KEGG ENZYME: 1.14.18.10

ENZYME: 1.14.18.10

Entry

EC 1.14.18.10               Enzyme

Name

plant 4,4-dimethylsterol C-4alpha-methyl-monooxygenase;
SMO1 (gene name)

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

Sysname

24-methylidenecycloartanol,ferrocytochrome-b5:oxygen oxidoreductase (C-4alpha-methyl-hydroxylating)

Reaction(IUBMB)

24-methylidenecycloartanol + 6 ferrocytochrome b5 + 3 O2 + 6 H+ = 3beta-hydroxy-4beta,14alpha-dimethyl-9beta,19-cyclo-5alpha-ergost-24(241)-en-4alpha-carboxylate + 6 ferricytochrome b5 + 4 H2O (overall reaction) [RN:R12377];
(1a) 24-methylidenecycloartanol + 2 ferrocytochrome b5 + O2 + 2 H+ = 4alpha-(hydroxymethyl)-4beta,14alpha-dimethyl-9beta,19-cyclo-5alpha-ergost-24(241)-en-3beta-ol + 2 ferricytochrome b5 + H2O [RN:R12368];
(1b) 4alpha-(hydroxymethyl)-4beta,14alpha-dimethyl-9beta,19-cyclo-5alpha-ergost-24(241)-en-3beta-ol + 2 ferrocytochrome b5 + O2 + 2 H+ = 4alpha-formyl-4beta,14alpha-dimethyl-9beta,19-cyclo-5alpha-ergost-24(241)-en-3beta-ol + 2 ferricytochrome b5 + 2 H2O [RN:R12369];
(1c) 4alpha-formyl-4beta,14alpha-dimethyl-9beta,19-cyclo-5alpha-ergost-24(241)-en-3beta-ol + 2 ferrocytochrome b5 + O2 + 2 H+ = 3beta-hydroxy-4beta,14alpha-dimethyl-9beta,19-cyclo-5alpha-ergost-24(241)-en-4alpha-carboxylate + 2 ferricytochrome b5 + H2O [RN:R12370]

Reaction(KEGG)

R12368 R12369 R12370 R12377

Substrate

24-methylidenecycloartanol [CPD:C08830];
ferrocytochrome b5 [CPD:C00999];
O2 [CPD:C00007];
H+ [CPD:C00080];
4alpha-(hydroxymethyl)-4beta,14alpha-dimethyl-9beta,19-cyclo-5alpha-ergost-24(241)-en-3beta-ol;
4alpha-formyl-4beta,14alpha-dimethyl-9beta,19-cyclo-5alpha-ergost-24(241)-en-3beta-ol

Product

3beta-hydroxy-4beta,14alpha-dimethyl-9beta,19-cyclo-5alpha-ergost-24(241)-en-4alpha-carboxylate;
ferricytochrome b5 [CPD:C00996];
H2O [CPD:C00001];
4alpha-(hydroxymethyl)-4beta,14alpha-dimethyl-9beta,19-cyclo-5alpha-ergost-24(241)-en-3beta-ol;
4alpha-formyl-4beta,14alpha-dimethyl-9beta,19-cyclo-5alpha-ergost-24(241)-en-3beta-ol

Comment

This plant enzyme catalyses a step in the biosynthesis of sterols. It acts on the 4alpha-methyl group of the 4,4-dimethylated intermediate 24-methylidenecycloartanol and catalyses three successive oxidations, turning it into a carboxyl group. The carboxylate is subsequently removed by EC 1.1.1.418, plant 3beta-hydroxysteroid-4alpha-carboxylate 3-dehydrogenase (decarboxylating), which also catalyses the epimerization of the remaining 4beta-methyl into the 4alpha position. Unlike the fungal/animal enzyme EC 1.14.18.9, 4alpha-methylsterol monooxygenase, this enzyme is not able to remove the methyl group from C-4-monomethylated substrates. That activity is performed in plants by a second enzyme, EC 1.14.18.11, plant 4alpha-monomethylsterol monooxygenase.

