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Publication Abstract from PubMed

Alternative routes for the post-chorismate branch of the biosynthetic pathway leading to tyrosine exist, the 4-hydroxyphenylpyruvate or the arogenate route. The arogenate route involves the transamination of prephenate into arogenate. In a previous study, we found that, depending on the microorganisms possessing the arogenate route, three different aminotransferases evolved to perform prephenate transamination i.e. 1beta aspartate aminotransferase (1beta AAT), N-succinyl-l,l-diaminopimelate aminotransferase, and branched-chain aminotransferase. The present work aimed at identifying molecular determinant(s) of 1beta AAT prephenate aminotransferase (PAT) activity. To that purpose, we conducted X-ray crystal structure analysis of two PAT competent 1beta AAT from Arabidopsis thaliana and Rhizobium meliloti, and one PAT incompetent 1beta AAT from Rhizobium meliloti. This structural analysis supported by site directed mutagenesis, modelling and molecular dynamics simulations allowed us to identify a molecular determinant of PAT activity in the flexible N-terminal loop of 1beta AAT. Our data reveal that a Lys/Arg/Gln residue in position 12 in the sequence (numbering according to Thermus thermophilus 1beta AAT), present only in PAT competent enzymes, could interact with the 4-hydroxyl group of the prephenate substrate, and thus may have a central role in the acquisition of PAT activity by 1beta AAT. This article is protected by copyright. All rights reserved.

Tyrosine metabolism: identification of a key residue in the acquisition of prephenate aminotransferase activity by 1beta aspartate aminotransferase.,Giustini C, Graindorge M, Cobessi D, Crouzy S, Robin A, Curien G, Matringe M FEBS J. 2019 Feb 16. doi: 10.1111/febs.14789. PMID:30771275^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.