Protein Disulfide Isomerase 2 of Chlamydomonas reinhardtii Is Involved in Circadian Rhythm Regulation

• Published in: Molecular plant Vol. 6; no. 5; pp. 1503 - 1517
• Main Authors: Filonova, Anna, Haemsch, Paul, Gebauer, Christin, Weisheit, Wolfram, Wagner, Volker
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 01.09.2013; Cell Press
• Subjects: Amino Acid Sequence; Chlamydomonas reinhardtii; Chlamydomonas reinhardtii - enzymology; Chlamydomonas reinhardtii - physiology; circadian clock; Circadian rhythm; Circadian Rhythm - physiology; Darkness; Electrophoresis, Polyacrylamide Gel; Enzyme Stability; Heparin - metabolism; Immunoprecipitation; Molecular Sequence Data; Multiprotein Complexes - metabolism; Oxidation-Reduction; Peptides - chemistry; Peptides - metabolism; Peroxiredoxins - metabolism; Protein Binding; protein disulfide isomerase 2; Protein Disulfide-Isomerases - chemistry; Protein Disulfide-Isomerases - metabolism; Protein Refolding; Proteins; Recombinant Proteins - metabolism; 二硫键异构酶; 昼夜节律; 氧化还原活性; 硫氧还蛋白还原酶; 莱茵衣藻; 蛋白质; 转基因品系; 过氧化物酶; circadian clock; Chlamydomonas reinhardtii; protein disulfide isomerase 2
• ISSN: 1674-2052; 1752-9867
• DOI: 10.1093/mp/sst048

Protein disulfide isomerases （PDIs） are known to play important roles in the folding of nascent proteins and in the formation of disulfide bonds. Recently, we identified a PDI from Chlamydomonas reinhardtii （CrPDI2） by a mass spectrometry approach that is specifically enriched by heparin affinity chromatography in samples taken during the night phase. Here, we show that the recombinant CrPDI2 is a redox-active protein. It is reduced by thioredoxin reductase and catalyzes itself the reduction of insulin chains and the oxidative refolding of scrambled RNase A. By immunoblots, we confirm a high-amplitude change in abundance of the heparin-bound CrPDI2 during subjective night. Interestingly, we find that CrPDI2 is present in protein complexes of different sizes at both day and night. Among three identified interac- tion partners, one （a 2-cys peroxiredoxin） is present only during the night phase. To study a potential function of CrPDI2 within the circadian system, we have overexpressed its gene. Two transgenic lines were used to measure the rhythm of phototaxis~ In the transgenic strains, a change in the acrophase was observed. This indicates that CrPDI2 is involved in the circadian signaling pathway and, together with the night phase-specific interaction of CrPDI2 and a peroxiredoxin, these findings suggest a close coupling of redox processes and the circadian clock in C. reinhardtii.