title: Knockdown of the Arabidopsis thaliana chloroplast protein disulfide isomerase 6 results in reduced levels of photoinhibition and increased D1 synthesis in high light.
abstract: A chloroplast protein disulfide isomerase (PDI) was previously proposed to regulate translation of the unicellular green alga Chlamydomonas reinhardtii chloroplast psbA mRNA, encoding the D1 protein, in response to light. Here we show that AtPDI6, one of 13 Arabidopsis thaliana PDI genes, also plays a role in the chloroplast. We found that AtPDI6 is targeted and localized to the chloroplast. Interestingly, AtPDI6 knockdown plants displayed higher resistance to photoinhibition than wild-type plants when exposed to a tenfold increase in light intensity. The AtPDI6 knockdown plants also displayed a higher rate of D1 synthesis under a similar light intensity. The increased resistance to photoinhibition may not be rationalized by changes in antenna or non-photochemical quenching. Thus, the increased D1 synthesis rate, which may result in a larger proportion of active D1 under light stress, may led to the decrease in photoinhibition. These results suggest that, although the D1 synthesis rates observed in wild-type plants under high light intensities are elevated, repair can potentially occur faster. The findings implicate AtPDI6 as an attenuator of D1 synthesis, modulating photoinhibition in a light-regulated manner.
authors.affiliation: Department of Plant Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel.
authors.forename: Gal
authors.initials: G
authors.lastname: Wittenberg
authors.forename: Alexander
authors.initials: A
authors.lastname: Levitan
authors.forename: Tamir
authors.initials: T
authors.lastname: Klein
authors.forename: Inbal
authors.initials: I
authors.lastname: Dangoor
authors.forename: Nir
authors.initials: N
authors.lastname: Keren
authors.forename: Avihai
authors.initials: A
authors.lastname: Danon
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D060365:Chloroplast Proteins / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D055785:Gene Knockdown Techniques; D055537:Light Signal Transduction; D045332:Photosystem II Protein Complex / Q000096:biosynthesis*; D019704:Protein Disulfide-Isomerases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D060365:Chloroplast Proteins; D045332:Photosystem II Protein Complex; D012333:RNA, Messenger; C000595435:PDI6 protein, Arabidopsis; D019704:Protein Disulfide-Isomerases
keywords: Arabidopsis thaliana; D1 turnover; chloroplast; photoinhibition; photosystem II; protein disulfide isomerase