmo1.L) 108706637(msmo1.S)
BGAR : 122940276 122940341
SANH : 107655978 107702386
CCAR : 109046545 109046546
OTW : 121844279(msmo1) 121844460
OGO : 124020867 124021427 124028478
AANG : 118226680 118228243
BBEL : 109475810 109475811
VPO : Kpol_414p6 Kpol_472p14
ZRO : ZYRO0B07172g ZYRO0B07744g
NCS : NCAS_0A02240(NCAS0A02240) NCAS_0A02420(NCAS0A02420)
NDI : NDAI_0D04170(NDAI0D04170) NDAI_0D04450(NDAI0D04450)
TPF : TPHA_0B02330(TPHA0B02330) TPHA_0F01110(TPHA0F01110)
TBL : TBLA_0D02010(TBLA0D02010)
TDL : TDEL_0E01410(TDEL0E01410) TDEL_0E01680(TDEL0E01680)
TGB : HG536_0E01240 HG536_0E01500
KAF : KAFR_0F04030(KAFR0F04030) KAFR_0G03150(KAFR0G03150)
ZMK : HG535_0B06210 HG535_0F01540
DHA : DEHA2A12210g DEHA2G02640g
PIC : PICST_74706(ERG25) PICST_78360
PGU : PGUG_01908 PGUG_05253
SPAA : SPAPADRAFT_134612(SUR2.2) SPAPADRAFT_62633(ERG25)
LEL : LELG_00075 LELG_04249
CAL : CAALFM_C401530CA(ERG251) CAALFM_CR02370WA(ERG25)
CTP : CTRG_00198 CTRG_00908
COT : CORT_0A01460 CORT_0E01010
CDU : CD36_27330 CD36_41530
CTEN : CANTEDRAFT_109226(ERG25) CANTEDRAFT_131473(SUR2.2)
CLU : CLUG_00377 CLUG_02113
CLUS : A9F13_02g01804 A9F13_08g01859
PKZ : C5L36_0A11190 C5L36_0C08130
BNN : FOA43_001266(ERG25_1) FOA43_003536(ERG25_2)
BBRX : BRETT_002413(ERG25)
NTE : NEUTE1DRAFT116421(NEUTE1DRAFT_116421)
AFM : AFUA_4G04820 AFUA_8G02440
ACT : ACLA_043620 ACLA_067970
AOR : AO090010000667 AO090206000001
ANG : ANI_1_798034(An03g06410)
ALUC : AKAW2_40689A(ERG25) AKAW2_50990S
APUU : APUU_10643A(ERG25_1) APUU_21878S APUU_80630A(ERG25_3)
PCS : Pc13g05570 Pc21g21280
URE : UREG_02575 UREG_07066
ZTR : MYCGRDRAFT_36271(ERG25)
HIR : HETIRDRAFT_148092(smo1)
FME : FOMMEDRAFT_117464 FOMMEDRAFT_159067
LBC : LACBIDRAFT_182669(ERG25p-2)
ABP : AGABI1DRAFT115836(AGABI1DRAFT_115836)
ABV : AGABI2DRAFT228680(AGABI2DRAFT_228680)
» show all
Taxonomy
Reference
Authors
Miller WL, Kalafer ME, Gaylor JL, Delwiche CV.
Title
Investigation of the component reactions of oxidative sterol demethylation. Study of the aerobic and anaerobic processes.
Journal
Reference
Authors
Gaylor JL, Mason HS.
Title
Investigation of the component reactions of oxidative sterol demethylation. Evidence against participation of cytochrome P-450.
Journal
J Biol Chem 243:4966-72 (1968)
Reference
Authors
Sharpless KB, Snyder TE, Spencer TA, Maheshwari KK, Nelson JA
Title
Biological demethylation of 4,4-dimethyl sterols, Evidence for enzymic epimerization of the 4beta-methyl group prior to its oxidative removal.
Journal
Reference
Authors
Brady DR, Crowder RD, Hayes WJ
Title
Mixed function oxidases in sterol metabolism. Source of reducing equivalents.
Journal
J Biol Chem 255:10624-9 (1980)
Reference
Authors
Fukushima H, Grinstead GF, Gaylor JL
Title
Total enzymic synthesis of cholesterol from lanosterol. Cytochrome b5-dependence of 4-methyl sterol oxidase.
Journal
J Biol Chem 256:4822-6 (1981)
Reference
Authors
Kawata S, Trzaskos JM, Gaylor JL.
Title
Affinity chromatography of microsomal enzymes on immobilized detergent-solubilized cytochrome b5.
Journal
J Biol Chem 261:3790-9 (1986)
Other DBs
ExPASy - ENZYME nomenclature database: 1.14.18.9
LinkDB
All DBs