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4dbv

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{{STRUCTURE_4dbv| PDB=4dbv | SCENE= }}
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'''GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE MUTANT WITH LEU 33 REPLACED BY THR, THR 34 REPLACED BY GLY, ASP 36 REPLACED BY GLY, LEU 187 REPLACED BY ALA, AND PRO 188 REPLACED BY SER COMPLEXED WITH NADP+'''
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===GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE MUTANT WITH LEU 33 REPLACED BY THR, THR 34 REPLACED BY GLY, ASP 36 REPLACED BY GLY, LEU 187 REPLACED BY ALA, AND PRO 188 REPLACED BY SER COMPLEXED WITH NADP+===
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==Overview==
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Mutations have been introduced in the cytosolic glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from Bacillus stearothermophilus in order to convert its cofactor selectivity from a specificity towards NAD into a preference for NADP. In the B-S mutant, five mutations (L33T, T34G, D35G, L187A, P188S) were selected on the basis of a sequence alignment with NADP-dependent chloroplastic GAPDHs. In the D32G-S mutant, two of the five mutations mentioned above (L187A, P188S) have been used in combination with another one designed from electrostatic considerations (D32G). Both mutants exhibit a dual-cofactor selectivity at the advantage of either NAD (B-S) or NADP (D32G-S). In order to analyse the cofactor-binding site plasticity at the molecular level, crystal structures of these mutants have been solved, when complexed with either NAD+ (D32G-Sn, resolution 2.5 A, R = 13.9%; B-Sn, 2.45 A, 19.3%) or NADP+ (D32G-Sp, 2.2 A, 19.2%; B-Sp, 2.5 A, 14.4%). The four refined models are very similar to that of the wild-type GAPDH and as expected resemble more closely the holo form than the apo form. In the B-S mutant, the wild-type low affinity for NADP+ seems to be essentially retained because of repulsive electrostatic contacts between the extra 2'-phosphate and the unchanged carboxylate group of residue D32. Such an antideterminant effect is not well compensated by putative attractive interactions which had been expected to arise from the newly-introduced side-chains. In this mutant, recognition of NAD+ is slightly affected with respect to that known on the wild-type, because mutations only weakly destabilize hydrogen bonds and van der Waals contacts originally present in the natural enzyme. Thus, the B-S mutant does not mimic efficiently the chloroplastic GAPDHs, and long-range and/or second-layer effects, not easily predictable from visual inspection of three-dimensional structures, need to be taken into account for designing a true "chloroplastic-like" mutant of cytosolic GAPDH. In the case of the D32G-S mutant, the dissociation constants for NAD+ and NADP+ are practically reversed with respect to those of the wild-type. The strong alteration of the affinity for NAD+ obviously proceeds from the suppression of the two wild-type hydrogen bonds between the adenosine 2'- and 3'-hydroxyl positions and the D32 carboxylate group. As expected, the efficient recognition of NADP+ is partly promoted by the removal of intra-subunit electrostatic repulsion (D32G) and inter-subunit steric hindrance (L187A, P188S). Another interesting feature of the reshaped NADP+-binding site is provided by the local stabilization of the extra 2'-phosphate which forms a hydrogen bond with the side-chain hydroxyl group of the newly-introduced S188. When compared to the presently known natural NADP-binding clefts, this result clearly demonstrates that an absolute need for a salt-bridge involving the 2'-phosphate is not required to switch the cofactor selectivity from NAD to NADP. In fact, as it is the case in this mutant, only a moderately polar hydrogen bond can be sufficient to make the extra 2'-phosphate of NADP+ well recognized by a protein environment.
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{{ABSTRACT_PUBMED_9175858}}
==About this Structure==
==About this Structure==
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[[Category: Vitoux, B.]]
[[Category: Vitoux, B.]]
[[Category: Oxidoreductase]]
[[Category: Oxidoreductase]]
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Revision as of 10:34, 3 July 2008

Image:4dbv.png

Template:STRUCTURE 4dbv

GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE MUTANT WITH LEU 33 REPLACED BY THR, THR 34 REPLACED BY GLY, ASP 36 REPLACED BY GLY, LEU 187 REPLACED BY ALA, AND PRO 188 REPLACED BY SER COMPLEXED WITH NADP+

Template:ABSTRACT PUBMED 9175858

About this Structure

4DBV is a Single protein structure of sequence from Geobacillus stearothermophilus. Full crystallographic information is available from OCA.

Reference

A crystallographic comparison between mutated glyceraldehyde-3-phosphate dehydrogenases from Bacillus stearothermophilus complexed with either NAD+ or NADP+., Didierjean C, Rahuel-Clermont S, Vitoux B, Dideberg O, Branlant G, Aubry A, J Mol Biol. 1997 May 16;268(4):739-59. PMID:9175858

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