3o24
From Proteopedia
Crystal structure of the brevianamide F prenyltransferase FtmPT1 from Aspergillus fumigatus
Structural highlights
FunctionFTMB_ASPFU Brevianamide F prenyltransferase; part of the gene cluster that mediates the biosynthesis of fumitremorgins, indole alkaloids that carry not only intriguing chemical structures, but also interesting biological and pharmacological activities (PubMed:16000710, PubMed:23649274). The biosynthesis of fumitremorgin-type alkaloids begins by condensation of the two amino acids L-tryptophan and L-proline to brevianamide F, catalyzed by the non-ribosomal peptide synthetase ftmA (PubMed:16755625). Brevianamide F is then prenylated by the prenyltransferase ftmPT1/ftmB in the presence of dimethylallyl diphosphate, resulting in the formation of tryprostatin B (PubMed:16000710, PubMed:19113967, PubMed:21105662, PubMed:23090579). FtmPT1/ftmB shows also tryptophan aminopeptidase activity with preference for linear peptides containing a tryptophanyl moiety at the N-terminus (PubMed:18635009). The three cytochrome P450 monooxygenases, ftmP450-1/ftmC, ftmP450-2/ftmE and ftmP450-3/FtmG, are responsible for the conversion of tryprostatin B to 6-hydroxytryprostatin B, tryprostatin A to fumitremorgin C and fumitremorgin C to 12,13-dihydroxyfumitremorgin C, respectively (PubMed:19226505). The putative methyltransferase ftmMT/ftmD is expected for the conversion of 6-hydroxytryprostatin B to tryprostatin A (Probable). FtmPT2/FtmH catalyzes the prenylation of 12,13-dihydroxyfumitre-morgin C in the presence of dimethylallyl diphosphate, resulting in the formation of fumitremorgin B (PubMed:18683158). Fumitremorgin B is further converted to verruculogen by ftmOx1/ftmF via the insertion of an endoperoxide bond between the two prenyl moieties (PubMed:19763315). In some fungal species, verruculogen is further converted to fumitremorgin A, but the enzymes involved in this step have not been identified yet (Probable).[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] Publication Abstract from PubMedFungal indole prenyltransferases participate in a multitude of biosynthetic pathways. Their ability to prenylate diverse substrates has attracted interest for potential use in chemoenzymatic synthesis. The fungal indole prenyltransferase FtmPT1 catalyzes the prenylation of brevianamide F in the biosynthesis of fumitremorgin-type alkaloids, which show diverse pharmacological activities and are promising candidates for the development of antitumor agents. Here, we report crystal structures of unliganded Aspergillus fumigatus FtmPT1 as well as of a ternary complex of FtmPT1 bound to brevianamide F and an analogue of its isoprenoid substrate dimethylallyl diphosphate. FtmPT1 assumes a rare alpha/beta-barrel fold, consisting of 10 circularly arranged beta-strands surrounded by alpha-helices. Catalysis is performed in a hydrophobic reaction chamber at the center of the barrel. In combination with mutagenesis experiments, our analysis of the liganded and unliganded structures provides insight into the mechanism of catalysis and the determinants of regiospecificity. Sequence conservation of key features indicates that all fungal indole prenyltransferases possess similar active site architectures. However, while the dimethylallyl diphosphate binding site is strictly conserved in these enzymes, subtle changes in the reaction chamber likely allow for the accommodation of diverse aromatic substrates for prenylation. In support of this concept, we were able to redirect the regioselectivity of FtmPT1 by a single mutation of glycine 115 to threonine. This finding provides support for a potential use of fungal indole prenyltransferases as modifiable bioreactors that can be engineered to catalyze highly specific prenyl transfer reactions. Structure-Function Analysis of an Enzymatic Prenyl Transfer Reaction Identifies a Reaction Chamber with Modifiable Specificity.,Jost M, Zocher G, Tarcz S, Matuschek M, Xie X, Li SM, Stehle T J Am Chem Soc. 2010 Nov 24. PMID:21105662[12] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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