title: Evidence for a role of chloroplastic m-type thioredoxins in the biogenesis of photosystem II in Arabidopsis.
abstract: Chloroplastic m-type thioredoxins (TRX m) are essential redox regulators in the light regulation of photosynthetic metabolism. However, recent genetic studies have revealed novel functions for TRX m in meristem development, chloroplast morphology, cyclic electron flow, and tetrapyrrole synthesis. The focus of this study is on the putative role of TRX m1, TRX m2, and TRX m4 in the biogenesis of the photosynthetic apparatus in Arabidopsis (Arabidopsis thaliana). To that end, we investigated the impact of single, double, and triple TRX m deficiency on chloroplast development and the accumulation of thylakoid protein complexes. Intriguingly, only inactivation of three TRX m genes led to pale-green leaves and specifically reduced stability of the photosystem II (PSII) complex, implying functional redundancy between three TRX m isoforms. In addition, plants silenced for three TRX m genes displayed elevated levels of reactive oxygen species, which in turn interrupted the transcription of photosynthesis-related nuclear genes but not the expression of chloroplast-encoded PSII core proteins. To dissect the function of TRX m in PSII biogenesis, we showed that TRX m1, TRX m2, and TRX m4 interact physically with minor PSII assembly intermediates as well as with PSII core subunits D1, D2, and CP47. Furthermore, silencing three TRX m genes disrupted the redox status of intermolecular disulfide bonds in PSII core proteins, most notably resulting in elevated accumulation of oxidized CP47 oligomers. Taken together, our results suggest an important role for TRX m1, TRX m2, and TRX m4 proteins in the biogenesis of PSII, and they appear to assist the assembly of CP47 into PSII.
authors.affiliation: State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, 510275 Guangzhou, People's Republic of China.
authors.forename: Peng
authors.initials: P
authors.lastname: Wang
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Bing
authors.initials: B
authors.lastname: Liu
authors.forename: Dongru
authors.initials: D
authors.lastname: Feng
authors.forename: Qingen
authors.initials: Q
authors.lastname: Da
authors.forename: Peng
authors.initials: P
authors.lastname: Wang
authors.forename: Shengying
authors.initials: S
authors.lastname: Shu
authors.forename: Jianbin
authors.initials: J
authors.lastname: Su
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Jinfa
authors.initials: J
authors.lastname: Wang
authors.forename: Hong-Bin
authors.initials: HB
authors.lastname: Wang
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D054479:Chloroplast Thioredoxins / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism* / Q000648:ultrastructure; D017124:Conserved Sequence; D004220:Disulfides / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D017343:Genes, Plant; D049452:Green Fluorescent Proteins / Q000378:metabolism; D015151:Immunoblotting; D010084:Oxidation-Reduction; D010641:Phenotype; D045332:Photosystem II Protein Complex / Q000096:biosynthesis*; D018515:Plant Leaves / Q000378:metabolism; D021122:Protein Subunits / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D015203:Reproducibility of Results; D013050:Spectrometry, Fluorescence; D013879:Thioredoxins / Q000235:genetics / Q000378:metabolism*; D020524:Thylakoids / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D054479:Chloroplast Thioredoxins; D004220:Disulfides; D045332:Photosystem II Protein Complex; D021122:Protein Subunits; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; C000590494:TRX m1 protein, Arabidopsis; C000590495:TRX m2 protein, Arabidopsis; C000590496:TRX m4 protein, Arabidopsis; D002734:Chlorophyll; D049452:Green Fluorescent Proteins; D013879:Thioredoxins