RNA editing and DYW-type PPR proteins in the moss Physcomitrella patens

点击翻译按钮获取中文摘要

The RNA-binding PPR (Pentatricopeptide Repeat) proteins are known to be involved in organellar RNA maturation events. Their wide expansion into large gene families with more than 400 members in angiosperms and their frequent targeting into mitochondria and chloroplasts had raised speculations on their involvement, as specificity factors, also in the abundant RNA editing events in the two plant organelles. This has recently received strong support from functional genetic analyses in Ambidopsis. Exploring a unique carboxyterminal extension, which is highly conserved in a plant-specific sub-clade of PPR proteins, the DYW domain, we have recently found that the plant-specific DYW proteins are also present in jungermanniid, but not in marchantiid liverworts. This is fully congruent with observations that RNA editing is present in the former but not in the latter liverwort class. We also found both, frequent RNA editing and DYW-type PPR protein diversity, in the isolated, basal liverwort genus Haplomitrium. We have now explored mitochondrial RNA editing diversity in the transcriptome of the experimentally amenable model moss Physcomitrella patens. In line with the above observations, we find a very limited number of RNA editing sites in Physcomitrella (11), again in congruence with a low diversity of DYW-proteins (10) now deducible from the completed moss genomic sequence. We here suggest to make use of Physcomitrella as a model system to functionally investigate DYW proteins and RNA editing, employing the novel RNA immuno co-precipitation (RIP-CHIP) methodology.