Structural insights into the substrate selectivity of α-oxoamine synthases from marine Vibrio sp. QWI-06.

Pyridoxal phosphate (PLP)-dependent α-oxoamine synthases are generally believed to be responsible for offloading and elongating polyketides or catalyzing the condensation of amino acids and acyl-CoA thioester substrates, such as serine into sphingolipids and cysteate into sulfonolipids. Previously, we discovered vitroprocines, which are tyrosine- and phenylalanine-polyketide derivatives, as potential new antibiotics from the genus Vibrio. Using bioinformatics analysis, we identified putative genes of PLP-dependent enzyme from marine Vibrio sp. QWI-06, implying a capability to produce amino-polyketide derivatives. One of these genes was cloned, and the recombinant protein, termed Vibrio sp. QWI-06 α-oxoamine synthases-1 (VsAOS1), was overexpressed for structural and biochemical characterization. The crystal structure of the dimeric VsAOS1 was determined at 1.8-Å resolution in the presence of L-glycine. The electron density map indicated a glycine molecule occupying the pyridoxal binding site in one monomer, suggesting a snapshot of the initiation process upon the loading of amino acid substrate. In mass spectrometry analysis, VsAOS1 strictly acted to condense L-glycine with C12 or C16 acyl-CoA, including unsaturated acyl analog. Furthermore, a single residue replacement of VsAOS1 (G243S) allowed the enzyme to generate sphingoid derivative when L-serine and lauroyl-CoA were used as substrates. Our data elucidate the mechanism of substrate binding and selectivity by the VsAOS1 and provide a thorough understanding of the molecular basis for the amino acid preference of AOS members. Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.

Citation

Hsin-Yang Chang, Li-Hua Lo, Yu-Hsuan Lan, Mao-Xuan Hong, Yuen Ting Chan, Tzu-Ping Ko, Yu-Ru Huang, Tien-Hsing Cheng, Chih-Chuang Liaw. Structural insights into the substrate selectivity of α-oxoamine synthases from marine Vibrio sp. QWI-06. Colloids and surfaces. B, Biointerfaces. 2022 Feb;210:112224

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PMID: 34838420

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