PMID:23475997

Citation	Filonova, A, Haemsch, P, Gebauer, C, Weisheit, W and Wagner, V (2013) Protein disulfide isomerase 2 of Chlamydomonas reinhardtii is involved in circadian rhythm regulation. Mol Plant 6:1503-17
Abstract	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 interaction 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.
Links	PubMed Online version:10.1093/mp/sst048
Keywords	Amino Acid Sequence; Chlamydomonas reinhardtii/enzymology; Chlamydomonas reinhardtii/physiology; 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-Isomerases/chemistry; Protein Disulfide-Isomerases/metabolism; Protein Refolding; Recombinant Proteins/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
CHLRE:O48949	enables	GO:0003756: protein disulfide isomerase activity	ECO:0000314: direct assay evidence used in manual assertion		F		Seeded From UniProt	complete
CHLRE:O48949		GO:0003756: protein disulfide isomerase activity	ECO:0000314:		F		Figure 1D. An RNase activity assay shows that denatured RNase A was refolded in the presence of CPI2. The controls were fully active RNase A and RNase A without CPI2.	complete CACAO 9883

References

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