Structure and Flexibility of the C-Ring in the Electromotor of Rotary FoF1-ATPase of Pea Chloroplasts

Autor(en): Saroussi, Shai
Schushan, Maya
Ben-Tal, Nir
Junge, Wolfgang 
Nelson, Nathan
Stichwörter: COLI ATP SYNTHASE; CRYSTAL-STRUCTURE; ELASTIC POWER TRANSMISSION; F-ATPASE; MECHANISM; Multidisciplinary Sciences; NA+-ATPASE; NORMAL-MODE ANALYSIS; PROTEIN; ROTOR RING; Science & Technology - Other Topics; VISCOELASTIC DYNAMICS
Erscheinungsdatum: 2012
Herausgeber: PUBLIC LIBRARY SCIENCE
Journal: PLOS ONE
Volumen: 7
Ausgabe: 9
Zusammenfassung: 
A ring of 8-15 identical c-subunits is essential for ion-translocation by the rotary electromotor of the ubiquitous FOF1-ATPase. Here we present the crystal structure at 3.4 angstrom resolution of the c-ring from chloroplasts of a higher plant (Pisum sativum), determined using a native preparation. The crystal structure was found to resemble that of an (ancestral) cyanobacterium. Using elastic network modeling to investigate the ring's eigen-modes, we found five dominant modes of motion that fell into three classes. They revealed the following deformations of the ring: (I) ellipsoidal, (II) opposite twisting of the luminal circular surface of the ring against the stromal surface, and (III) kinking of the hairpin-shaped monomers in the middle, resulting in bending/stretching of the ring. Extension of the elastic network analysis to rings of different cn-symmetry revealed the same classes of dominant modes as in P. sativum (c(14)). We suggest the following functional roles for these classes: The first and third classes of modes affect the interaction of the c-ring with its counterparts in F-O, namely subunits a and bb'. These modes are likely to be involved in ion-translocation and torque generation. The second class of deformation, along with deformations of subunits gamma and epsilon might serve to elastically buffer the torque transmission between F-O and F-1.
ISSN: 19326203
DOI: 10.1371/journal.pone.0043045

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