History

EC 1.14.18.10 created 2019

Pathway

ec00100

Steroid biosynthesis

ec01100

Metabolic pathways

ec01110

Biosynthesis of secondary metabolites

Orthology

K14423

plant 4,4-dimethylsterol C-4alpha-methyl-monooxygenase

Genes

ATH:	AT4G12110(SMO1-1) AT4G22755 AT4G22756(SMO1-2)

ALY:	110226378 110226382 9310821

CRB:	111829641 111829642 17878277 17884650

CSAT:

104707512 104717801 104718035 104718036 104720179 104722765 104722766 104722767 104731224 104731225 104733374 104737226

EUS:	EUTSA_v10024722mg EUTSA_v10025849mg EUTSA_v10028846mg

BRP:	103853483 103860261 103860313

BNA:	106375731 106375734 106376550 106395025 106440893 106440900

BOE:	106323132 106323529 106326927

RSZ:	108819044 108822182 108826950

THJ:	104813000 104813925

CPAP:

110817604 110819441

CIT:

102610279

CIC:	CICLE_v10021364mg

PVY:	116125412 116128115 116128172

MINC:

123204022 123210056

TCC:	18606367 18614230 18614300 18614301 18614438

GRA:	105763824 105763825 105765153 105792123 105800261

GHI:	107890661 107896508 107919482 107919503 107926922 107931276 107936415 107945640 107945641 107946958

GAB:	108457103 108458635 108458637 108468960 108479411

HSYR:

120192020 120202626 120206712 120213721

DZI:	111289871 111305927 111306357 111315419

EGR:	104441851 104443730

GMX:	100785755 100793153 100793785

GSJ:	114367510 114393840 114396051 114412109

PVU:	PHAVU_008G076300g PHAVU_010G081300g

VRA:	106769322 106779599

VAR:	108324101 108328655

VUN:	114179939 114185995

VUM:	124828945 124846174

CCAJ:

109802330 109809965

APRC:

113850460 113852978

MTR:	11426366 25498869

TPRA:

123887250

CAM:	101498049 101499136

PSAT:

127074119 127127223 127130959

VVO:	131614309 131637420 131637564

LJA:

130711895

ADU:	107471219 107487621

AIP:	107623619 107630595

AHF:	112716478 112721686 112783349 112803654

LANG:

109333400 109350013

PCIN:

129288105 129311756 129321842

QSA:	O6P43_024284 O6P43_034150

FVE:	105351403 105352873

RCN:	112177775 112180715

PPER:

18778059 18785578

PMUM:

103331830 103337274 107881149

PAVI:

110753700 110773748

PDUL:

117618692 117629198

MDM:	103420445 103433067

MSYL:

126620118 126628621

PXB:	103930498 103938116 103958174 103962383

ZJU:	107430251 107435696

MNT:

21405990

CSAV:

115716028 115716029

CSV:

101211692

CMO:

103490939

BHJ:

120069239

MCHA:

111020420

CMAX:

111465081 111498458

CMOS:

111431186 111448229

CPEP:

111799947 111809922

RCU:	107262576 8288054

MEAN:

126679082 126687043 130015667

JCU:	105643118 105645947

HBR:	110631783 110645323 110647686 110658049

MESC:

110600473 110607085

POP:	18094413 7479230 7488901

PEU:	105128938 105132225 105132487

PALZ:

118028552 118036059 118041303

PNZ:	133681426 133684487 133700350

JRE:	108981850 109011030 118347633

CILL:

122282858 122289030

CAVE:

132175610 132176364

QSU:

111999469

QLO:

115972153

TWL:	119980425 120016721

VVI:

100255536

VRI:

117905901

SLY:	101262546 104649012

SPEN:

107003251 107026679

SOT:	102605717 102606141

SSTN:

125845263 125878424

SDUL:

129886681 129889921

CANN:

107866563 107873120

LBB:	132635036 132645703

NTA:	107798822 107809242 107810865 107828110

NSY:	104225605 104227542

NTO:	104085939 104115593

NAU:	109211816 109214418

INI:	109147072 109149049 109165996

ITR:	116015051 116029935 116030447

SIND:

