Functional similarities between phage Orf and Escherichia coli RecFOR in initiation of genetic exchange

Bowers, Laura and Reed, Patricia and Curtis, Fiona and Sharples, Gary (2006) Functional similarities between phage Orf and Escherichia coli RecFOR in initiation of genetic exchange. In: Society for General Microbiology 159th Meeting, 2006-09-112006-09-14.

Full text not available from this repository.


Genetic recombination in bacteriophage lambda relies on DNA end processing by Exo to expose 3’ tailed strands for annealing and exchange by Beta protein. Phage lambda encodes an additional recombinase, Orf, which participates in the early stages of recombination by supplying a function equivalent to the E. coli RecFOR complex. These host enzymes assist loading of the RecA strand exchange protein onto ssDNA coated with SSB. We have purified distantly-related Orf proteins from lambda and E. coli DLP12 prophage. Both Orf proteins bind DNA, favouring single-stranded over duplex and show no obvious preference for gapped, 3′or 5′tailed substrates. The crystal structure of lambda Orf reveals a homodimer arranged as a toroid with a shallow U-shaped cleft, lined with basic residues, running perpendicular to the central cavity. Gapped duplex DNA binding experiments suggest that DNA is accommodated on the surface cleft. Both Orf homologs appear to interact with E. coli SSB and we present evidence that they associate together on DNA. The functional similarities between Orf and RecFOR are discussed in relation to the early steps of recombinational exchange and the interplay between phage and bacterial recombinases.

Item Type:
Contribution to Conference (Poster)
Journal or Publication Title:
Society for General Microbiology 159th Meeting
Uncontrolled Keywords:
ID Code:
Deposited By:
Deposited On:
09 Dec 2011 13:10
Last Modified:
22 Nov 2022 13:46