Yang, L Naofumi Handa Liu, B Dillingham, Ms Wigley, Db Stephen Charles Kowalczykowski
Published in
Proceedings of the National Academy of Sciences
The RecBCD enzyme is a complex heterotrimeric helicase/nuclease that initiates recombination at double-stranded DNA breaks. In Escherichia coli, its activities are regulated by the octameric recombination hotspot, χ (5 -GCTGGTGG), which is read as a single-stranded DNA sequence while the enzyme is unwinding DNA at over ∼1,000 bp/s. Previous studies...
Hilario, Jovencio Amitani, Ichiro Baskin, Ronald J Kowalczykowski, Stephen C
Published in
Proceedings of the National Academy of Sciences of the United States of America
Rad51 protein (Rad51) is central to recombinational repair of double-strand DNA breaks. It polymerizes onto DNA and promotes strand exchange between homologous chromosomes. We visualized the real-time assembly and disassembly of human Rad51 nucleoprotein filaments on double-stranded DNA by single-molecule fluorescence microscopy. Rad51 assembly ext...
Martinez, Js Von Nicolai, C Taeho Kim Ehlén, Å Mazin, Av Stephen Charles Kowalczykowski Carreira, A
Published in
Proceedings of the National Academy of Sciences
In somatic cells, BRCA2 is needed for RAD51-mediated homologous recombination. The meiosis-specific DNA strand exchange protein, DMC1, promotes the formation of DNA strand invasion products (joint molecules) between homologous molecules in a fashion similar to RAD51. BRCA2 interacts directly with both human RAD51 and DMC1; in the case of RAD51, thi...
Carreira, A Stephen Charles Kowalczykowski
Published in
Proceedings of the National Academy of Sciences
The human tumor suppressor protein BRCA2 plays a key role in recombinational DNA repair. BRCA2 recruits RAD51 to sites of DNA damage through interaction with eight conserved motifs of approximately 35 amino acids, the BRC repeats; however, the specific function of each repeat remains unclear. Here, we investigated the function of the individual BRC...
Kantake, N Madiraju, Mv Sugiyama, T Stephen Charles Kowalczykowski
Published in
Proceedings of the National Academy of Sciences
We present biochemical evidence for the functional similarity of Escherichia coli RecO protein and bacteriophage T4 UvsY protein to eukaryotic Rad52 protein. Although Rad52 protein is conserved in eukaryotes, no sequence homologue has been found in prokaryotes or archeabacteria. Rad52 protein has two unique activities: facilitation of replication p...
Rad, B Stephen Charles Kowalczykowski
Published in
Proceedings of the National Academy of Sciences
Helicases are ubiquitous enzymes that unwind double-stranded DNA (dsDNA) to reveal single-stranded DNA (ssDNA) during essential processes such as replication, transcription, or repair. The Escherichia coli RecQ protein is a 3 to 5 helicase, which functions in the processes of homologous recombination and replication fork restart. Here, we analyze...
Mazin, Av Stephen Charles Kowalczykowski
Published in
Proceedings of the National Academy of Sciences
The RecA protein-single-stranded DNA (ssDNA) filament can bind a second DNA molecule. Binding of ssDNA to this secondary site shows specificity, in that polypyrimidinic DNA binds to the RecA protein-ssDNA filament with higher affinity than polypurinic sequences. The affinity of ssDNA, which is identical in sequence to that bound in the primary site...
Dixon, Da Churchill, Jj Stephen Charles Kowalczykowski
Published in
Proceedings of the National Academy of Sciences
Genetic recombination in Escherichia coli is stimulated by a RecBCD enzyme-mediated event at DNA sequences known as Chi (chi) sites (5 -GCTGGTGG-3 ). Previously, it was shown that chi acts to regulate the nuclease activity of RecBCD; here, we demonstrate that, under appropriate conditions, interaction with chi sites can also result in an inactivati...
Av, Nimonkar Az, Ozsoy J, Genschel P, Modrich Sc, Kowalczykowski
Published in
Proceedings of the National Academy of Sciences
The error-free repair of double-stranded DNA breaks by homologous recombination requires processing of broken ends. These processed ends are substrates for assembly of DNA strand exchange proteins that mediate DNA strand invasion. Here, we establish that human BLM helicase, a member of the RecQ family, stimulates the nucleolytic activity of human e...
Menetski, Jp Bear, Dg Stephen Charles Kowalczykowski
Published in
Proceedings of the National Academy of Sciences
A question remaining to be answered about RecA protein function concerns the role of ATP hydrolysis during the DNA-strand-exchange reaction. In this paper we describe the formation of joint molecules in the absence of ATP hydrolysis, using adenosine 5 -[gamma-thio]triphosphate (ATP[gamma S]) as nucleotide cofactor. Upon the addition of double-stran...
