Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.5.1.4 (deaminase)
 5,113 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

C-to-U RNA editing (i.e., alteration of a C in the genomic sequence to U in the transcript) has been confirmed widely in angiosperm organellar genomes. During the C-to-U RNA editing event, incomplete edited transcripts have been observed at many sites in the steady-state mRNA population (partial editing). Here, by using coexpression analysis and the surveillance of whole editing status on the mitochondrial genome, we have revealed that a pentatricopeptide repeat (PPR) protein classified into the P subfamily (PPR596) has site-specific influence on the efficiency of C-to-U RNA editing events at partial editing sites on the Arabidopsis thaliana mitochondrial genome. Previous works have revealed that PPR proteins classified into the PLS subfamily containing the E or E and DYW motif are involved in RNA editing as trans-factors; they are believed to recruit deaminase at editing sites. In contrast with the mutant analyses of PLS-subfamily PPR proteins, the editing efficiency at rps3eU1344SS was revealed to be significantly increased in ppr596 mutants. Our study implies P-subfamily PPR protein is involved in the control of the degree of partial editing.
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PMID:The involvement of a PPR protein of the P subfamily in partial RNA editing of an Arabidopsis mitochondrial transcript. 2011 93

In plants, RNA editing is a process that deaminates specific cytidines (C) to uridines (U). PLS subfamily members of PPR proteins function in site recognition of the target C. In silico analysis has predicted the code used for PPR motif-nucleotide interaction, and the crystal structure of a protein-RNA complex supports this model. Despite progress in understanding the RNA-binding mechanism of PPR proteins, some of the flexibility of RNA recognition observed in trans-factors of RNA editing has not been fully explained. It is probably necessary to consider another unknown mechanism, and this consideration is related to the question of how PPR proteins have managed the creation of RNA editing sites during evolution. This question may be related to the mystery of the biological function of RNA editing in plants. MORF/RIP family members are required for RNA editing at multiple editing sites and are components of the RNA editosome in plants. The DYW domain has been a strong candidate for the C deaminase activity required for C-to-U conversion in RNA editing. So far, the activity of this enzyme has not been detected in recombinant DYW proteins, and several puzzling experimental results need to be explained to support the model. It is still difficult to resolve the entire image of the editosome in RNA editing in plants. This article is part of a Special Issue entitled: Chloroplast Biogenesis.
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PMID:RNA editing in plants: Machinery and flexibility of site recognition. 2558 61

Pentatricopeptide repeat (PPR) proteins, composed of PPR motifs repeated in tandem, are sequence-specific RNA binding proteins. Recent bioinformatic studies have shown that the combination of polar amino acids at positions 5 and last in each PPR motif recognizes RNA bases, and an RNA recognition code for PPR proteins has been proposed. Subsequent studies confirmed that the P (canonical length) and S (short) motifs bind to specific nucleotides according to this code. However, the contribution of L (long) motifs to RNA recognition is mostly controversial, owing to the presence of a nonpolar amino acid at position 5. The PLS-class PPR protein PpPPR_56 is a mitochondrial RNA editing factor in the moss Physcomitrella patens. Here, we performed in vitro RNA binding and in vivo complementation assays with PpPPR_56 and its variants containing mutated L motifs to investigate their contributions to RNA recognition. In vitro RNA binding assay showed that the original combination of amino acids at positions 5 and last in the L motifs of PpPPR_56 is not required for RNA recognition. In addition, an in vivo complementation assay with RNA editing factors PpPPR_56 and PpPPR_78 revealed the importance of nonpolar amino acids at position 5 of C-terminal L motifs for efficient RNA editing. Our findings suggest that L motifs function as non-binding spacers, not as RNA-binding motifs, to facilitate the formation of a complex between PLS-class PPR protein and RNA. As a result, the DYW domain, a putative catalytic deaminase responsible for C-to-U RNA editing, is correctly placed in proximity to C, which is to be edited.
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PMID:The L motifs of two moss pentatricopeptide repeat proteins are involved in RNA editing but predominantly not in RNA recognition. 3234 68