2X30

Crystal structure of the r139n mutant of a bifunctional enzyme pria

Summary for 2X30

• Entry DOI: 10.2210/pdb2x30/pdb
• Related: 1VZW 2VEP
• Descriptor: PHOSPHORIBOSYL ISOMERASE A, SULFATE ION (3 entities in total)
• Functional Keywords: aromatic amino acid biosynthesis, tryptophan biosynthesis, conformational diversity, dual-substrate specificity, histidine biosynthesis, isomerase, loops motion, hisa, trpf
• Biological source: STREPTOMYCES COELICOLOR
• Cellular location: Cytoplasm : P16250
• Total number of polymer chains: 1
• Total formula weight: 25255.28

Authors

Noda-Garcia, L.,Camacho-Zarco, A.R.,Verdel-Aranda, K.,Wright, H.,Soberon, X.,Fulop, V.,Barona-Gomez, F. (deposition date: 2010-01-20, release date: 2010-02-02, Last modification date: 2023-12-20)

Primary citation

Noda-Garcia, L.,Camacho-Zarco, A.R.,Verdel-Aranda, K.,Wright, H.,Soberon, X.,Fulop, V.,Barona-Gomez, F.
Identification and Analysis of Residues Contained on Beta --> Alpha Loops of the Dual-Substrate (Betaalpha)(8) Phosphoribosyl Isomerase a (Pria) Specific for its Phosphoribosyl Anthranilate Isomerase Activity.
Protein Sci., 19:535-, 2010

PubMed Abstract: A good model to experimentally explore evolutionary hypothesis related to enzyme function is the ancient-like dual-substrate (beta alpha)(8) phosphoribosyl isomerase A (PriA), which takes part in both histidine and tryptophan biosynthesis in Streptomyces coelicolor and related organisms. In this study, we determined the Michaelis-Menten enzyme kinetics for both isomerase activities in wild-type PriA from S. coelicolor and in selected single-residue monofunctional mutants, identified after Escherichia coli in vivo complementation experiments. Structural and functional analyses of a hitherto unnoticed residue contained on the functionally important beta --> alpha loop 5, namely, Arg(139), which was postulated on structural grounds to be important for the dual-substrate specificity of PriA, is presented for the first time. Indeed, enzyme kinetics analyses done on the mutant variants PriA_Ser(81)Thr and PriA_Arg(139)Asn showed that these residues, which are contained on beta --> alpha loops and in close proximity to the N-terminal phosphate-binding site, are essential solely for the phosphoribosyl anthranilate isomerase activity of PriA. Moreover, analysis of the X-ray crystallographic structure of PriA_Arg(139)Asn elucidated at 1.95 A herein strongly implicates the occurrence of conformational changes in this beta --> alpha loop as a major structural feature related to the evolution of the dual-substrate specificity of PriA. It is suggested that PriA has evolved by tuning a fine energetic balance that allows the sufficient degree of structural flexibility needed for accommodating two topologically dissimilar substrates--within a bifunctional and thus highly constrained active site--without compromising its structural stability.

PubMed: 20066665
DOI: 10.1002/PRO.331

Experimental method

X-RAY DIFFRACTION (1.95 Å)