RNA binding-proteins interact specifically with the Arabidopsis chloroplast psbA mRNA 5' untranslated region in a redox-dependent manner.
The 5' untranslated region (5'UTR) of the psbA mRNA (psbA encodes the PSII reaction center protein, D1) is a key site for RNA-protein interactions in the post-transcriptional regulation of gene expression. In this study, we mapped the major psbA mRNA 5'-terminus at -77 nt, and two minor termini clusters centered at -48 and -64 nt, upstream from the psbA translational start codon of Arabidopsis thaliana. RNA mobility shift, RNase protection and UV-crosslinking assays were used to characterize the interaction of chloroplast proteins with the RNA 5'UTR. RNA-protein interactions depended upon a thermolabile secondary structure and specific sequences in a 35 nt region of the 5'UTR, which were 80% conserved with the psbA 5'UTRs from five other plants. Major and minor proteins of 43- and 30-kDa, respectively, were detected by UV-crosslinking to RNA. Oxidizing conditions abolished the association of the proteins with the 5'UTR, while RNA-binding activity was recovered upon incubation with a reductant. Based on these findings, we hypothesize that post-transcriptional regulation of psbA gene expression in chloroplasts of vascular plants involves redox-dependent interactions between specific sequences in the 5'UTR and 43- and 30-kDa RNA-binding proteins.
Shen
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Y
Department of Molecular Biosciences and Biosystems Engineering, University of Hawaii, 1955 East-West Road, Honolulu, HI 96822 USA.
Danon
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Christopher
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DA
D020121:5' Untranslated Regions; D017360:Arabidopsis / Q000235:genetics*; D001483:Base Sequence; D002736:Chloroplasts / Q000235:genetics*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010084:Oxidation-Reduction; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics*; D045332:Photosystem II Protein Complex; D011485:Protein Binding; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics*; D016601:RNA-Binding Proteins / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid
D020121:5' Untranslated Regions; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D012333:RNA, Messenger; D016601:RNA-Binding Proteins