|Superclasses:||Reactions Classified By Conversion Type → Simple Reactions → Chemical Reactions → Protein-Modification Reactions|
|Reactions Classified By Substrate → Macromolecule Reactions → Protein-Reactions → Protein-Modification Reactions|
In Pathway: palmitate biosynthesis II (bacteria and plants)
Supersedes EC numbers: 184.108.40.206, 220.127.116.11, 18.104.22.168
Note that this reaction equation differs from the official Enzyme Commission reaction equations for this EC number.
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.
Mass balance status: Balanced.
Enzyme Commission Primary Name for 22.214.171.124: fatty-acyl-CoA synthase
Enzyme Commission Synonyms for 126.96.36.199: yeast fatty acid synthase, FAS1 (gene name), FAS2 (gene name)
Enzyme Commission Primary Name for 188.8.131.52: 3-hydroxyacyl-[acyl-carrier-protein] dehydratase
Enzyme Commission Synonyms for 184.108.40.206: fabZ (gene name), fabA (gene name), D-3-hydroxyoctanoyl-[acyl carrier protein] dehydratase, D-3-hydroxyoctanoyl-acyl carrier protein dehydratase, β-hydroxyoctanoyl-acyl carrier protein dehydrase, β-hydroxyoctanoyl thioester dehydratase, β-hydroxyoctanoyl-ACP-dehydrase, (3R)-3-hydroxyoctanoyl-[acyl-carrier-protein] hydro-lyase, (3R)-3-hydroxyoctanoyl-[acyl-carrier-protein] hydro-lyase (oct-2-enoyl-[acyl-carrier protein]-forming), 3-hydroxyoctanoyl-[acyl-carrier-protein] dehydratase
Enzyme Commission Summary for 220.127.116.11:
The enzyme from yeasts (Ascomycota and Basidiomycota) is a multi-functional protein complex composed of two subunits. One subunit catalyses the reactions EC 18.104.22.168, 3-oxoacyl-[acyl-carrier-protein] reductase and EC 22.214.171.124, β-ketoacyl-[acyl-carrier-protein] synthase I, while the other subunit catalyses the reactions of EC 126.96.36.199, [acyl-carrier-protein] S-acetyltransferase, EC 188.8.131.52, [acyl-carrier-protein] S-malonyltransferase, EC 184.108.40.206, 3-hydroxyacyl-[acyl-carrier-protein] dehydratase, EC 220.127.116.11, enoyl-[acyl-carrier-protein] reductase (NADPH, Si-specific) and EC 18.104.22.1689, (R)-3-hydroxyacid-ester dehydrogenase. The enzyme differs from the animal enzyme (EC 22.214.171.124) in that the enoyl reductase domain requires FMN as a cofactor, and the ultimate product is an acyl-CoA (usually palmitoyl-CoA) instead of a free fatty acid.
Enzyme Commission Summary for 126.96.36.199:
This enzyme is responsible for the dehydration step of the dissociated (type II) fatty-acid biosynthesis system that occurs in plants and bacteria. The enzyme uses fatty acyl thioesters of ACP in vivo. Different forms of the enzyme may have preferences for substrates with different chain length. For example, the activity of FabZ, the ubiquitous enzyme in bacteria, decreases with increasing chain length. Gram-negative bacteria that produce unsaturated fatty acids, such as Escherichia coli, have another form (FabA) that prefers intermediate chain length, and also catalyses EC 188.8.131.52, trans-2-decenoyl-[acyl-carrier protein] isomerase. Despite the differences both forms can catalyse all steps leading to the synthesis of palmitate (C16:0). FabZ, but not FabA, can also accept unsaturated substrates [Heath96a].
Instance reactions of [a (3R)-3-hydroxyacyl-[acyl-carrier protein] → a trans-2-enoyl-[acyl-carrier protein] + H2O] (184.108.40.206/220.127.116.11):
i1: a (3R)-3-hydroxydecanoyl-[acp] → a (2E)-dec-2-enoyl-[acp] + H2O (18.104.22.168/22.214.171.124)
i2: a (3R)-3-hydroxyhexanoyl-[acp] → a trans hex-2-enoyl-[acp] + H2O (126.96.36.199/188.8.131.52)
i3: a (3R)-3-hydroxypalmitoyl-[acp] → a trans hexadecenoyl-[acp] + H2O (184.108.40.206/220.127.116.11)
i4: (R)-3-hydroxy-cis-vacc-11-enoyl-[acp] → a (2-trans-11-cis)-vaccen-2-enoyl-[acp] + H2O (18.104.22.168)
i5: a (3R)-3-hydroxyoctanoyl-[acp] → a trans oct-2-enoyl-[acp] + H2O (22.214.171.124/126.96.36.199)
i6: a (3R)-3-hydroxymyristoyl-[acp] → a trans tetradec-2-enoyl-[acp] + H2O (188.8.131.52/184.108.40.206)
i7: a (3R)-3-hydroxybutanoyl-[acp] → a crotonyl-[acp] + H2O (220.127.116.11/18.104.22.168)
i8: a (3R)-3-hydroxydodecanoyl-[acp] → a (2E)-dodec-2-enoyl-[acp] + H2O (22.214.171.124/126.96.36.199)
Heath96a: Heath RJ, Rock CO (1996). "Roles of the FabA and FabZ beta-hydroxyacyl-acyl carrier protein dehydratases in Escherichia coli fatty acid biosynthesis." J Biol Chem 1996;271(44);27795-801. PMID: 8910376
Mizugaki68: Mizugaki M, Swindell AC, Wakil SJ (1968). "Intermediate- and long-chain beta-hydroxyacyl-ACP dehydrases from E. coli fatty acid synthetase." Biochem Biophys Res Commun 33(3);520-7. PMID: 4881058
Mohan94: Mohan S, Kelly TM, Eveland SS, Raetz CR, Anderson MS (1994). "An Escherichia coli gene (FabZ) encoding (3R)-hydroxymyristoyl acyl carrier protein dehydrase. Relation to fabA and suppression of mutations in lipid A biosynthesis." J Biol Chem 1994;269(52);32896-903. PMID: 7806516
Sharma90: Sharma A, Henderson BS, Schwab JM, Smith JL (1990). "Crystallization and preliminary X-ray analysis of beta-hydroxydecanoyl thiol ester dehydrase from Escherichia coli." J Biol Chem 1990;265(9);5110-2. PMID: 2180957
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