Tyrosine metabolism: identification of a key residue in the acquisition of prephenate aminotransferase activity by 1β aspartate aminotransferase

Cécile Giustini (1) , Matthieu Graindorge (1) , David Cobessi (2) , Serge Crouzy (3) , Adeline Robin (1) , Gilles Curien (1) , Michel Matringe (1)

1 LPCV - Physiologie cellulaire et végétale
2 IBS - UMR 5075 - Institut de biologie structurale
3 MCT - Groupe modélisation et chimie théorique

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, that is, 1β aspartate aminotransferase (1β AAT), N-succinyl-l,l-diaminopimelate aminotransferase, and branched-chain aminotransferase. The present work aimed at identifying molecular determinant(s) of 1β AAT prephenate aminotransferase (PAT) activity. To that purpose, we conducted X-ray crystal structure analysis of two PAT competent 1β AAT from Arabidopsis thaliana and Rhizobium meliloti and one PAT incompetent 1β AAT from R. meliloti. This structural analysis supported by site-directed mutagenesis, modeling, and molecular dynamics simulations allowed us to identify a molecular determinant of PAT activity in the flexible N-terminal loop of 1β AAT. Our data reveal that a Lys/Arg/Gln residue in position 12 in the sequence (numbering according to Thermus thermophilus 1β 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 1β AAT.

Mots clés: tyrosine metabolism; structure function; 1β aspartate/prephenate aminotransferase; arogenate route; molecular modeling; prephenate; 1 aspartate aminotransferase; molecular modeling Abreviation: AAT Aspartate aminotransferase; PAT Prephenate aminotransferase

Domaines: Biochimie [q-bio.BM]; Biologie structurale [q-bio.BM]; Biologie végétale; Modélisation et simulation

Cécile Giustini, Matthieu Graindorge, David Cobessi, Serge Crouzy, Adeline Robin, et al.. Tyrosine metabolism: identification of a key residue in the acquisition of prephenate aminotransferase activity by 1β aspartate aminotransferase. FEBS Journal, 2019, 286 (11), pp.2118-2134. ⟨10.1111/febs.14789⟩. ⟨hal-02093098⟩