PMID:22912580

Citation	Schumacher, AJ, Mohni, KN, Kan, Y, Hendrickson, EA, Stark, JM and Weller, SK (2012) The HSV-1 Exonuclease, UL12, Stimulates Recombination by a Single Strand Annealing Mechanism. PLoS Pathog. 8:e1002862
Abstract	Production of concatemeric DNA is an essential step during HSV infection, as the packaging machinery must recognize longer-than-unit-length concatemers; however, the mechanism by which they are formed is poorly understood. Although it has been proposed that the viral genome circularizes and rolling circle replication leads to the formation of concatemers, several lines of evidence suggest that HSV DNA replication involves recombination-dependent replication reminiscent of bacteriophages λ and T4. Similar to λ, HSV-1 encodes a 5'-to-3' exonuclease (UL12) and a single strand annealing protein [SSAP (ICP8)] that interact with each other and can perform strand exchange in vitro. By analogy with λ phage, HSV may utilize viral and/or cellular recombination proteins during DNA replication. At least four double strand break repair pathways are present in eukaryotic cells, and HSV-1 is known to manipulate several components of these pathways. Chromosomally integrated reporter assays were used to measure the repair of double strand breaks in HSV-infected cells. Single strand annealing (SSA) was increased in HSV-infected cells, while homologous recombination (HR), non-homologous end joining (NHEJ) and alternative non-homologous end joining (A-NHEJ) were decreased. The increase in SSA was abolished when cells were infected with a viral mutant lacking UL12. Moreover, expression of UL12 alone caused an increase in SSA, which was completely eliminated when a UL12 mutant lacking exonuclease activity was expressed. UL12-mediated stimulation of SSA was decreased in cells lacking the cellular SSAP, Rad52, and could be restored by coexpressing the viral SSAP, ICP8, indicating that an SSAP is also required. These results demonstrate that UL12 can specifically stimulate SSA and that either ICP8 or Rad52 can function as an SSAP. We suggest that SSA is the homology-mediated repair pathway utilized during HSV infection.
Links	PubMed PMC3415443 Online version:10.1371/journal.ppat.1002862
Keywords
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
MOUSE:RAD52		GO:0010792: DNA double-strand break processing involved in repair via single-strand annealing	ECO:0000315:		P		Refer to Fig. 6	complete CACAO 5414
MOUSE:RAD52	involved_in	GO:0010792: DNA double-strand break processing involved in repair via single-strand annealing	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete
HHV1K:DNBI		GO:0010792: DNA double-strand break processing involved in repair via single-strand annealing	ECO:0000315:		P		Refer to Fig. 6	complete CACAO 5413
HHV1K:DNBI	involved_in	GO:0010792: DNA double-strand break processing involved in repair via single-strand annealing	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete
HHV1:Q68978		GO:0010792: DNA double-strand break processing involved in repair via single-strand annealing	ECO:0000314:		P		Refer to Fig. 5	complete CACAO 5415
HHV1:Q68978	involved_in	GO:0010792: DNA double-strand break processing involved in repair via single-strand annealing	ECO:0000314: direct assay evidence used in manual assertion		P		Seeded From UniProt	complete

References

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