Acyl transferase domain in polyketide synthase (PKS) enzymes [Secondary metabolites biosynthesis, transport and catabolism].

polyketide synthases (PKSs) polymerize simple fatty acids into a large variety of different products, called polyketides, by successive decarboxylating Claisen condensations. PKSs can be divided into 2 groups, modular type I PKSs consisting of one or more large multifunctional proteins and iterative type II PKSs, complexes of several monofunctional subunits.

Beta-ketoacyl synthase. The structure of beta-ketoacyl synthase is similar to that of the thiolase family and also chalcone synthase. The active site of beta-ketoacyl synthase is located between the N and C-terminal domains.

LCL-type Condensation (C) domain of non-ribosomal peptide synthetases(NRPSs) and similar domains including the C-domain of SgcC5, a free-standing NRPS with both ester- and amide- bond forming activity. LCL-type Condensation (C) domains catalyze peptide bond formation between two L-amino acids, ((L)C(L)). C-domains of NRPSs catalyze peptide bond formation within (usually) large multi-modular enzymatic complexes. NRPS can use a large variety of acyl monomers (approximately 500 different possible monomer substrates as opposed to the 20 standard amino acids in ribosomal protein synthesis) to construct bioactive secondary metabolites of 2 to 18 units long (with various activities such as antibiotic, antifungal, antitumor and immunosuppression). In addition to the LCL-type, there are various subtypes of C-domains such as the DCL-type which links an L-amino acid to the D-amino acid at the end of a growing peptide, starter C-domains which acylate the first amino acid with a beta-hydroxy carboxylic acid, and heterocyclization (Cyc) domains which catalyze both peptide bond formation and cyclization of Cys, Ser, or Thr residues. Typically, an NRPS module consists of an adenylation domain, a peptidyl carrier protein (PCP) domain (also known as thiolation (T) domain) and a C-domain. NRPS modules may also include specialized domains such as the terminal-module thioesterase (Te) domain that releases the product via hydrolysis or macrocyclization and any of various C-domain family members such as the epimerization (E) domain, the ester-bond forming C-domain, dual E/C (epimerization and condensation) domains, and the X-domain. Streptomyces globisporus SgcC5 is a free-standing NRPS condensation enzyme (rather than a modular NRPS), which catalyzes the condensation between the SgcC2-tethered (S)-3-chloro-5-hydroxy-beta-tyrosine and (R)-1phenyl-1,2-ethanediol, forming an ester bond, during the synthesis of the chromoprotein enediyne antitumor antibiotic C-1027. It has some acceptor substrate promiscuity as it has been shown to also catalyze the formation of an amide bond between SgcC2-tethered (S)-3-chloro-5-hydroxy-beta-tyrosine and a mimic of the enediyne core acceptor substrate having an amine at its C-2 position. C-domains typically have a conserved HHxxxD motif at the active site; mutations in this motif can abolish or diminish condensation activity. An HHxx[SAG]DGxSx(6)[ED] motif is characteristic of LCL-type C-domains.

Acyl transferase domain in polyketide synthase (PKS) enzymes.

ChainA, CurL [Moorena producens 3L],4MZ0_B Chain B, CurL [Moorena producens 3L]

Streptomcyesalbus JA3453 oxazolomycin ketosynthase domain OzmN KS2 [Streptomyces albus],4WKY_B Streptomcyes albus JA3453 oxazolomycin ketosynthase domain OzmN KS2 [Streptomyces albus]

Streptomcyesalbus JA3453 oxazolomycin ketosynthase domain OzmQ KS1 [Streptomyces albus]

ChainA, Polyketide synthase [Streptomyces graminofaciens],7VEF_A Chain A, Polyketide synthase [Streptomyces graminofaciens]

ChainA, EryAI [Saccharopolyspora erythraea],7M7J_B Chain B, EryAI [Saccharopolyspora erythraea]

Phenolphthiocerol/phthiocerol polyketide synthase subunit E OS=Mycobacterium bovis (strain ATCC BAA-935 / AF2122/97) OX=233413 GN=ppsE PE=1 SV=1

Phenolphthiocerol/phthiocerol polyketide synthase subunit E OS=Mycobacterium tuberculosis (strain ATCC 25618 / H37Rv) OX=83332 GN=ppsE PE=1 SV=1

Phenolphthiocerol/phthiocerol polyketide synthase subunit E OS=Mycobacterium tuberculosis (strain CDC 1551 / Oshkosh) OX=83331 GN=ppsE PE=3 SV=1

Mycoketide-CoA synthase OS=Mycobacterium tuberculosis (strain ATCC 25618 / H37Rv) OX=83332 GN=pks12 PE=1 SV=1

Phenolphthiocerol synthesis polyketide synthase type I Pks15/1 OS=Mycobacterium marinum (strain ATCC BAA-535 / M) OX=216594 GN=pks15/1 PE=1 SV=1