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

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

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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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.

Original languageEnglish
Article number112224
JournalColloids and Surfaces B: Biointerfaces
StateAccepted/In press - 2021


  • Pyridoxal phosphate
  • Sphingolipids
  • Sphingosine
  • Vitroprocine
  • α-oxoamine synthases, acyl-CoA transferase


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