6ad3
From Proteopedia
Structural characterization of the condensation domain from Monacolin K polyketide synthase MokA
Structural highlights
Function[MOKA_MONPI] Nonaketide synthase; part of the gene cluster that mediates the biosynthesis of monakolin K, also known as lovastatin, and which acts as a potent competitive inhibitor of HMG-CoA reductase (PubMed:18578535). Monakolin K biosynthesis is performed in two stages (PubMed:19693441). The first stage is catalyzed by the nonaketide synthase mokA, which belongs to type I polyketide synthases and catalyzes the iterative nine-step formation of the polyketide (PubMed:18578535, PubMed:19693441). This PKS stage is completed by the action of dehydrogenase mokE, which catalyzes the NADPH-dependent reduction of the unsaturated tetra-, penta- and heptaketide intermediates that arise during the mokA-mediated biosynthesis of the nonaketide chain and leads to dihydromonacolin L (PubMed:19693441). Covalently bound dihydromonacolin L is released from mokA by the mokD esterase (By similarity). Conversion of dihydromonacolin L into monacolin L and then monacolin J is subsequently performed with the participation of molecular oxygen and P450 monoogygenase mokC (PubMed:19693441). Finally, mokF performs the conversion of monacoline J to monacoline K through the addition of the side-chain diketide moiety (2R)-2-methylbutanoate produced by the diketide synthase mokB (PubMed:19693441).[UniProtKB:Q0C8M2][UniProtKB:Q9Y8A5][1] [2] Publication Abstract from PubMedThe highly reducing iterative polyketide synthases responsible for lovastatin biosynthesis contains a section homologous to condensation (CON) domain observed in nonribosomal peptide synthetases (NRPSs). In the present study, we expressed the isolated lovastatin CON domain and solved the crystal structure to 1.79A resolution. The overall structure shows similarity to canonical condensation domains of NRPSs, containing the N-terminal and C-terminal subdomains that resemble enzymes of chloramphenicol acetyltransferase family, whereas distinct structural features are observed at the active site. The acceptor entry of the substrate channel is blocked by a flexible loop, thereby preventing the loading of substrate for a new round of chain elongation. The mutation of conserved catalytic motif located at the midpoint of substrate channel agrees with the incapability of CON to catalyzed amide-bond formation. The structure helps to understand the function of CON in lovastatin biosynthesis. Crystal structure of the condensation domain from lovastatin polyketide synthase.,Wang L, Yuan M, Zheng J Synth Syst Biotechnol. 2018 Nov 21;4(1):10-15. doi: 10.1016/j.synbio.2018.11.003., eCollection 2019 Mar. PMID:30533541[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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