The Crystal Structure of Plant-Specific Calcium-Binding Protein AtCBL2 in Complex with the Regulatory Domain of AtCIPK14

Mayuko Akaboshi, Hiroshi Hashimoto, Hanako Ishida, Shinya Saijo, Nozomu Koizumi, Mamoru Sato, Toshiyuki Shimizu

Research output: Contribution to journalArticlepeer-review

61 Citations (Scopus)

Abstract

Calcium signals mediate a multitude of plant responses to external stimuli. Calcineurin B-like (CBL) proteins and their target kinases, CBL-interacting protein kinases (CIPKs), represent important relays in plant calcium signaling. CBL interacts with CIPK through a conserved motif (NAF/FISL motif) within the C-terminal regulatory domain. To better understand the functional role of the CBL-CIPK system, we determined the crystal structure of AtCBL2 in complex with the regulatory domain of AtCIPK14 at 1.2 Å resolution. The NAF/FISL motif is inserted into a hydrophobic crevice within AtCBL2, accompanied by a large displacement of the helices and loop on the opposite side of the NAF/FISL motif from the C-terminal region, which shields the hydrophobic crevice in free form. Ca2+ are coordinated within four EF hands in AtCBL2 in bound form. This calcium coordination pattern differs from that in the structure of the SOS3-SOS2 complex previously reported. Structural comparison of the two structures shows that the recognition of CBL by CIPK is performed in a similar manner, but inherent interactions confer binding affinity and specificity.

Original languageEnglish
Pages (from-to)246-257
Number of pages12
JournalJournal of Molecular Biology
Volume377
Issue number1
DOIs
Publication statusPublished - 2008 Mar 14
Externally publishedYes

Keywords

  • CBL
  • CIPK
  • calcium
  • crystal structure
  • plant

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Molecular Biology

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