TY - JOUR
T1 - Identification of the βTP site in the x-ray structure of F1-ATPase as the high-affinity catalytic site
AU - Mao, Hui Z.
AU - Weber, Joachim
PY - 2007/11/20
Y1 - 2007/11/20
N2 - ATP synthase uses a unique rotary mechanism to couple ATP synthesis and hydrolysis to transmembrane proton translocation. The F1 subcomplex has three catalytic nucleotide binding sites, one on each β subunit, with widely differing affinities for MgATP or MgADP. During rotational catalysis, the sites switch their affinities. The affinity of each site is determined by the position of the central γ subunit. The site with the highest nucleotide binding affinity is catalytically active. From the available x-ray structures, it is not possible to discern the high-affinity site. Using fluorescence resonance energy transfer between tryptophan residues engineered into γ and trinitrophenyl nucleotide analogs on the catalytic sites, we were able to determine that the high-affinity site is close to the C-terminal helix of γ, but at considerable distance from its N terminus. Thus, the βTP site in the x-ray structure [Abrahams JP, Leslie AGW, Lutter R, Walker JE (1994) Nature 370:621-628] is the high-affinity site, in agreement with the prediction of Yang et al. [Yang W, Gao YQ, Cui Q, Ma J, Karplus M (2003) Proc Natl Acad Sci USA 100:874-879]. Taking into account the known direction of rotation, the findings establish the sequence of affinities through which each catalytic site cycles during MgATP hydrolysis as low → high → medium → low.
AB - ATP synthase uses a unique rotary mechanism to couple ATP synthesis and hydrolysis to transmembrane proton translocation. The F1 subcomplex has three catalytic nucleotide binding sites, one on each β subunit, with widely differing affinities for MgATP or MgADP. During rotational catalysis, the sites switch their affinities. The affinity of each site is determined by the position of the central γ subunit. The site with the highest nucleotide binding affinity is catalytically active. From the available x-ray structures, it is not possible to discern the high-affinity site. Using fluorescence resonance energy transfer between tryptophan residues engineered into γ and trinitrophenyl nucleotide analogs on the catalytic sites, we were able to determine that the high-affinity site is close to the C-terminal helix of γ, but at considerable distance from its N terminus. Thus, the βTP site in the x-ray structure [Abrahams JP, Leslie AGW, Lutter R, Walker JE (1994) Nature 370:621-628] is the high-affinity site, in agreement with the prediction of Yang et al. [Yang W, Gao YQ, Cui Q, Ma J, Karplus M (2003) Proc Natl Acad Sci USA 100:874-879]. Taking into account the known direction of rotation, the findings establish the sequence of affinities through which each catalytic site cycles during MgATP hydrolysis as low → high → medium → low.
KW - ATP synthase
KW - Catalytic mechanism
KW - Rotation
UR - http://www.scopus.com/inward/record.url?scp=36749085972&partnerID=8YFLogxK
U2 - 10.1073/pnas.0709322104
DO - 10.1073/pnas.0709322104
M3 - Article
C2 - 18003896
AN - SCOPUS:36749085972
SN - 0027-8424
VL - 104
SP - 18478
EP - 18483
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 47
ER -