1dkw
From Proteopedia
CRYSTAL STRUCTURE OF TRIOSE-PHOSPHATE ISOMERASE WITH MODIFIED SUBSTRATE BINDING SITE
Overview
Loop 8 (residues 232-242) in triosephosphate isomerase (TIM) is a highly conserved loop that forms a tight binding pocket for the phosphate moiety of the substrate. Its sequence includes the fully conserved, solvent-exposed Leu238. The tight phosphate-binding pocket explains the high substrate specificity of TIM being limited to the in vivo substrates dihydroxyacetone-phosphate and D-glyceraldehyde-3-phosphate. Here we use the monomeric variant of trypanosomal TIM for exploring the structural consequences of shortening this loop. The mutagenesis, guided by extensive modeling calculations and followed up by crystallographic characterization, is aimed at widening the phosphate-binding pocket and, consequently, changing the substrate specificity. Two new variants were characterized. The crystal structures of these variants indicate that in monomeric forms of TIM, the Leu238 side-chain is nicely buried in a hydrophobic cluster. Monomeric forms of wild-type dimeric TIM are known to exist transiently as folding intermediates; our structural analysis suggests that in this monomeric form, Leu238 of loop 8 also adopts this completely buried conformation, which explains its full conservation across the evolution. The much wider phosphate-binding pocket of the new variant allows for the development of a new TIM variant with a different substrate specificity.
About this Structure
1DKW is a Single protein structure of sequence from Trypanosoma brucei brucei. Full crystallographic information is available from OCA.
Reference
Modeling, mutagenesis, and structural studies on the fully conserved phosphate-binding loop (loop 8) of triosephosphate isomerase: toward a new substrate specificity., Norledge BV, Lambeir AM, Abagyan RA, Rottmann A, Fernandez AM, Filimonov VV, Peter MG, Wierenga RK, Proteins. 2001 Feb 15;42(3):383-9. PMID:11151009 Page seeded by OCA on Fri May 2 13:58:04 2008
