2fli

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{{STRUCTURE_2fli| PDB=2fli | SCENE= }}
{{STRUCTURE_2fli| PDB=2fli | SCENE= }}
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'''The crystal structure of D-ribulose 5-phosphate 3-epimerase from Streptococus pyogenes complexed with D-xylitol 5-phosphate'''
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===The crystal structure of D-ribulose 5-phosphate 3-epimerase from Streptococus pyogenes complexed with D-xylitol 5-phosphate===
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==Overview==
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The "ribulose phosphate binding" superfamily defined by the Structural Classification of Proteins (SCOP) database is considered the result of divergent evolution from a common (beta/alpha)(8)-barrel ancestor. The superfamily includes d-ribulose 5-phosphate 3-epimerase (RPE), orotidine 5'-monophosphate decarboxylase (OMPDC), and 3-keto-l-gulonate 6-phosphate decarboxylase (KGPDC), members of the OMPDC suprafamily, as well as enzymes involved in histidine and tryptophan biosynthesis that utilize phosphorylated metabolites as substrates. We now report studies of the functional and structural relationships of RPE to the members of the superfamily. As suggested by the results of crystallographic studies of the RPEs from rice [Jelakovic, S., Kopriva, S., Suss, K. H., and Schulz, G. E. (2003) J. Mol. Biol. 326, 127-35] and Plasmodium falciparum [Caruthers, J., Bosch, J., Bucker, F., Van Voorhis, W., Myler, P., Worthey, E., Mehlin, C., Boni, E., De Titta, G., Luft, J., Kalyuzhniy, O., Anderson, L., Zucker, F., Soltis, M., and Hol, W. G. J. (2006) Proteins 62, 338-42], the RPE from Streptococcus pyogenes is activated by Zn(2+) which binds with a stoichiometry of one ion per polypeptide. Although wild type RPE has a high affinity for Zn(2+) and inactive apoenzyme cannot be prepared, the affinity for Zn(2+) is decreased by alanine substitutions for the two histidine residues that coordinate the Zn(2+) ion (H34A and H67A); these mutant proteins can be prepared in an inactive, metal-free form and activated by exogenous Zn(2+). The crystal structure of the RPE was solved at 1.8 A resolution in the presence of d-xylitol 5-phosphate, an inert analogue of the d-xylulose 5-phosphate substrate. This structure suggests that the 2,3-enediolate intermediate in the 1,1-proton transfer reaction is stabilized by bidentate coordination to the Zn(2+) that also is liganded to His 34, Asp 36, His 67, and Asp 176; the carboxylate groups of the Asp residues are positioned also to function as the acid/base catalysts. Although the conformation of the bound analogue resembles those of ligands bound in the active sites of OMPDC and KGPDC, the identities of the active site residues that coordinate the essential Zn(2+) and participate as acid/base catalysts are not conserved. We conclude that only the phosphate binding motif located at the ends of the seventh and eighth beta-strands of the (beta/alpha)(8)-barrel is functionally conserved among RPE, OMPDC, and KGPDC, consistent with the hypothesis that the members of the "ribulose phosphate binding" (beta/alpha)(8)-barrel "superfamily" as defined by SCOP have not evolved by evolutionary processes involving the intact (beta/alpha)(8)-barrel. Instead, this "superfamily" may result from assembly from smaller modules, including the conserved phosphate binding motif associated with the C-terminal (beta/alpha)(2)-quarter barrel.
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(as it appears on PubMed at http://www.pubmed.gov), where 16489742 is the PubMed ID number.
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{{ABSTRACT_PUBMED_16489742}}
==About this Structure==
==About this Structure==
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[[Category: Gerlt, J A.]]
[[Category: Gerlt, J A.]]
[[Category: D-xylitol 5-phosphate]]
[[Category: D-xylitol 5-phosphate]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 04:02:09 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 17:30:59 2008''

Revision as of 14:31, 28 July 2008

Image:2fli.png

Template:STRUCTURE 2fli

The crystal structure of D-ribulose 5-phosphate 3-epimerase from Streptococus pyogenes complexed with D-xylitol 5-phosphate

Template:ABSTRACT PUBMED 16489742

About this Structure

2FLI is a Single protein structure of sequence from Streptococcus pyogenes. Full crystallographic information is available from OCA.

Reference

D-Ribulose 5-phosphate 3-epimerase: functional and structural relationships to members of the ribulose-phosphate binding (beta/alpha)8-barrel superfamily., Akana J, Fedorov AA, Fedorov E, Novak WR, Babbitt PC, Almo SC, Gerlt JA, Biochemistry. 2006 Feb 28;45(8):2493-503. PMID:16489742

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