6l1n
Substrate bound BacF structure from Bacillus subtillis
Structural highlights
FunctionBACF_BACSU Part of the bacABCDEF operon responsible for the biosynthesis of the nonribosomally synthesized dipeptide antibiotic bacilysin, composed of L-alanine and L-anticapsin. Bacilysin is an irreversible inactivator of the glutaminase domain of glucosamine synthetase (PubMed:20052993). Catalyzes the reductive amination of the C2 ketone of tetrahydro-hydroxyphenylpyruvate (H4HPP), with L-Phe as an amino donor, to yield tetrahydrotyrosine (H4Tyr) diastereomer (PubMed:22765234). D-Phe is not an effective amino donor (PubMed:22765234). BacF associated to BacG converts 3E,7R- and 3Z,7R-ex-H2HPP to 2S,4R,7R- and 2S,4S,7R-H4Tyr, respectively. Given that bacilysin has the 2S,4S stereochemistry in its anticapsin moiety, it is likely that the 2S,4S-H4Tyr is the diastereomer used for the biosynthesis (PubMed:22765234).[1] [2] Publication Abstract from PubMedThe nonribosomal biosynthesis of the dipeptide antibiotic bacilysin is achieved by the concerted action of multiple enzymes in the Bacillus subtilis bac operon. BacF (YwfG), encoded by the bacF gene, is a fold type I pyridoxal 5-phosphate (PLP)-dependent stereospecific transaminase. Activity assays with L-phenylalanine and 4-hydroxyphenylpyruvic acid (4HPP), a chemical analogue of tetrahydrohydroxyphenylpyruvic acid (H4HPP), revealed stereospecific substrate preferences, a finding that was consistent with previous reports on the role of this enzyme in bacilysin synthesis. The crystal structure of this dimeric enzyme was determined in its apo form as well as in substrate-bound and product-bound conformations. Two ligand-bound structures were determined by soaking BacF crystals with substrates (L-phenylalanine and 4-hydroxyphenylpyruvate). These structures reveal multiple catalytic steps: the internal aldimine with PLP and two external aldimine conformations that show the rearrangement of the external aldimine to generate product (L-tyrosine). Together, these structural snapshots provide an insight into the catalytic mechanism of this transaminase. Structural insights into the catalytic mechanism of Bacillus subtilis BacF.,Deshmukh A, Gopal B Acta Crystallogr F Struct Biol Commun. 2020 Mar 1;76(Pt 3):145-151. doi:, 10.1107/S2053230X20001636. Epub 2020 Mar 3. PMID:32134000[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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