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Crystal Structure of Okadaic Acid Binding Protein 2.1: A Sponge Protein Implicated in Cytotoxin Accumulation
Author(s) -
Ehara Haruhiko,
Makino Marie,
Kodama Koichiro,
Konoki Keiichi,
Ito Takuhiro,
Sekine Shunichi,
Fukuzawa Seketsu,
Yokoyama Shigeyuki,
Tachibana Kazuo
Publication year - 2015
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/cbic.201500141
Subject(s) - okadaic acid , sponge , aequorin , biochemistry , phosphatase , marine toxin , biology , serine , peptide sequence , protein phosphatase 1 , protein structure , chemistry , phosphorylation , toxin , gene , intracellular , botany
Okadaic acid (OA) is a marine polyether cytotoxin that was first isolated from the marine sponge Halichondria okadai . OA is a potent inhibitor of protein serine/threonine phosphatases (PP) 1 and 2A, and the structural basis of phosphatase inhibition has been well investigated. However, the role and mechanism of OA retention in the marine sponge have remained elusive. We have solved the crystal structure of okadaic acid binding protein 2.1 (OABP2.1) isolated from H. okadai ; it has strong affinity for OA and limited sequence homology to other proteins. The structure revealed that OABP2.1 consists of two α‐helical domains, with the OA molecule deeply buried inside the protein. In addition, the global fold of OABP2.1 was unexpectedly similar to that of aequorin, a jellyfish photoprotein. The presence of structural homologues suggested that, by using similar protein scaffolds, marine invertebrates have developed diverse survival systems adapted to their living environments.