The structure/function relationship of a dual-substrate (betaalpha)8-isomerase.
Two structures of phosphoribosyl isomerase A (PriA) from Streptomyces coelicolor, involved in both histidine and tryptophan biosynthesis, were solved at 1.8A resolution. A closed conformer was obtained, which represents the first complete structure of PriA, revealing hitherto unnoticed molecular interactions and the occurrence of conformational changes. Inspection of these conformers, including ligand-docking simulations, allowed identification of residues involved in substrate recognition, chemical catalysis and conformational changes. These predictions were validated by mutagenesis and functional analysis. Arg19 and Ser81 were shown to play critical roles within the carboxyl and amino phosphate-binding sites, respectively; the catalytic residues Asp11 and Asp130 are responsible for both activities; and Thr166 and Asp171, which make an unusual contact, are likely to elicit the conformational changes needed for adopting the active site architectures. This represents the first report of the structure/function relationship of this (betaalpha)8-isomerase.
Wright
Helena
H
Department of Biological Sciences, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK.
Noda-García
Lianet
L
Ochoa-Leyva
Adrián
A
Hodgson
David A
DA
Fülöp
Vilmos
V
Barona-Gómez
Francisco
F
D019747:Aldose-Ketose Isomerases / Q000737:chemistry* / Q000235:genetics; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry*; D001665:Binding Sites; D008958:Models, Molecular; D008969:Molecular Sequence Data; D048372:Streptomyces coelicolor / Q000201:enzymology; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
D001426:Bacterial Proteins; D019747:Aldose-Ketose Isomerases