| Popis: |
DNA double-strand break (DSB) is a dangerous type of DNA damage, but it also serves in controlled increase of genetic variability. The two major DSB repair pathways are homologous recombination (HR) using homologous sequences and non- homologous end joining (C-NHEJ). Two model plants Arabidopsis thaliana (Arabidopsis) and the moss Physcomitrella patens (Physcomitrella) differ in DSB repair strategies. Arabidopsis uses C-NHEJ, however Physcomitrella prefers HR. These plant models are compared on the basis of measurement of DSB and single strand breaks (SSB) repair by comet assay. The half-life of the first rapid phase of the DSB repair is about 5 minutes in both plant species. Although the C-NHEJ is considered as the main DSB repair pathway in Arabidopsis, rapid repair is independent of AtLIG4 and AtKu80, suggesting the existence of the effective backup non-homologous repair pathways (A-NHEJ). In Physcomitrella, the rapid DBS repair dominates in mitotically active cells and is also independent of PpLIG4. Conversely, PpLIG4 is surprisingly involved in the repair of the DNA alkylation damage. An essential DNA ligase of the rapid DSB repair pathway in Arabidopsis is the replication ligase AtLIG1, which is also responsible for the alkylation DNA damage repair, and thus represents a functional homolog of... |
