title: AtECB1/MRL7, a thioredoxin-like fold protein with disulfide reductase activity, regulates chloroplast gene expression and chloroplast biogenesis in Arabidopsis thaliana.
abstract: Plastid-encoded RNA polymerase (PEP) is closely associated with numerous factors to form PEP complex for plastid gene expression and chloroplast development. However, it is not clear how PEP complex are regulated in chloroplast. Here, one thioredoxin-like fold protein, Arabidopsis early chloroplast biogenesis 1 (AtECB1), an allele of MRL7, was identified to regulate PEP function and chloroplast biogenesis. The knockout lines for AtECB1 displayed albino phenotype and impaired chloroplast development. The transcripts of PEP-dependent plastid genes were barely detected, suggesting that the PEP activity is almost lost in atecb1-1. Although AtECB1 was not identified in PEP complex, a yeast two-hybrid assay and pull-down experiments demonstrated that it can interact with Trx Z and FSD3, two intrinsic subunits of PEP complex, respectively. This indicates that AtECB1 may play a regulatory role for PEP-dependent plastid gene expression through these two subunits. AtECB1 contains a βαβαββα structure in the thioredoxin-like fold domain and lacks the typical C-X-X-C active site motif. Insulin assay demonstrated that AtECB1 harbors disulfide reductase activity in vitro using the purified recombinant AtECB1 protein. This showed that this thioredoxin-like fold protein, AtECB1 also has the thioredoxin activity. AtECB1 may play a role in thioredoxin signaling to regulate plastid gene expression and chloroplast development.
authors: Biology Department, Life and Environmental College, Shanghai Normal University, Shanghai 200234, China.
authors: Qing-Bo
authors: QB
authors: Yua
authors: Qian
authors: Q
authors: Ma
authors: Meng-Meng
authors: MM
authors: Kong
authors: Tuan-Tuan
authors: TT
authors: Zhao
authors: Xiao-Lei
authors: XL
authors: Zhang
authors: Que
authors: Q
authors: Zhou
authors: Chao
authors: C
authors: Huang
authors: Kang
authors: K
authors: Chong
authors: Zhong-Nan
authors: ZN
authors: Yang
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D054479:Chloroplast Thioredoxins / Q000378:metabolism; D002736:Chloroplasts / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D055786:Gene Knockout Techniques; D008969:Molecular Sequence Data; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D021381:Protein Transport; D013879:Thioredoxins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C000589129:At4g28590 protein, Arabidopsis; D054479:Chloroplast Thioredoxins; C580812:thioredoxin z, Arabidopsis; D013879:Thioredoxins; D009247:NADH, NADPH Oxidoreductases; D012321:DNA-Directed RNA Polymerases
keywords: Arabidopsis; Thioredoxin; chloroplast biogenesis.; chloroplast transcription; disulfide reductase activity