In:
Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 113, No. 21 ( 2016-05-24)
Kurzfassung:
Despite extensive studies, the structural basis for the mechanochemical coupling in the rotary molecular motor F 1 -ATPase (F 1 ) is still incomplete. We performed single-molecule FRET measurements to monitor conformational changes in the stator ring-α 3 β 3 , while simultaneously monitoring rotations of the central shaft-γ. In the ATP waiting dwell, two of three β-subunits simultaneously adopt low FRET nonclosed forms. By contrast, in the catalytic intermediate dwell, two β-subunits are simultaneously in a high FRET closed form. These differences allow us to assign crystal structures directly to both major dwell states, thus resolving a long-standing issue and establishing a firm connection between F 1 structure and the rotation angle of the motor. Remarkably, a structure of F 1 in an ε-inhibited state is consistent with the unique FRET signature of the ATP waiting dwell, while most crystal structures capture the structure in the catalytic dwell. Principal component analysis of the available crystal structures further clarifies the five-step conformational transitions of the αβ-dimer in the ATPase cycle, highlighting the two dominant modes: the opening/closing motions of β and the loosening/tightening motions at the αβ-interface. These results provide a new view of tripartite coupling among chemical reactions, stator conformations, and rotary angles in F 1 -ATPase.
Materialart:
Online-Ressource
ISSN:
0027-8424
,
1091-6490
DOI:
10.1073/pnas.1524720113
Sprache:
Englisch
Verlag:
Proceedings of the National Academy of Sciences
Publikationsdatum:
2016
ZDB Id:
209104-5
ZDB Id:
1461794-8
SSG:
11
SSG:
12
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