105155669 105164199 105173233

OEU:	111366033 111386563 111391303 111398487

EGT:

105965684

SSPL:

121744924 121791764 121796398 121800156 121811001

SMIL:

131025862

SHIS:

125186824 125194210

APAN:

127240281 127252576 127255379

HAN:	110864319 110864321 110864322 110867780

ECAD:

122585370 122611201

LSV:

111918756

CCAV:

112521181 112526832 112527858

DCR:	108206019 108211255

CSIN:

114262038 114299562 114311978

RVL:	131309923 131333476

AEW:	130752757 130782611 130793079

BVG:	104892421 104892422

SOE:	110779099 110784397

CQI:	110684683 110702588 110719378 110729310 110729358

ATRI:

130804405

MOF:

131163729

NNU:	104611228 104611828

MING:

122077742 122085506

TSS:	122648006 122669732

PSOM:

113275150 113304814 113306673

OSA:	4331338 4349278

OBR:

102723086

OGL:	127753258 127768592

BDI:	100830254 100830279 100832018 100832062

ATS:	109735447 109742913 109743100 109752552 109759404

TDC:	119274638 119286504 119294101 119295277 119298075 119298399 119306308 119328285 119338387

TAES:

123051467 123085710 123086677 123089447 123091300 123096278 123100508 123105854 123107910 123125632 123127385 123161960 123162077 123181575

TUA:	125506347 125510783 125512642 125525429 125550745

LPER:

127294147 127297591 127308143

LRD:	124648424 124671406 124676848 124694335 124699427 124699687 124708784 124708790

SBI:	8062847 8069599 8071163 8077962

ZMA:	100217119 100282314

MFLO:

136482611 136493477 136534157 136539388 136539417

SITA:

101762442 101770857

SVS:	117840008 117859214

PVIR:

120647612 120651800 120673669 120686746 120688009 120691786 120693297 120707052

PHAI:

112873879 112877714 112882554 112894791 112898047 112902836

PDA:	103714140 103718600 103720910

EGU:	105033591 105035357 105042945

MUS:	103972099 103972632 103985734 103985805 103995011

ZOF:	121971199 121976464 121980898 121981501 121982993 121984786 121985379 122025017

DCT:

110101909

PEQ:

110036326

AOF:	109837083 109838522

MSIN:

131248396

NCOL:

116247288 116262006 116262605 116262607

ATR:

18441549

SMO:	SELMODRAFT_104109 SELMODRAFT_170047

PPP:	112279680 112281769

» show all

Reference

1 [PMID:8505296]

Authors

Pascal S, Taton M, Rahier A

Title

Plant sterol biosynthesis. Identification and characterization of two distinct microsomal oxidative enzymatic systems involved in sterol C4-demethylation.

Journal

J Biol Chem 268:11639-54 (1993)

Reference

2 [PMID:9240456]

Authors

Rahier A, Smith M, Taton M.

Title

The role of cytochrome b5 in 4alpha-methyl-oxidation and C5(6) desaturation of plant sterol precursors.

Journal

Biochem Biophys Res Commun 236:434-7 (1997)
DOI:10.1006/bbrc.1997.6974

Reference

3 [PMID:11707264]

Authors

Darnet S, Bard M, Rahier A

Title

Functional identification of sterol-4alpha-methyl oxidase cDNAs from Arabidopsis thaliana by complementation of a yeast erg25 mutant lacking sterol-4alpha-methyl oxidation.

Journal

FEBS Lett 508:39-43 (2001)
DOI:10.1016/S0014-5793(01)03002-2

Reference

4 [PMID:14653780]

Authors

Darnet S, Rahier A

Title

Plant sterol biosynthesis: identification of two distinct families of sterol 4alpha-methyl oxidases.

Journal

Biochem J 378:889-98 (2004)
DOI:10.1042/BJ20031572

Sequence

[ath:AT4G12110 AT4G22756 AT4G22755]