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CATH Superfamily 3.10.129.110

Polyketide synthase dehydratase

The name of this superfamily has been modified since the most recent official CATH+ release (v4_4_0). At the point of the last release, this superfamily was named:

"
Polyketide synthase dehydratase
".

Functional Families

Overview of the Structural Clusters (SC) and Functional Families within this CATH Superfamily. Clusters with a representative structure are represented by a filled circle.
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FunFam 2: Fatty acid synthase

There are 8 EC terms in this cluster

Please note: EC annotations are assigned to the full protein sequence rather than individual protein domains. Since a given protein can contain multiple domains, it is possible that some of the annotations below come from additional domains that occur in the same protein, but have been classified elsewhere in CATH.

Note: The search results have been sorted with the annotations that are found most frequently at the top of the list. The results can be filtered by typing text into the search box at the top of the table.

EC Term Annotations Evidence
3-oxoacyl-[acyl-carrier-protein] reductase. [EC: 1.1.1.100]
(3R)-3-hydroxyacyl-[acyl-carrier-protein] + NADP(+) = 3-oxoacyl-[acyl- carrier-protein] + NADPH.
  • Exhibits a marked preference for [acyl-carrier-protein] derivatives over CoA derivatives as substrates.
 5 P12276 P12785 P19096 P49327 Q71SP7
Beta-ketoacyl-[acyl-carrier-protein] synthase I. [EC: 2.3.1.41]
Acyl-[acyl-carrier-protein] + malonyl-[acyl-carrier-protein] = 3-oxoacyl- [acyl-carrier-protein] + CO(2) + [acyl-carrier-protein].
  • Responsible for the chain-elongation step of dissociated (type II) fatty-acid biosynthesis, i.e. the addition of two C atoms to the fatty-acid chain.
  • Escherichia coli mutants that lack this enzyme are deficient in unsaturated fatty acids.
  • Can use fatty acyl thioesters of ACP (C(2) to C(16)) as substrates, as well as fatty acyl thioesters of Co-A (C(4) to C(16)).
  • The substrate specificity is very similar to that of EC 2.3.1.179 with the exception that the latter enzyme is far more active with palmitoleoyl-ACP (C(16)-Delta(9)) as substrate, allowing the organism to regulate its fatty-acid composition with changes in temperature.
 5 P12276 P12785 P19096 P49327 Q71SP7
Oleoyl-[acyl-carrier-protein] hydrolase. [EC: 3.1.2.14]
Oleoyl-[acyl-carrier-protein] + H(2)O = [acyl-carrier-protein] + oleate.
  • Acts on [acyl-carrier-protein] thioesters of fatty acids from C(12) to C(18), but the derivative of oleic acid is hydrolyzed much more rapidly than any other compound tested.
 5 P12276 P12785 P19096 P49327 Q71SP7
Fatty-acid synthase system. [EC: 2.3.1.85]
Acetyl-CoA + n malonyl-CoA + 2n NADPH = a long-chain fatty acid + (n+1) CoA + n CO(2) + 2n NADP(+).
  • The animal enzyme is a multifunctional protein catalyzing the reactions of EC 2.3.1.38, EC 2.3.1.39, EC 2.3.1.41, EC 1.1.1.100, EC 4.2.1.59, EC 1.3.1.39 and EC 3.1.2.14.
  • Cf. EC 2.3.1.86.
 5 P12276 P12785 P19096 P49327 Q71SP7
Enoyl-[acyl-carrier-protein] reductase (NADPH, Re-specific). [EC: 1.3.1.39]
An acyl-[acyl-carrier protein] + NADP(+) = a trans-2,3-dehydroacyl-[acyl- carrier protein] + NADPH.
  • This enzyme completes each cycle of fatty acid elongation by catalyzing the stereospecific reduction of the double bond at position 2 of a growing fatty acid chain, while linked to an acyl- carrier protein.
  • It is one of the activities of EC 2.3.1.85.
  • The mammalian enzyme is Re-specific with respect to NADP(+) (cf. EC 1.3.1.10 and and EC 1.3.1.104).
 5 P12276 P12785 P19096 P49327 Q71SP7
3-hydroxyacyl-[acyl-carrier-protein] dehydratase. [EC: 4.2.1.59]
A (3R)-3-hydroxyacyl-[acyl-carrier protein] = a trans-2-enoyl-[acyl- carrier protein] + H(2)O.
  • 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 catalyzes EC 5.3.3.14.
  • Despite the differences both forms can catalyze all steps leading to the synthesis of palmitate (C16:0).
  • FabZ, but not FabA, can also accept unsaturated substrates.
  • Formerly EC 4.2.1.58, EC 4.2.1.60 and EC 4.2.1.61.
 5 P12276 P12785 P19096 P49327 Q71SP7
[Acyl-carrier-protein] S-acetyltransferase. [EC: 2.3.1.38]
Acetyl-CoA + [acyl-carrier-protein] = CoA + acetyl-[acyl-carrier- protein].
  • Essential, along with EC 2.3.1.39, for the initiation of fatty-acid biosynthesis in bacteria.
  • The substrate acetyl-CoA protects the enzyme against inhibition by N-ethylmaleimide or iodoacetamide.
  • This is one of the activities associated with EC 2.3.1.180.
 5 P12276 P12785 P19096 P49327 Q71SP7
[Acyl-carrier-protein] S-malonyltransferase. [EC: 2.3.1.39]
Malonyl-CoA + an [acyl-carrier-protein] = CoA + a malonyl-[acyl-carrier- protein].
  • Essential, along with EC 2.3.1.38, for the initiation of fatty-acid biosynthesis in bacteria.
  • Also provides the malonyl groups for polyketide biosynthesis.
  • The product of the reaction, malonyl-ACP, is an elongation substrate in fatty-acid biosynthesis.
  • In Mycobacterium tuberculosis, holo-ACP (the product of EC 2.7.8.7) is the preferred substrate.
  • This enzyme also forms part of the multienzyme complexes EC 4.1.1.88 and EC 4.1.1.89.
  • Malonylation of ACP is immediately followed by decarboxylation within the malonate-decarboxylase complex to yield acetyl-ACP, the catalytically active species of the decarboxylase.
  • In the enzyme from Klebsiella pneumoniae, methylmalonyl-CoA can also act as a substrate but acetyl-CoA cannot whereas the enzyme from Pseudomonas putida can use both as substrates.
  • The ACP subunit found in fatty-acid biosynthesis contains a pantetheine-4'-phosphate prosthetic group; that from malonate decarboxylase also contains pantetheine-4'-phosphate but in the form of a 2'-(5-triphosphoribosyl)-3'-dephospho-CoA prosthetic group.
 5 P12276 P12785 P19096 P49327 Q71SP7
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