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

This Article Full Text Full Text (PDF) All Versions of this Article: ps.035329.108v1 17/9/1531    most recent 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 Google Scholar Articles by Ohnishi, S. Articles by Yokoyama, S. PubMed PubMed Citation Articles by Ohnishi, S. Articles by Yokoyama, S. Social Bookmarking                   What's this?

Structural basis for controlling the dimerization and stability of the WW domains of an atypical subfamily

¹ Systems and Structural Biology Center, RIKEN, Tsurumi, Yokohama 230-0045, Japan
² Department of Computational Intelligence and Systems Science, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Yokohama 226-8503, Japan
³ Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan

(RECEIVED March 14, 2008; FINAL REVISION June 12, 2008; ACCEPTED June 12, 2008)

The second WW domain in mammalian Salvador protein (SAV1 WW2) is quite atypical, as it forms a β-clam-like homodimer. The second WW domain in human MAGI1 (membrane associated guanylate kinase, WW and PDZ domain containing 1) (MAGI1 WW2) shares high sequence similarity with SAV1 WW2, suggesting comparable dimerization. However, an analytical ultracentrifugation study revealed that MAGI1 WW2 (Leu355–Pro390) chiefly exists as a monomer at low protein concentrations, with an association constant of 1.3 x 10² M^–1. We determined its solution structure, and a structural comparison with the dimeric SAV1 WW2 suggested that an Asp residue is crucial for the inhibition of the dimerization. The substitution of this acidic residue with Ser resulted in the dimerization of MAGI1 WW2. The spin-relaxation data suggested that the MAGI1 WW2 undergoes a dynamic process of transient dimerization that is limited by the charge repulsion. Additionally, we characterized a longer construct of this WW domain with a C-terminal extension (Leu355–Glu401), as the formation of an extra -helix was predicted. An NMR structural determination confirmed the formation of an -helix in the extended C-terminal region, which appears to be independent from the dimerization regulation. A thermal denaturation study revealed that the dimerized MAGI1 WW2 with the Asp-to-Ser mutation gained apparent stability in a protein concentration-dependent manner. A structural comparison between the two constructs with different lengths suggested that the formation of the C-terminal -helix stabilized the global fold by facilitating contacts between the N-terminal linker region and the main body of the WW domain.

Keywords: WW domain; dimerization; stability; dynamics; ultracentrifuge; NMR

CiteULike

Connotea

Del.icio.us

Digg

Reddit

Technorati