7KZD image
Entry Detail
PDB ID:
7KZD
Title:
Crystal structure of KabA from Bacillus cereus UW85 in complex with the reduced internal aldimine and with bound Glutarate
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2020-12-10
Release Date:
2021-05-26
Method Details:
Experimental Method:
Resolution:
1.90 Å
R-Value Free:
0.24
R-Value Work:
0.20
R-Value Observed:
0.20
Space Group:
P 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Aminotransferase class I/II-fold pyridoxal phosphate-dependent enzyme
Chain IDs:A, B, C, D, E, F, G, H
Chain Length:445
Number of Molecules:8
Biological Source:Bacillus cereus
Primary Citation
Snapshots along the catalytic path of KabA, a PLP-dependent aminotransferase required for kanosamine biosynthesis in Bacillus cereus UW85.
J.Struct.Biol. 213 107744 107744 (2021)
PMID: 33984505 DOI: 10.1016/j.jsb.2021.107744

Abstact

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 VIβ 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 107 M-1s-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.

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