Calredoxin represents a novel type of calcium-dependent sensor-responder connected to redox regulation in the chloroplast.
Calcium (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 Å 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.
Institute of Plant Biology and Biotechnology, University of Münster, 48143 Münster, Germany.
Ana Karina
AK
Hochmal
Institute of Plant Biology and Biotechnology, University of Münster, 48143 Münster, Germany.
Karen
K
Zinzius
Institute for Protein Research, Osaka University, Suita Osaka 565-0871, Japan.
Ratana
R
Charoenwattanasatien
Institute of Plant Biology and Biotechnology, University of Münster, 48143 Münster, Germany.
Philipp
P
Gäbelein
Institute for Protein Research, Osaka University, Suita Osaka 565-0871, Japan.|Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Saitama 332-0012, Japan.
Risa
R
Mutoh
Institute for Protein Research, Osaka University, Suita Osaka 565-0871, Japan.|Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Saitama 332-0012, Japan.
Hideaki
H
Tanaka
Institute of Plant Biology and Biotechnology, University of Münster, 48143 Münster, Germany.
Stefan
S
Schulze
Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China.
Gai
G
Liu
Institute of Plant Biology and Biotechnology, University of Münster, 48143 Münster, Germany.
Martin
M
Scholz
Institute of Plant Biology and Biotechnology, University of Münster, 48143 Münster, Germany.
André
A
Nordhues
Institute of Plant Biology and Biotechnology, University of Münster, 48143 Münster, Germany.
Jan Niklas
JN
Offenborn
Centre National Recherche Scientifique, Unité Mixte Recherche 5168, Laboratoire Physiologie Cellulaire et Végétale, F-38054 Grenoble, France.|Commissariat à l'Energie Atomique et Energies Alternatives, l'Institut de Recherches en Technologies et Sciences pour le Vivant, F-38054 Grenoble, France.|Université Grenoble 1, F-38041 Grenoble, France.|Institut National Recherche Agronomique, UMR1200, F-38054 Grenoble, France.
Dimitris
0000-0002-9656-661X
D
Petroutsos
Centre National Recherche Scientifique, Unité Mixte Recherche 5168, Laboratoire Physiologie Cellulaire et Végétale, F-38054 Grenoble, France.|Commissariat à l'Energie Atomique et Energies Alternatives, l'Institut de Recherches en Technologies et Sciences pour le Vivant, F-38054 Grenoble, France.|Université Grenoble 1, F-38041 Grenoble, France.|Institut National Recherche Agronomique, UMR1200, F-38054 Grenoble, France.
Giovanni
G
Finazzi
Institute of Plant Biology and Biotechnology, University of Münster, 48143 Münster, Germany.
Christian
C
Fufezan
Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China.
Kaiyao
K
Huang
Institute for Protein Research, Osaka University, Suita Osaka 565-0871, Japan.|Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Saitama 332-0012, Japan.
Genji
G
Kurisu
Institute of Plant Biology and Biotechnology, University of Münster, 48143 Münster, Germany.
Michael
M
Hippler
D001665:Binding Sites; D002118:Calcium / Q000737:chemistry* / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002147:Calmodulin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016825:Chlamydomonas reinhardtii / Q000235:genetics* / Q000378:metabolism; D002736:Chloroplasts / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D004579:Electron Transport; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D008958:Models, Molecular; D010084:Oxidation-Reduction; D054464:Peroxiredoxins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010788:Photosynthesis / Q000235:genetics; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D011485:Protein Binding; D000072756:Protein Conformation, alpha-Helical; D000072757:Protein Conformation, beta-Strand; D017510:Protein Folding; D054730:Protein Interaction Domains and Motifs; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013879:Thioredoxins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D002135:Calcium-Binding Proteins; D002147:Calmodulin; D010940:Plant Proteins; D011994:Recombinant Proteins; D013879:Thioredoxins; D054464:Peroxiredoxins; D002118:Calcium