RESUMO
After reconstitution of nucleotide excision repair (excision repair) with XPA, RPA, XPC, TFIIH, XPF-ERCC1 and XPG, it was concluded that these six factors are the minimal essential components of the excision repair machinery. All six factors are highly conserved across diverse organisms spanning yeast to humans, yet no identifiable homolog of the XPA gene exists in many eukaryotes including green plants. Nevertheless, excision repair is reported to be robust in the XPA-lacking organism, Arabidopsis thaliana, which raises a fundamental question of whether excision repair could occur without XPA in other organisms. Here, we performed a phylogenetic analysis of XPA across all species with annotated genomes and then quantitatively measured excision repair in the absence of XPA using the sensitive whole-genome qXR-Seq method in human cell lines and two model organisms, Caenorhabditis elegans and Drosophila melanogaster. We find that although the absence of XPA results in inefficient excision repair and UV-sensitivity in humans, flies, and worms, excision repair of UV-induced DNA damage is detectable over background. These studies have yielded a significant discovery regarding the evolution of XPA protein and its mechanistic role in nucleotide excision repair.
Assuntos
Reparo por Excisão , Proteína de Xeroderma Pigmentoso Grupo A , Animais , Humanos , Dano ao DNA , Reparo do DNA , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Drosophila melanogaster/metabolismo , Nucleotídeos/metabolismo , Filogenia , Proteína de Xeroderma Pigmentoso Grupo A/genética , Proteína de Xeroderma Pigmentoso Grupo A/metabolismo , Plantas/metabolismo , Evolução MolecularRESUMO
A novel type of phthalocyanine pentad containing four boron dipyrromethene (BODIPY) units at peripheral positions of the phthalocyanine framework has been designed and synthesized for the first time. The Sonogashira coupling reaction between 4,4'-difluoro-8-(4-ethynyl)-phenyl-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene (Ethynyl-BODIPY) and 2(3),9(10),16(17),23(24)-tetrakis(iodo) zinc(ii) phthalocyanine (Iodo-Pc) has been used for the synthesis of the target compound. The BODIPY-phthalocyanine pentad dye (BODIPY-Pc) has been fully characterized by (1)H NMR, MALDI-TOF mass, FT-IR and UV-Vis spectroscopic techniques and elemental analysis as well. The photoinduced energy transfer process for this dye system was explored in tetrahydrofuran solution. The singlet oxygen generation capability and photodegradation behaviours of this BODIPY-Pc pentad dye were also investigated in DMSO for the determination of the usability of this new type of dye system as a photosensitizer in PDT applications.
