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          Institute: MPI für molekulare Genetik     Collection: Department of Vertebrate Genomics     Display Documents

ID: 27783.0, MPI für molekulare Genetik / Department of Vertebrate Genomics
Characterization of Two Highly Similar Rad51 Homologs of Physcomitrella patens
Authors:Ayora, Silvia; Piruat, José I.; Luna, Rosa; Reiss, Bernd; Russo, Vincenzo E. A.; Aguilera, Andrés; Alonso, Juan C.
Date of Publication (YYYY-MM-DD):2002-02-08
Title of Journal:Journal of Molecular Biology
Journal Abbrev.:JMB
Issue / Number:1
Start Page:35
End Page:49
Review Status:not specified
Audience:Experts Only
Abstract / Description:The moss Physcomitrella patens, which is a land plant with efficient homologous recombination, encodes two Rad51 proteins (PpaRad51.1 and PpaRad51.2). The PpaRad51.1 and PpaRad51.2 proteins, which share 94 % identity between them, interact with themselves and with each other. Both proteins bind ssDNA and dsDNA in a Mg2+ and pH-dependent manner, with a stoichiometry of ~one PpaRad51.1 monomer per 3(±1) nt or bp and one PpaRad51.2 monomer per 1(±0.5) nt or bp, respectively. At neutral pH, a 1.6-fold excess of both proteins is required for ssDNA and dsDNA binding. PpaRad51.1 and PpaRad51.2 show ssDNA-dependent ATPase activity and efficiently promote strand annealing in a nucleotide-independent but in a Mg2+-dependent manner. Both proteins promote joint-molecule formation, DNA strand invasion and are able to catalyse strand exchange in the presence of Mg2+ and ATP. No further increase in the activities is observed when both proteins are present in the same reaction. None of the PpaRad51 gene products complement the DNA repair and recombination phenotype of Saccharomyces cerevisiaerad51 mutants. However, PpaRad51.1 confers a dominant-negative DNA repair phenotype, and both PpaRad51 proteins reduce the levels of double-strand break-induced recombination when overexpressed in S. cerevisiae wt cells. These results suggest that both PpaRad51 proteins are bona fide Rad51 proteins that may contribute, in a different manner, to homologous recombination, and that they might replace ScRad51 in a hypothetical yeast protein complex inactivating different functions required for recombinational repair.
Free Keywords:DNA recombination; DNA repair; RecA; ATPases; strand exchange
External Publication Status:published
Document Type:Article
Communicated by:Hans Lehrach
Affiliations:MPI für Pflanzenzüchtungsforschung
External Affiliations:Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Campus Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain.
Departamento de Biología Molecular, Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain.
Departamento de Genética, Universidad de Sevilla, 41012 Sevilla, Spain.
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