Redox Regulation of Carbonic Anhydrases via Thioredoxin in Chloroplast of the Marine Diatom Phaeodactylum tricornutum

• DOI: 10.1074/jbc.m111.322743
• Publication Date: 2012-04-26T03:15:16Z
• Authors: Sae Kikutani; Rie Tanaka; Yukiko Yamazaki; Satoshi Hara; Toru Hisabori; Peter G. Kroth; Yusuke Matsuda
• Keywords: Phaeodactylum tricornutum; Pyrenoid; Dithiothreitol; Carbon fixation

Thioredoxins (Trxs) are important regulators of photosynthetic fixation CO(2) and nitrogen in plant chloroplasts. To date, they have been considered to play a minor role controlling the Calvin cycle marine diatoms, aquatic primary producers, although diatoms possess set plastidic Trxs. In this study we examined influences redox state involvement Trxs enzymatic activities pyrenoidal carbonic anhydrases, PtCA1 PtCA2, diatom Phaeodactylum tricornutum. The recombinant mature -2 (mPtCA1 -2) were completely inactivated following oxidation by 50 μm CuCl(2), whereas DTT activated CAs concentration-dependent manner. maximum activity mPtCAs presence 6 mm reduced increased significantly addition 10 from Arabidopsis thaliana (AtTrx-f2 -m2) 5 P. tricornutum (PtTrxF -M). Analyses mPtCA activation revealed that mPtCA1 was enhanced ∼3-fold Trx, mPtCA2 only weakly Trxs, PtTrxs activate PtCAs more efficiently compared with AtTrxs. Site-directed mutagenesis potential disulfide-forming cysteines resulted lack oxidative inactivation both mPtCAs. These results reveal first direct evidence target indicating may participate control inorganic carbon flow pyrenoid, focal point CO(2)-concentrating mechanism.