scholarly journals A postsynaptic role for single-stranded DNA-binding protein in recA protein-promoted DNA strand exchange.

1992 ◽  
Vol 267 (13) ◽  
pp. 9315-9320 ◽  
Author(s):  
P.E. Lavery ◽  
S.C. Kowalczykowski
Keyword(s):  
Dna Binding ◽  
Binding Protein ◽  
Reca Protein ◽  
Dna Binding Protein ◽  
Strand Exchange ◽  
Single Stranded Dna ◽  
Dna Strand Exchange ◽  
Dna Strand

scholarly journals Fission Yeast Rad51 and Dmc1, Two Efficient DNA Recombinases Forming Helical Nucleoprotein Filaments

2005 ◽  
Vol 25 (11) ◽  
pp. 4377-4387 ◽  
Author(s):  
Synthia Sauvageau ◽  
Alicja Z. Stasiak ◽  
Isabelle Banville ◽  
Mickaël Ploquin ◽  
Andrzej Stasiak ◽  
...  
Keyword(s):  
Reca Protein ◽  
Strand Break ◽  
Strand Exchange ◽  
Exchange Reactions ◽  
Single Stranded Dna ◽  
Strand Breaks ◽  
Lower Eukaryotes ◽  
Dna Double Strand Break ◽  
Dna Strand Exchange ◽  
Dna Strand

ABSTRACT Homologous recombination is important for the repair of double-strand breaks during meiosis. Eukaryotic cells require two homologs of Escherichia coli RecA protein, Rad51 and Dmc1, for meiotic recombination. To date, it is not clear, at the biochemical level, why two homologs of RecA are necessary during meiosis. To gain insight into this, we purified Schizosaccharomyces pombe Rad51 and Dmc1 to homogeneity. Purified Rad51 and Dmc1 form homo-oligomers, bind single-stranded DNA preferentially, and exhibit DNA-stimulated ATPase activity. Both Rad51 and Dmc1 promote the renaturation of complementary single-stranded DNA. Importantly, Rad51 and Dmc1 proteins catalyze ATP-dependent strand exchange reactions with homologous duplex DNA. Electron microscopy reveals that both S. pombe Rad51 and Dmc1 form nucleoprotein filaments. Rad51 formed helical nucleoprotein filaments on single-stranded DNA, whereas Dmc1 was found in two forms, as helical filaments and also as stacked rings. These results demonstrate that Rad51 and Dmc1 are both efficient recombinases in lower eukaryotes and reveal closer functional and structural similarities between the meiotic recombinase Dmc1 and Rad51. The DNA strand exchange activity of both Rad51 and Dmc1 is most likely critical for proper meiotic DNA double-strand break repair in lower eukaryotes.

scholarly journals Regulation of Deinococcus radiodurans RecA Protein Function via Modulation of Active and Inactive Nucleoprotein Filament States

2013 ◽  
Vol 288 (29) ◽  
pp. 21351-21366 ◽  
Author(s):  
Khanh V. Ngo ◽  
Eileen T. Molzberger ◽  
Sindhu Chitteni-Pattu ◽  
Michael M. Cox
Keyword(s):  
Dna Repair ◽  
Dna Binding ◽  
Protein Function ◽  
Deinococcus Radiodurans ◽  
Binding Protein ◽  
Reca Protein ◽  
Optimal Growth ◽  
Dna Binding Protein ◽  
Single Stranded Dna ◽  
Recombinational Dna Repair

The RecA protein of Deinococcus radiodurans (DrRecA) has a central role in genome reconstitution after exposure to extreme levels of ionizing radiation. When bound to DNA, filaments of DrRecA protein exhibit active and inactive states that are readily interconverted in response to several sets of stimuli and conditions. At 30 °C, the optimal growth temperature, and at physiological pH 7.5, DrRecA protein binds to double-stranded DNA (dsDNA) and forms extended helical filaments in the presence of ATP. However, the ATP is not hydrolyzed. ATP hydrolysis of the DrRecA-dsDNA filament is activated by addition of single-stranded DNA, with or without the single-stranded DNA-binding protein. The ATPase function of DrRecA nucleoprotein filaments thus exists in an inactive default state under some conditions. ATPase activity is thus not a reliable indicator of DNA binding for all bacterial RecA proteins. Activation is effected by situations in which the DNA substrates needed to initiate recombinational DNA repair are present. The inactive state can also be activated by decreasing the pH (protonation of multiple ionizable groups is required) or by addition of volume exclusion agents. Single-stranded DNA-binding protein plays a much more central role in DNA pairing and strand exchange catalyzed by DrRecA than is the case for the cognate proteins in Escherichia coli. The data suggest a mechanism to enhance the efficiency of recombinational DNA repair in the context of severe genomic degradation in D. radiodurans.

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