Solution structure of the NADP(H)-binding component (dIII) of proton-translocating transhydrogenase from Rhodospirillum rubrum.
Transhydrogenase is a proton pump found in the membranes of bacteria and animal mitochondria. The solution structure of the expressed, 21.5 kDa, NADP(H)-binding component (dIII) of transhydrogenase from Rhodospirillum rubrum has been solved by NMR methods. This is the first description of the structure of dIII from a bacterial source. The protein adopts a Rossmann fold: an open, twisted, parallel beta-sheet, flanked by helices. However, the binding of NADP(+) to dIII is profoundly different to that seen in other Rossmann structures, in that its orientation is reversed: the adenosine moiety interacts with the first betaalphabetaalphabeta motif, and the nicotinamide with the second. Features in the structure that might be responsible for changes in nucleotide-binding affinity during catalysis, and for interaction with other components of the enzyme, are identified. The results are compared with the recently determined, high-resolution crystal structures of human and bovine dIII which also show the reversed nucleotide orientation.
Jeeves
M
M
School of Biosciences, University of Birmingham, Edgbaston, B15 2TT, UK.
Smith
K J
KJ
Quirk
P G
PG
Cotton
N P
NP
Jackson
J B
JB
D000595:Amino Acid Sequence; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009249:NADP / Q000737:chemistry; D011487:Protein Conformation; D017494:Proton Pumps / Q000737:chemistry*; D012247:Rhodospirillum rubrum / Q000201:enzymology*
D017494:Proton Pumps; D009249:NADP