Structural highlights
Publication Abstract from PubMedCalcium (Ca(2+)) 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 Ca(2+)- and redox-related signalling. This protein, designated as calredoxin (CRX), combines four Ca(2+)-binding EF-hands and a thioredoxin (TRX) domain. A crystal structure of CRX, at 1.6 A resolution, revealed an unusual calmodulin-fold of the Ca(2+)-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). Ca(2+)-binding to CRX is critical for its TRX activity and for efficient binding and reduction of PRX1. Thereby, CRX represents a new class of Ca(2+)-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. Calredoxin represents a novel type of calcium-dependent sensor-responder connected to redox regulation in the chloroplast.,Hochmal AK, Zinzius K, Charoenwattanasatien R, Gabelein P, Mutoh R, Tanaka H, Schulze S, Liu G, Scholz M, Nordhues A, Offenborn JN, Petroutsos D, Finazzi G, Fufezan C, Huang K, Kurisu G, Hippler M Nat Commun. 2016 Jun 14;7:11847. doi: 10.1038/ncomms11847. PMID:27297041[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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