4O93: Crystal Structure Of Thermus Thermophilis Transhydrogeanse Domain Ii Dimer

NADPH/NADP(+) (the reduced form of NADP(+)/nicotinamide adenine dinucleotide phosphate) homeostasis is critical for countering oxidative stress in cells. Nicotinamide nucleotide transhydrogenase (TH), a membrane enzyme present in both bacteria and mitochondria, couples the proton motive force to the generation of NADPH. We present the 2.8 A crystal structure of the transmembrane proton channel domain of TH from Thermus thermophilus and the 6.9 A crystal structure of the entire enzyme (holo-TH). The membrane domain crystallized as a symmetric dimer, with each protomer containing a putative proton channel. The holo-TH is a highly asymmetric dimer with the NADP(H)-binding domain (dIII) in two different orientations. This unusual arrangement suggests a catalytic mechanism in which the two copies of dIII alternatively function in proton translocation and hydride transfer.
PDB ID: 4O93Download
MMDB ID: 125769
PDB Deposition Date: 2013/12/31
Updated in MMDB: 2015/01
Experimental Method:
x-ray diffraction
Resolution: 2.77  Å
Source Organism:
Similar Structures:
Biological Unit for 4O93: dimeric; determined by author and by software (PISA)
Molecular Components in 4O93
Label Count Molecule
Proteins (2 molecules)
Nad(p) Transhydrogenase Subunit Alpha 2
Molecule annotation
Nad(p) Transhydrogenase Subunit Beta
Molecule annotation
Chemical (1 molecule)
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