Molecular genetic analysis of chloroplast gene promoters dependent on SIG2, a nucleus-encoded sigma factor for the plastid-encoded RNA polymerase, in Arabidopsis thaliana
AUTOR(ES)
Hanaoka, Mitsumasa
FONTE
Oxford University Press
RESUMO
Most photosynthesis-related genes in mature chloroplasts are transcribed by a eubacterial-type RNA polymerase (PEP) whose core subunits are encoded by the plastid genome. It has been shown previously that six putative nuclear genes (SIG1 to SIG6) encode promoter-specificity factors for PEP in Arabidopsis thaliana, and we isolated a T-DNA insertion line of SIG2 (sig2-1 mutant) that manifests aberrant chloroplast development. With the use of S1 nuclease protection and primer extension analyses, we have now characterized the SIG2-dependent chloroplast promoters in A.thaliana. The amounts of transcripts derived from one of the multiple psbD promoters (psbD –256) and from the promoters of two tRNA genes (trnE-UUC and trnV-UAC) were markedly and specifically decreased in the sig2-1 mutant. The abundance of these transcripts was restored to wild-type levels by introduction into the mutant of a SIG2 transgene. The recombinant SIG2 protein mixed with Escherichia coli core RNA polymerase could bind to a DNA fragment that contains the SIG2-dependent psbD –256, trnE-UUC or trnV-UAC promoter. Sequences similar to those of the –35 and –10 promoter elements of E.coli were identified in the regions of the SIG2-dependent chloroplast genes upstream of the transcription initiation sites.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=291874Documentos Relacionados
- AtSig5 Is an Essential Nucleus-Encoded Arabidopsis σ-Like Factor1
- RNA Polymerase Subunits Encoded by the Plastid rpo Genes Are Not Shared with the Nucleus-Encoded Plastid Enzyme1
- Blue light-induced transcription of plastid-encoded psbD gene is mediated by a nuclear-encoded transcription initiation factor, AtSig5
- Nucleus-Encoded Genes for Plastid-Targeted Proteins in Helicosporidium: Functional Diversity of a Cryptic Plastid in a Parasitic Alga†
- Analysis of the nucleus-encoded and chloroplast-targeted rieske protein by classic and site-directed mutagenesis of Chlamydomonas.