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

Satoshi Ohnishi, Naoya Tochio, Tadashi Tomizawa, Ryogo Akasaka, Takushi Harada, Eiko Seki, Manami Sato, Satoru Watanabe, Yukiko Fujikura, Seizo Koshiba, Takaho Terada, Mikako Shirouzu, Akiko Tanaka, Takanori Kigawa, Shigeyuki Yokoyama

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


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 × 10 2 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 α-helix was predicted. An NMR structural determination confirmed the formation of an α-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 α-helix stabilized the global fold by facilitating contacts between the N-terminal linker region and the main body of the WW domain. Published by Cold Spring Harbor Laboratory Press.

Original languageEnglish
Pages (from-to)1531-1541
Number of pages11
JournalProtein Science
Issue number9
Publication statusPublished - 2008 Sept
Externally publishedYes


  • Dimerization
  • Dynamics
  • NMR
  • Stability
  • Ultracentrifuge
  • WW domain

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology


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