DNA Strand Exchange Mediated by theEscherichiacoliRecA Protein Initiates in the Minor Groove of Double-Stranded DNA

Biochemistry ◽  
1997 ◽  
Vol 36 (15) ◽  
pp. 4650-4661 ◽  
Author(s):  
Xiaohua Zhou ◽  
Kenji Adzuma
Keyword(s):  
Minor Groove ◽  
Strand Exchange ◽  
Double Stranded Dna ◽  
Dna Strand Exchange ◽  
Dna Strand

scholarly journals Structure of a filament of stacked octamers of human DMC1 recombinase

2013 ◽  
Vol 69 (4) ◽  
pp. 382-386 ◽  
Author(s):  
Liqin Du ◽  
Yu Luo
Keyword(s):  
Electron Microscopy ◽  
Dna Sequences ◽  
Double Strand Breaks ◽  
Strand Exchange ◽  
Dna Double Strand Breaks ◽  
Strand Breaks ◽  
Double Stranded Dna ◽  
Dna Strand Exchange ◽  
Dna Strand ◽  
Remote Homologs

Eukaryal DMC1 proteins play a central role in homologous recombination in meiosis by assembling at the sites of programmed DNA double-strand breaks and carrying out a search for allelic DNA sequences located on homologous chromatids. They are close homologs of eukaryal Rad51 and archaeal RadA proteins and are remote homologs of bacterial RecA proteins. These recombinases (also called DNA strand-exchange proteins) promote a pivotal strand-exchange reaction between homologous single-stranded and double-stranded DNA substrates. An octameric form of a truncated human DMC1 devoid of its small N-terminal domain (residues 1–83) has been crystallized. The structure of the truncated DMC1 octamer is similar to that of the previously reported full-length DMC1 octamer, which has disordered N-terminal domains. In each protomer, only the ATP cap regions (Asp317–Glu323) show a noticeable conformational difference. The truncated DMC1 octamers further stack with alternate polarity into a filament. Similar filamentous assemblies of DMC1 have been observed to form on DNA by electron microscopy.

scholarly journals Swi5-Sfr1 protein stimulates Rad51-mediated DNA strand exchange reaction through organization of DNA bases in the presynaptic filament

2013 ◽  
Vol 42 (4) ◽  
pp. 2358-2365 ◽  
Author(s):  
Louise H. Fornander ◽  
Axelle Renodon-Cornière ◽  
Naoyuki Kuwabara ◽  
Kentaro Ito ◽  
Yasuhiro Tsutsui ◽  
...  
Keyword(s):  
Exchange Reaction ◽  
Linear Dichroism ◽  
Strand Exchange ◽  
Filament Axis ◽  
Double Stranded Dna ◽  
Dna Base ◽  
Dna Strand Exchange ◽  
Dna Strand ◽  
Base Orientation

Abstract The Swi5-Sfr1 heterodimer protein stimulates the Rad51-promoted DNA strand exchange reaction, a crucial step in homologous recombination. To clarify how this accessory protein acts on the strand exchange reaction, we have analyzed how the structure of the primary reaction intermediate, the Rad51/single-stranded DNA (ssDNA) complex filament formed in the presence of ATP, is affected by Swi5-Sfr1. Using flow linear dichroism spectroscopy, we observe that the nucleobases of the ssDNA are more perpendicularly aligned to the filament axis in the presence of Swi5-Sfr1, whereas the bases are more randomly oriented in the absence of Swi5-Sfr1. When using a modified version of the natural protein where the N-terminal part of Sfr1 is deleted, which has no affinity for DNA but maintained ability to stimulate the strand exchange reaction, we still observe the improved perpendicular DNA base orientation. This indicates that Swi5-Sfr1 exerts its activating effect through interaction with the Rad51 filament mainly and not with the DNA. We propose that the role of a coplanar alignment of nucleobases induced by Swi5-Sfr1 in the presynaptic Rad51/ssDNA complex is to facilitate the critical matching with an invading double-stranded DNA, hence stimulating the strand exchange reaction.

scholarly journals A novel pairing process promoted by Escherichia coli RecA protein: inverse DNA and RNA strand exchange

2000 ◽  
Vol 14 (6) ◽  
pp. 740-749
Author(s):  
Eugene N. Zaitsev ◽  
Stephen C. Kowalczykowski
Keyword(s):  
Escherichia Coli ◽  
Exchange Reaction ◽  
Reca Protein ◽  
Strand Exchange ◽  
Loop Formation ◽  
Dna And Rna ◽  
Double Stranded Dna ◽  
Dna Strand Exchange ◽  
Dna Strand ◽  
Recombination Reactions

Traditionally, recombination reactions promoted by RecA-like proteins initiate by forming a nucleoprotein filament on a single-stranded DNA (ssDNA), which then pairs with homologous double-stranded DNA (dsDNA). In this paper, we describe a novel pairing process that occurs in an unconventional manner: RecA protein polymerizes along dsDNA to form an active nucleoprotein filament that can pair and exchange strands with homologous ssDNA. Our results demonstrate that this “inverse” reaction is a unique, highly efficient DNA strand exchange reaction that is not due to redistribution of RecA protein from dsDNA to the homologous ssDNA partner. Finally, we demonstrate that the RecA protein–dsDNA filament can also pair and promote strand exchange with ssRNA. This inverse RNA strand exchange reaction is likely responsible for R-loop formation that is required for recombination-dependent DNA replication.

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