ジベレリンの受容と情報伝達の分子メカニズム

概要

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Gibberellin (GA) is a crucial plant hormone involved in regulating plant growth and development. GA signaling is controlled by the nuclear repressor DELLA proteins. Once plant cells receive GA molecules, the DELLA proteins are rapidly degraded through an ubiquitin-proteasome pathway resulting GA responses. In this process, the GA receptor GIBBERELLIN INSENSITIVE DWARF1 (GID1) binds two conserved sequences, DELLA and VHYNP, of the DELLA protein in a GA dependent manner and triggers DELLA protein recognition and ubiqutination by the E3 ubiquitin ligase, SCF^<SLEEPY1 (SLY1)> Crystal structures of the GA-GID1-DELLA complex revealed how GID1 discriminates active or inactive GA molecules and recognizes DELLA proteins in a GA dependent manner. GA is caught in the GA binding pocket of GID1 by forming hydrogen bond networks via three conserved polar groups in the active GA molecules and induces conformational changes in the GID1 N-terminal region to form a hydrophobic molecular surface for DELLA protein binding. DELLA protein interacts with the GID1 N-terminal surface, forming a helix bundle with a thumb-like helix from the random coil structure. The series of structural changes will trigger the DELLA protein recognition and subsequent ubiqutination by the SCF^<SLY1>.
2010-05-31