HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 276, Issue 9, 6253-6259, March 2, 2001

This Article Full Text Full Text (PDF) All Versions of this Article: 276/9/6253    most recent M009530200v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Panda, M. Articles by Horowitz, P. M. Search for Related Content PubMed PubMed Citation Articles by Panda, M. Articles by Horowitz, P. M. Social Bookmarking                      What's this?

High Hydrostatic Pressure Can Probe the Effects of Functionally Related Ligands on the Quaternary Structures of the Chaperonins GroEL and GroES^*

Markandeswar Panda, Jesse Ybarra, and Paul M. Horowitz

From the Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229-3900

We investigated the effects of high hydrostatic pressure in the range of 1-3 kilobars on tetradecameric GroEL, heptameric GroES, and the GroEL-GroES complex. Unlike GroEL monomers formed by urea dissociation, which can be reassembled back to the tetradecamer, the pressure-dissociated monomers do not reassemble readily. This indicates an alteration of their native structures, an example of conformational drift. Pressure versus time profiles and kinetics of the dissociation of both GroEL and GroES at fixed pressures were monitored by light scattering. Unlike GroEL, GroES monomers do reassociate readily. Reaction conditions were varied by adding ATP, Mg²⁺, ADP, AMP-PNP, and KCl. At any individual pressure, the dissociation process is governed by both thermodynamics and kinetics. This leads to the decrease in the yield of monomers at lower pressures. In the presence of Mg²⁺ and KCl, GroEL is stable up to 3 kilobars. The presence of either ATP or ADP but not AMP-PNP leads to GroEL dissociation at lower pressures. Interestingly, the GroEL-GroES complex is very stable in the range of 1-2.5 kilobars. However, the addition of ADP destabilizes the complex, which dissociates completely at 1.5 kilobars. The results are rationalized in terms of different degrees of cooperativity between individual monomers and heptameric rings in the GroEL tetradecamer. Such allosteric interactions leading to the alteration of quaternary structure of GroEL in the absence of chemical denaturants are important in understanding the mechanism of chaperonin-assisted protein folding by the GroEL-GroES system.

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

This article has been cited by other articles:

				A. T. Da Poian, J. E. Johnson, and J. L. Silva Protein-RNA Interactions and Virus Stability as Probed by the Dynamics of Tryptophan Side Chains J. Biol. Chem., November 27, 2002; 277(49): 47596 - 47602. [Abstract] [Full Text] [PDF]