Research
| Title： | Calredoxin represents a novel type of calcium-dependent sensor-responder connected to redox regulation in the chloroplast |
|---|---|
| First author： | Hochmal, Ana Karina; Zinzius, Karen; Charoenwattanasatien, Ratana; Gaebelein, Philipp; Mutoh, Risa; Tanaka, Hideaki; Schulze, Stefan; Liu, Gai; Scholz, Martin; Nordhues, Andre; Offenborn, Jan Niklas; Petroutsos, Dimitris; Finazzi, Giovanni; Fufezan, Christian; Huang, Kaiyao; Kurisu, Genji; Hippler, Michael |
| Journal： | NATURE COMMUNICATIONS |
| Years： | 2016 |
| DOI： | 10.1038/ncomms11847 |
| Abstract： | Calcium (Ca2+) and redox signalling play important roles in acclimation processes from archaea to eukaryotic organisms. Herein we characterized a unique protein from Chlamydomonas reinhardtii that has the competence to integrate Ca2+- and redox-related signalling. This protein, designated as calredoxin (CRX), combines four Ca2+-binding EF-hands and a thioredoxin (TRX) domain. A crystal structure of CRX, at 1.6 angstrom resolution, revealed an unusual calmodulin-fold of the Ca2+-binding EF-hands, which is functionally linked via an inter-domain communication path with the enzymatically active TRX domain. CRX is chloroplast-localized and interacted with a chloroplast 2-Cys peroxiredoxin (PRX1). Ca2+-binding to CRX is critical for its TRX activity and for efficient binding and reduction of PRX1. Thereby, CRX represents a new class of Ca2+-dependent 'sensor-responder' proteins. Genetically engineered Chlamydomonas strains with strongly diminished amounts of CRX revealed altered photosynthetic electron transfer and were affected in oxidative stress response underpinning a function of CRX in stress acclimation. |
