Properties of bacterial and archaeal branched-chain amino acid aminotransferases
- Authors: Bezsudnova E.Y.1, Boyko K.M.1,2, Popov V.O.1,2
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Affiliations:
- Bach Institute of Biochemistry, The Federal Research Centre “Fundamentals of Biotechnology”
- National Research Center “Kurchatov Institute”
- Issue: Vol 82, No 13 (2017)
- Pages: 1572-1591
- Section: Review
- URL: https://journals.rcsi.science/0006-2979/article/view/151548
- DOI: https://doi.org/10.1134/S0006297917130028
- ID: 151548
Cite item
Abstract
Branched-chain amino acid aminotransferases (BCATs) catalyze reversible stereoselective transamination of branched-chain amino acids (BCAAs) L-leucine, L-isoleucine, and L-valine. BCATs are the key enzymes of BCAA metab- olism in all organisms. The catalysis proceeds through the ping-pong mechanism with the assistance of the cofactor pyri- doxal 5′-phosphate (PLP). BCATs differ from other (S)-selective transaminases (TAs) in 3D-structure and organization of the PLP-binding domain. Unlike other (S)-selective TAs, BCATs belong to the PLP fold type IV and are characterized by the proton transfer on the re-face of PLP, in contrast to the si-specificity of proton transfer in fold type I (S)-selective TAs. Moreover, BCATs are the only (S)-selective enzymes within fold type IV TAs. Dual substrate recognition in BCATs is imple- mented via the “lock and key” mechanism without side-chain rearrangements of the active site residues. Another feature of the active site organization in BCATs is the binding of the substrate α-COOH group on the P-side of the active site near the PLP phosphate group. Close localization of two charged groups seems to increase the effectiveness of external aldimine for- mation in BCAT catalysis. In this review, the structure-function features and the substrate specificity of bacterial and archaeal BCATs are analyzed. These BCATs differ from eukaryotic ones in the wide substrate specificity, optimal tempera- ture, and reactivity toward pyruvate as the second substrate. The prospects of biotechnological application of BCATs in stereoselective synthesis are discussed.
About the authors
E. Yu. Bezsudnova
Bach Institute of Biochemistry, The Federal Research Centre “Fundamentals of Biotechnology”
Author for correspondence.
Email: eubez@inbi.ras.ru
Russian Federation, Moscow, 119071
K. M. Boyko
Bach Institute of Biochemistry, The Federal Research Centre “Fundamentals of Biotechnology”; National Research Center “Kurchatov Institute”
Email: eubez@inbi.ras.ru
Russian Federation, Moscow, 119071; Moscow, 123098
V. O. Popov
Bach Institute of Biochemistry, The Federal Research Centre “Fundamentals of Biotechnology”; National Research Center “Kurchatov Institute”
Email: eubez@inbi.ras.ru
Russian Federation, Moscow, 119071; Moscow, 123098
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