The nucleotide excision repair (NER) mechanism is responsible for removing bulky DNA damage, such as pyrimidine dimers induced by ultraviolet (UV) light. The NER pathway excises the damaged strand thr Show more
The nucleotide excision repair (NER) mechanism is responsible for removing bulky DNA damage, such as pyrimidine dimers induced by ultraviolet (UV) light. The NER pathway excises the damaged strand through incisions at the 5’ and 3’ ends of the damage, with the 5’ incision catalyzed by the XPF-ERCC1 endonuclease complex. Here, we identify an XPF ortholog in Trypanosoma brucei, the causative agent of human African trypanosomiasis (sleeping sickness). XPF-deficient parasites exhibit hypersensitivity to UV irradiation and a slower rate of DNA damage repair. Consistent with its role in DNA repair, XPF localizes to the nucleus, associating with nucleoplasmic and nucleolar regions. Additionally, we demonstrate that TbXPF protects against intra- and inter-strand crosslinks induced by cisplatin and mitomycin C, respectively. The presence of a functional NER pathway in trypanosomes suggests that these organisms are susceptible to replication- and transcription-blocking DNA damage in vivo. Under genotoxic stress, genome stability and parasite survival may heavily rely on DNA repair systems such as NER which, for this reason, could be an effective target for chemotherapeutic interventions. Show less
In this chapter several aspects of Pt(II) are highlighted that focus on the properties of Pt(II)-RNA adducts and the possibility that they influence RNA-based processes in cells. Cellular distribution Show more
In this chapter several aspects of Pt(II) are highlighted that focus on the properties of Pt(II)-RNA adducts and the possibility that they influence RNA-based processes in cells. Cellular distribution of Pt(II) complexes results in significant platination of RNA, and localization studies find Pt(II) in the nucleus, nucleolus, and a distribution of other sites in cells. Treatment with Pt(II) compounds disrupts RNA-based processes including enzymatic processing, splicing, and translation, and this disruption may be indicative of structural changes to RNA or RNA-protein complexes. Several RNA-Pt(II) adducts have been characterized in vitro by biochemical and other methods. Evidence for Pt(II) binding in non-helical regions and for Pt(II) cross-linking of internal loops has been found. Although platinated sites have been identified, there currently exists very little in the way of detailed structural characterization of RNA-Pt(II) adducts. Some insight into the details of Pt(II) coordination to RNA, especially RNA helices, can be gained from DNA model systems. Many RNA structures, however, contain complex tertiary folds and common, purine-rich structural elements that present suitable Pt(II) nucleophiles in unique arrangements which may hold the potential for novel types of platinum-RNA adducts. Future research aimed at structural characterization of platinum-RNA adducts may provide further insights into platinum-nucleic acid binding motifs, and perhaps provide a rationale for the observed inhibition by Pt(II) complexes of splicing, translation, and enzymatic processing. Show less