help button home button Biophys. J.
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
Biophys. J. BioFAST: First Published October 6, 2006. doi:10.1529/biophysj.106.090035
© 2006 by the Biophysical Society.

A more recent version of this article appeared on January 1, 2007.
This Article
Right arrow Full Text (Rapid PDF)
Right arrow All Versions of this Article:
biophysj.106.090035v1
92/1/172    most recent
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Naber, N.
Right arrow Articles by Cooke, R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Naber, N.
Right arrow Articles by Cooke, R.

MUSCLE AND CONTRACTILITY

DYNAMICS OF THE NUCLEOTIDE POCKET OF MYOSIN MEASURED BY SPIN-LABELED NUCLEOTIDES

Nariman Naber 1*, Thomas J Purcell 1, Edward Pate 2 and Roger Cooke 3

1 University of California, San Francisco
2 Washinton State University
3 Univ. of California - SF

* To whom correspondence should be addressed. E-mail: nariman.naber{at}ucsf.edu.

Submitted on May 31, 2006
Revised on July 30, 2006
Accepted on 11 September 2006


  Abstract
We have used electron paramagnetic probes attached to the ribose of ATP (SL-ATP) to monitor conformational changes in the nucleotide pocket of myosin. Spectra for analogs bound to myosin in the absence of actin showed a high degree of immobilization, indicating a closed nucleotide pocket. In the Actin•Myosin•SL-AMPPNP, Actin•Myosin•SL-ADP•BeF3 and Actin•Myosin•SL-ADP•AlF4 complexes, which mimic weakly binding states near the beginning of the power-stroke, the nucleotide pocket remained closed. The spectra of the strongly bound Actin•Myosin•SL-ADP complex consisted of two components, one similar to the closed pocket and one with increased probe mobility, indicating a more open pocket, The temperature dependence of the spectra showed that the two conformations of the nucleotide pocket were in equilibrium with the open conformation more favorable at higher temperatures. These results, which show that opening of the pocket occurs only in the strongly bound states, appear reasonable, as this would tend to keep ADP bound until the end of the power-stroke. This conclusion also suggests that force is initially generated by a myosin with a closed nucleotide pocket.

Key Words: actin, electron paramagnetic resonance spectroscopy, myosin, spin probes, switch 1




This article has been cited by other articles:


Home page
 Proc. Natl. Acad. Sci. USAHome page
J. C. Klein, A. R. Burr, B. Svensson, D. J. Kennedy, J. Allingham, M. A. Titus, I. Rayment, and D. D. Thomas
Actin-binding cleft closure in myosin II probed by site-directed spin labeling and pulsed EPR
PNAS, September 2, 2008; 105(35): 12867 - 12872.
[Abstract] [Full Text] [PDF]

Home page
 Proc. Natl. Acad. Sci. USAHome page
M. Sun, M. B. Rose, S. K. Ananthanarayanan, D. J. Jacobs, and C. M. Yengo
Characterization of the pre-force-generation state in the actomyosin cross-bridge cycle
PNAS, June 24, 2008; 105(25): 8631 - 8636.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
Copyright © 2006 by the Biophysical Society.