title: The natural absence of RPA1N domain did not impair Leishmania amazonensis RPA-1 participation in DNA damage response and telomere protection.
abstract: We have previously shown that the subunit 1 of Leishmania amazonensis RPA (LaRPA-1) alone binds the G-rich telomeric strand and is structurally different from other RPA-1. It is analogous to telomere end-binding proteins described in model eukaryotes whose homologues were not identified in the protozoan´s genome. Here we show that LaRPA-1 is involved with damage response and telomere protection although it lacks the RPA1N domain involved with the binding with multiple checkpoint proteins. We induced DNA double-strand breaks (DSBs) in Leishmania using phleomycin. Damage was confirmed by TUNEL-positive nuclei and triggered a G1/S cell cycle arrest that was accompanied by nuclear accumulation of LaRPA-1 and RAD51 in the S phase of hydroxyurea-synchronized parasites. DSBs also increased the levels of RAD51 in non-synchronized parasites and of LaRPA-1 and RAD51 in the S phase of synchronized cells. More LaRPA-1 appeared immunoprecipitating telomeres in vivo and associated in a complex containing RAD51, although this interaction needs more investigation. RAD51 apparently co-localized with few telomeric clusters but it did not immunoprecipitate telomeric DNA. These findings suggest that LaRPA-1 and RAD51 work together in response to DNA DSBs and at telomeres, upon damage, LaRPA-1 works probably to prevent loss of single-stranded DNA and to assume a capping function.
authors: Departamento de Genética, Instituto de Biociências, Universidade Estadual Paulista Júlio de Mesquita Filho, Botucatu, SP, 18618-970, Brazil.
authors: Rita De Cássia Viveiros
authors: Rde C
authors: Da Silveira
authors: Marcelo Santos
authors: MS
authors: Da Silva
authors: Vinícius Santana
authors: VS
authors: Nunes
authors: Arina Marina
authors: AM
authors: Perez
authors: Maria Isabel Nogueira
authors: MI
authors: Cano
mesh_terms: D059447:Cell Cycle Checkpoints / Q000187:drug effects; D053903:DNA Breaks, Double-Stranded; D020287:In Situ Nick-End Labeling; D007891:Leishmania / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D010692:Phleomycins / Q000494:pharmacology; D015800:Protozoan Proteins / Q000378:metabolism*; D016615:Telomere / Q000378:metabolism*
chemical_list: D019384:Nucleic Acid Synthesis Inhibitors; D010692:Phleomycins; D015800:Protozoan Proteins