L-allo-threonine aldolase with an H128Y/S292R mutation from Aeromonas jandaei DK-39 reveals the structural basis of changes in substrate stereoselectivity.
Acta Crystallogr D Biol Crystallogr
; 70(Pt 6): 1695-703, 2014 Jun.
Article
in En
| MEDLINE
| ID: mdl-24914980
ABSTRACT
L-allo-Threonine aldolase (LATA), a pyridoxal-5'-phosphate-dependent enzyme from Aeromonas jandaei DK-39, stereospecifically catalyzes the reversible interconversion of L-allo-threonine to glycine and acetaldehyde. Here, the crystal structures of LATA and its mutant LATA_H128Y/S292R were determined at 2.59 and 2.50â
Å resolution, respectively. Their structures implied that conformational changes in the loop consisting of residues Ala123-Pro131, where His128 moved 4.2â
Å outwards from the active site on mutation to a tyrosine residue, regulate the substrate specificity for L-allo-threonine versus L-threonine. Saturation mutagenesis of His128 led to diverse stereoselectivity towards L-allo-threonine and L-threonine. Moreover, the H128Y mutant showed the highest activity towards the two substrates, with an 8.4-fold increase towards L-threonine and a 2.0-fold increase towards L-allo-threonine compared with the wild-type enzyme. The crystal structures of LATA and its mutant LATA_H128Y/S292R reported here will provide further insights into the regulation of the stereoselectivity of threonine aldolases targeted for the catalysis of L-allo-threonine/L-threonine synthesis.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Glycine Hydroxymethyltransferase
/
Aeromonas
/
Mutation
Language:
En
Journal:
Acta Crystallogr D Biol Crystallogr
Year:
2014
Document type:
Article
Affiliation country: