RESUMEN
Structural maintenance of chromosomes (SMC) complexes are molecular machines ensuring chromatin organization at higher levels. They play direct roles in cohesion, condensation, replication, transcription, and DNA repair. Their cores are composed of long-armed SMC, kleisin, and kleisin-associated subunits. Additional factors, like NSE6 within SMC5/6, bind to SMC core complexes and regulate their activities. In the human HsNSE6/SLF2, we recently identified a new CANIN domain. Here we tracked down its sequence homology to lower plants, selected the bryophyte Physcomitrium patens, and analyzed PpNSE6 protein-protein interactions to explore its conservation in detail. We identified a previously unrecognized core sequence motif conserved from yeasts to humans within the NSE6 CANIN domain. This motif mediates the interaction between NSE6 and its NSE5 partner in yeasts and plants. In addition, the CANIN domain and its preceding PpNSE6 sequences bind both PpSMC5 and PpSMC6 arms. Interestingly, we mapped the PpNSE6-binding site at the PpSMC5 arm right next to the PpNSE2-binding surface. The position of NSE6 at SMC arms suggests its role in the regulation of SMC5/6 dynamics. Consistent with the regulatory role of NSE6 subunits, Ppnse6 mutant lines were viable and sensitive to the DNA-damaging drug bleomycin and lost a large portion of rDNA copies. These moss mutants also exhibited reduced growth and developmental aberrations. Altogether, our data showed the conserved function of the NSE6 subunit and architecture of the SMC5/6 complex across species.
Asunto(s)
Proteínas Cromosómicas no Histona , Reparación del ADN , Humanos , Proteínas Cromosómicas no Histona/metabolismo , Cromosomas , Dominios Proteicos , Proteínas de Ciclo Celular/metabolismoRESUMEN
The proper repair of deleterious DNA lesions such as double strand breaks prevents genomic instability and carcinogenesis. In yeast, the Rad52 protein mediates DSB repair via homologous recombination. In mammalian cells, despite the presence of the RAD52 protein, the tumour suppressor protein BRCA2 acts as the predominant mediator during homologous recombination. For decades, it has been believed that the RAD52 protein played only a back-up role in the repair of DSBs performing an error-prone single strand annealing (SSA). Recent studies have identified several new functions of the RAD52 protein and have drawn attention to its important role in genome maintenance. Here, we show that RAD52 activities are enhanced by interacting with a small and highly acidic protein called DSS1. Binding of DSS1 to RAD52 changes the RAD52 oligomeric conformation, modulates its DNA binding properties, stimulates SSA activity and promotes strand invasion. Our work introduces for the first time RAD52 as another interacting partner of DSS1 and shows that both proteins are important players in the SSA and BIR pathways of DSB repair.
Asunto(s)
Carcinogénesis/genética , Recombinación Homóloga/genética , Complejo de la Endopetidasa Proteasomal/genética , Proteína Recombinante y Reparadora de ADN Rad52/genética , Proteína BRCA2/genética , Roturas del ADN de Doble Cadena , Reparación del ADN/genética , Proteínas de Unión al ADN/genética , Genoma Humano/genética , Inestabilidad Genómica/genética , Humanos , Osteosarcoma/genética , Osteosarcoma/patología , Unión Proteica , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genéticaRESUMEN
Replication across damaged DNA templates is accompanied by transient formation of sister chromatid junctions (SCJs). Cells lacking Esc2, an adaptor protein containing no known enzymatic domains, are defective in the metabolism of these SCJs. However, how Esc2 is involved in the metabolism of SCJs remains elusive. Here we show interaction between Esc2 and a structure-specific endonuclease Mus81-Mms4 (the Mus81 complex), their involvement in the metabolism of SCJs, and the effects Esc2 has on the enzymatic activity of the Mus81 complex. We found that Esc2 specifically interacts with the Mus81 complex via its SUMO-like domains, stimulates enzymatic activity of the Mus81 complex in vitro, and is involved in the Mus81 complex-dependent resolution of SCJs in vivo Collectively, our data point to the possibility that the involvement of Esc2 in the metabolism of SCJs is, in part, via modulation of the activity of the Mus81 complex.
Asunto(s)
Cromátides/metabolismo , ADN Cruciforme/metabolismo , Proteínas de Unión al ADN/genética , Endonucleasas/genética , Regulación Fúngica de la Expresión Génica , Proteínas Nucleares/genética , Proteínas de Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/genética , Proteínas de Ciclo Celular , Cromátides/química , Clonación Molecular , Daño del ADN , Replicación del ADN , ADN Cruciforme/química , ADN de Hongos/genética , ADN de Hongos/metabolismo , Proteínas de Unión al ADN/química , Proteínas de Unión al ADN/metabolismo , Endonucleasas/química , Endonucleasas/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Inestabilidad Genómica , Proteínas Nucleares/química , Proteínas Nucleares/metabolismo , Unión Proteica , Dominios Proteicos , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas Modificadoras Pequeñas Relacionadas con Ubiquitina/química , Proteínas Modificadoras Pequeñas Relacionadas con Ubiquitina/genética , Proteínas Modificadoras Pequeñas Relacionadas con Ubiquitina/metabolismoRESUMEN
Given the key role of mitochondria in various cellular events, it is not surprising that mitochondrial dysfunction (MDF) is seen in many pathological conditions, in particular cancer. The mechanisms defining MDF are not clearly understood and may involve genetic defects, misbalance of reactive oxygen species (ROS), impaired autophagy (mitophagy), acquired mutations in mitochondrial or nuclear DNA and inability of cells to cope with the consequences. The importance of MDF arises from its detection in the syndromes with defective DNA damage response (DDR) and cancer predisposition. Here, we will focus on the dual role of these syndromes in cancer predisposition and MDF with specific emphasis on impaired autophagy.
