Snapshots along the catalytic path of KabA, a PLP-dependent aminotransferase required for kanosamine biosynthesis in Bacillus cereus UW85.Prasertanan, T., Palmer, D.R.J., Sanders, D.A.R.
(2021) J Struct Biol 213: 107744-107744
- PubMed: 33984505
- DOI: 10.1016/j.jsb.2021.107744
- Primary Citation of Related Structures:
7KZ3, 7KZ5, 7KZ6, 7KZD
- PubMed Abstract:
Kanosamine is an antibiotic and antifungal monosaccharide. The kanosamine biosynthetic pathway from glucose 6-phosphate in Bacillus cereus UW85 was recently reported, and the functions of each of the three enzymes in the pathway, KabA, KabB and KabC, were demonstrated ...
Kanosamine is an antibiotic and antifungal monosaccharide. The kanosamine biosynthetic pathway from glucose 6-phosphate in Bacillus cereus UW85 was recently reported, and the functions of each of the three enzymes in the pathway, KabA, KabB and KabC, were demonstrated. KabA, a member of a subclass of the VI β family of PLP-dependent aminotransferases, catalyzes the second step in the pathway, generating kanosamine 6-phosphate (K6P) using l-glutamate as the amino-donor. KabA catalysis was shown to be extremely efficient, with a second-order rate constant with respect to K6P transamination of over 10 7 M -1 s -1 . Here we report the high-resolution structure of KabA in both the PLP- and PMP-bound forms. In addition, co-crystallization with K6P allowed the structure of KabA in complex with the covalent PLP-K6P adduct to be solved. Co-crystallization or soaking with glutamate or 2-oxoglutarate did not result in crystals with either substrate/product. Reduction of the PLP-KabA complex with sodium cyanoborohydride gave an inactivated enzyme, and crystals of the reduced KabA were soaked with the l-glutamate analog glutarate to mimic the KabA-PLP-l-glutamate complex. Together these four structures give a complete picture of how the active site of KabA recognizes substrates for each half-reaction. The KabA structure is discussed in the context of homologous aminotransferases.
Department of Chemistry, University of Saskatchewan, Saskatoon, SK S7N 5C9, Canada. Electronic address: firstname.lastname@example.org.