title: Protein disulfide isomerase 2 of Chlamydomonas reinhardtii is involved in circadian rhythm regulation.
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.
authors.affiliation: Institute of General Botany and Plant Physiology, Friedrich-Schiller-Universität Jena, 07743 Jena, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Filonova
authors.forename: Paul
authors.initials: P
authors.lastname: Haemsch
authors.forename: Christin
authors.initials: C
authors.lastname: Gebauer
authors.forename: Wolfram
authors.initials: W
authors.lastname: Weisheit
authors.forename: Volker
authors.initials: V
authors.lastname: Wagner
mesh_terms: D000595:Amino Acid Sequence; D016825:Chlamydomonas reinhardtii / Q000201:enzymology* / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D003624:Darkness; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D006493:Heparin / Q000378:metabolism; D047468:Immunoprecipitation; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000378:metabolism; D010084:Oxidation-Reduction; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D054464:Peroxiredoxins / Q000378:metabolism; D011485:Protein Binding; D019704:Protein Disulfide-Isomerases / Q000737:chemistry / Q000378:metabolism*; D058849:Protein Refolding; D011994:Recombinant Proteins / Q000378:metabolism
chemical_list: D046912:Multiprotein Complexes; D010455:Peptides; D011994:Recombinant Proteins; D006493:Heparin; D054464:Peroxiredoxins; D019704:Protein Disulfide-Isomerases
keywords: Chlamydomonas reinhardtii; circadian clock.; protein disulfide isomerase 2