1PTJ: Crystal structure analysis of the DI and DIII complex of transhydrogenase with a thio-nicotinamide nucleotide analogue

Citation:
Abstract
Transhydrogenase couples the reduction of NADP+ by NADH to inward proton translocation across mitochondrial and bacterial membranes. The coupling reactions occur within the protein by long distance conformational changes. In intact transhydrogenase and in complexes formed from the isolated, nucleotide-binding components, thio-NADP(H) is a good analogue for NADP(H), but thio-NAD(H) is a poor analogue for NAD(H). Crystal structures of the nucleotide-binding components show that the twists of the 3-carbothiamide groups of thio-NADP+ and of thio-NAD+ (relative to the planes of the pyridine rings), which are defined by the dihedral, Xam, are altered relative to the twists of the 3-carboxamide groups of the physiological nucleotides. The finding that thio-NADP+ is a good substrate despite an increased Xam value shows that approach of the NADH prior to hydride transfer is not obstructed by the S atom in the analogue. That thio-NAD(H) is a poor substrate appears to be the result of failure in the conformational change that establishes the ground state for hydride transfer. This might be a consequence of restricted rotation of the 3-carbothiamide group during the conformational change.
PDB ID: 1PTJDownload
MMDB ID: 24790
PDB Deposition Date: 2003/6/23
Updated in MMDB: 2012/11
Experimental Method:
x-ray diffraction
Resolution: 2.61  Å
Source Organism:
Similar Structures:
Biological Unit for 1PTJ: trimeric; determined by author and by software (PISA)
Molecular Components in 1PTJ
Label Count Molecule
Proteins (3 molecules)
2
Nad(p) Transhydrogenase Subunit Alpha Part 1
Molecule annotation
1
Nad(p) Transhydrogenase Subunit Beta
Molecule annotation
Chemicals (5 molecules)
1
1
2
3
3
1
* Click molecule labels to explore molecular sequence information.

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