4o93

Publication Abstract from PubMed

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.

Structural biology. Division of labor in transhydrogenase by alternating proton translocation and hydride transfer.,Leung JH, Schurig-Briccio LA, Yamaguchi M, Moeller A, Speir JA, Gennis RB, Stout CD Science. 2015 Jan 9;347(6218):178-81. doi: 10.1126/science.1260451. PMID:25574024^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.