Phylogeny, in situ hybridization service Sign up for PNAS Online eTocs
Link: Info for AuthorsLink: Editorial BoardLink: AboutLink: SubscribeLink: AdvertiseLink: ContactLink: Sitemap Link: PNAS Home
Proceedings of the National Academy of Sciences
Link: Current Issue "" Link: Archives "" Link: Online Submission ""  Link: Advanced Search

Published online on March 14, 2006, 10.1073/pnas.0509016103
PNAS | March 21, 2006 | vol. 103 | no. 12 | 4451-4456


This Article
Right arrow Figures Only
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Supporting Information
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a colleague
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My File Cabinet
Right arrow Download to citation manager
Right arrow Request Copyright Permission
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via ISI Web of Science (14)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Bullard, B.
Right arrow Articles by Oberhauser, A. F.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Bullard, B.
Right arrow Articles by Oberhauser, A. F.
Social Bookmarking
Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg  
What's this?

 Previous Article  | Table of Contents |  Next Article 

BIOLOGICAL SCIENCES / BIOPHYSICS
The molecular elasticity of the insect flight muscle proteins projectin and kettin

Belinda Bullard*,{dagger}, Tzintzuni Garcia{ddagger}, Vladimir Benes*, Mark C. Leake§,¶, Wolfgang A. Linke§,||, and Andres F. Oberhauser{ddagger},**

*European Molecular Biology Laboratory, D-69012 Heidelberg, Germany; {ddagger}Department of Neuroscience and Cell Biology and Sealy Center for Structural Biology, University of Texas Medical Branch, Galveston, TX 77555; §Institute of Physiology, University of Heidelberg, D-69120 Heidelberg, Germany; Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom; and ||Physiology and Biophysics Laboratory, University of Muenster, D-48149 Muenster, Germany

Edited by James A. Spudich, Stanford University School of Medicine, Stanford, CA, and approved December 28, 2005 (received for review October 14, 2005)

Projectin and kettin are titin-like proteins mainly responsible for the high passive stiffness of insect indirect flight muscles, which is needed to generate oscillatory work during flight. Here we report the mechanical properties of kettin and projectin by single-molecule force spectroscopy. Force–extension and force-clamp curves obtained from Lethocerus projectin and Drosophila recombinant projectin or kettin fragments revealed that fibronectin type III domains in projectin are mechanically weaker (unfolding force, Fu {approx} 50–150 pN) than Ig-domains (Fu {approx} 150–250 pN). Among Ig domains in Sls/kettin, the domains near the N terminus are less stable than those near the C terminus. Projectin domains refolded very fast [85% at 15 s–1 (25°C)] and even under high forces (15–30 pN). Temperature affected the unfolding forces with a Q10 of 1.3, whereas the refolding speed had a Q10 of 2–3, probably reflecting the cooperative nature of the folding mechanism. High bending rigidities of projectin and kettin indicated that straightening the proteins requires low forces. Our results suggest that titin-like proteins in indirect flight muscles could function according to a folding-based-spring mechanism.

force spectroscopy | refolding | single molecule | titin

{dagger}Present address: Department of Biology, University of York, York YO10 5DD, United Kingdom.

Author contributions: W.A.L. and A.F.O. designed research; T.G., M.C.L., W.A.L., and A.F.O. performed research; B.B., V.B., and A.F.O. contributed new reagents/analytic tools; A.F.O. analyzed data; and M.C.L. and A.F.O. wrote the paper.

Conflict of interest statement: No conflicts declared.

This paper was submitted directly (Track II) to the PNAS office.

**To whom correspondence should be addressed. E-mail: afoberha{at}utmb.edu

© 2006 by The National Academy of Sciences of the USA


Add to CiteULike CiteULike   Add to Complore Complore   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg    What's this?


This article has been cited by other articles in HighWire Press-hosted journals:


Home page
 J. Biol. Chem.Home page
A. F. Oberhauser and M. Carrion-Vazquez
Mechanical Biochemistry of Proteins One Molecule at a Time
J. Biol. Chem., March 14, 2008; 283(11): 6617 - 6621.
[Abstract] [Full Text] [PDF]

Home page
 J. Biol. Chem.Home page
R. D. S. Dixon, D. K. Arneman, A. S. Rachlin, N. R. Sundaresan, M. J. Costello, S. L. Campbell, and C. A. Otey
Palladin Is an Actin Cross-linking Protein That Uses Immunoglobulin-like Domains to Bind Filamentous Actin
J. Biol. Chem., March 7, 2008; 283(10): 6222 - 6231.
[Abstract] [Full Text] [PDF]

Home page
 Biophys. JHome page
M. Schlierf, F. Berkemeier, and M. Rief
Direct Observation of Active Protein Folding Using Lock-in Force Spectroscopy
Biophys. J., December 1, 2007; 93(11): 3989 - 3998.
[Abstract] [Full Text] [PDF]

Home page
 Biophys. JHome page
S. Garcia-Manyes, J. Brujic, C. L. Badilla, and J. M. Fernandez
Force-Clamp Spectroscopy of Single-Protein Monomers Reveals the Individual Unfolding and Folding Pathways of I27 and Ubiquitin
Biophys. J., October 1, 2007; 93(7): 2436 - 2446.
[Abstract] [Full Text] [PDF]

Home page
 Proc. Natl. Acad. Sci. USAHome page
D. E. Discher, N. Bhasin, and C. P. Johnson
Covalent chemistry on distended proteins
PNAS, May 16, 2006; 103(20): 7533 - 7534.
[Full Text] [PDF]