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

J. Biol. Chem., Vol. 279, Issue 14, 13452-13460, April 2, 2004

This Article Full Text Full Text (PDF) All Versions of this Article: 279/14/13452    most recent M313593200v1 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 Grant, G. A. Articles by Hu, Z. Search for Related Content PubMed PubMed Citation Articles by Grant, G. A. Articles by Hu, Z. Social Bookmarking                      What's this?

Quantitative Relationships of Site to Site Interaction in Escherichia coli D-3-Phosphoglycerate Dehydrogenase Revealed by Asymmetric Hybrid Tetramers^*

Gregory A. Grant, Xiao Lan Xu, and Zhiqin Hu

From the Department of Molecular Biology and Pharmacology and Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110

A set of asymmetric hybrid tetramers of Escherichia coli D-3-phosphoglycerate dehydrogenase (PGDH) have been made by gene co-expression and KSCN-induced dimer exchange. These tetramers contain varied numbers of active sites and effector binding sites arranged in different orientations within the tetramer. They reveal that PGDH displays half-of-the-sites activity with respect to its active sites and that the two sites that are active at any particular time lie in subunits on either side of the nucleotide binding domain interface. Half-of-the-sites functionality is also observed for the effector even though all four sites eventually bind effector. That is, only two effector sites need to be occupied for maximum inhibition. Binding of the last two effector molecules does not contribute functionally to inhibition of activity. Furthermore, positive cooperativity of inhibition of activity by the effector is completely dependent on the positive cooperativity of binding of the effector. Binding of the first effector molecule produces a conformational change that essentially completely inhibits the active site within the subunit to which it binds and produces an approximate 33% inhibition of the active site in the subunit to which it is not bound. Binding of the second effector at the opposite regulatory domain interface completes the inhibition of activity. This simple relationship defines the positional and quantitative influence of effector ligand binding on activity and can be used to predict the maximum level of inhibition of individual hybrid tetramers. In addition, the site-specific quantitative relationship of effector binding to individual active sites can be used to model the inhibition profile with relatively good agreement. These simple rules for the site to site interaction in PGDH provide significant new insight into the mechanism of allostery of this enzyme.

Received for publication, December 10, 2003 , and in revised form, January 7, 2004.

^* This work was supported by Grant GM 56676 from the National Institutes of Health. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

To whom correspondence should be addressed: Dept. of Molecular Biology and Pharmacology, Box 8103, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110. Tel.: 314-362-3367; Fax: 314-362-4698; E-mail: ggrant{at}molecool.wustl.edu.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				S. Dey, Z. Hu, X. L. Xu, J. C. Sacchettini, and G. A. Grant The Effect of Hinge Mutations on Effector Binding and Domain Rotation in Escherichia coli D-3-Phosphoglycerate Dehydrogenase J. Biol. Chem., June 22, 2007; 282(25): 18418 - 18426. [Abstract] [Full Text] [PDF]

				S. Dey, Z. Hu, X. L. Xu, J. C. Sacchettini, and G. A. Grant D-3-Phosphoglycerate Dehydrogenase from Mycobacterium tuberculosis Is a Link between the Escherichia coli and Mammalian Enzymes J. Biol. Chem., April 15, 2005; 280(15): 14884 - 14891. [Abstract] [Full Text] [PDF]