Caught in the act: The lifetime of synaptic intermediates during the search for homology on DNA

Adam Mani, Ido Braslavsky, Rinat Arbel-Goren, Joel Stavans*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


Homologous recombination plays pivotal roles in DNA repair and in the generation of genetic diversity. To locate homologous target sequences at which strand exchange can occur within a timescale that a cell's biology demands, a single-stranded DNA-recombinase complex must search among a large number of sequences on a genome by forming synapses with chromosomal segments of DNA. A key element in the search is the time it takes for the two sequences of DNA to be compared, i.e. the synapse lifetime. Here, we visualize for the first time fluorescently tagged individual synapses formed by RecA, a prokaryotic recombinase, and measure their lifetime as a function of synapse length and differences in sequence between the participating DNAs. Surprisingly, lifetimes can be ~10 s long when the DNAs are fully heterologous, and much longer for partial homology, consistently with ensemble FRET measurements. Synapse lifetime increases rapidly as the length of a region of full homology at either the 3′-or5′-ends of the invading single-stranded DNA increases above 30 bases. A few mismatches can reduce dramatically the lifetime of synapses formed with nearly homologous DNAs. These results suggest the need for facilitated homology search mechanisms to locate homology successfully within the timescales observed in vivo.

Original languageAmerican English
Article numbergkp1177
Pages (from-to)2036-2043
Number of pages8
JournalNucleic Acids Research
Issue number6
StatePublished - 30 Dec 2009
Externally publishedYes


Dive into the research topics of 'Caught in the act: The lifetime of synaptic intermediates during the search for homology on DNA'. Together they form a unique fingerprint.

Cite this