Three Phases in Homologous Pairing: Polymerization of recA Protein on Single-stranded DNA, Synapsis, and Polar Strand Exchange

Radding, Charles M.; Flory, J; Wu, Anna M.; Kahn, Roger; Dasgupta, Chandan; Gonda, David K.; Bianchi, Marco; Tsang, Siu Sing

doi:10.1101/sqb.1983.047.01.094

Cited by 57 publications

(24 citation statements)

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“…The sigma and alpha forms were more predominant in reactions that were incubated for a short time, while the gapped circle form ( Figure 2F) was the most common form found upon extended incubation ( Table 1). The identification of these forms, which are characteristic of classic strand exchange reactions, [41][42][43] demonstrates that UL12/ ICP8 produces the same products as bona fide recombinases and supports our previous suggestion that this two-enzyme complex functions as such in infected cells. 23 …”

Section: Em Visualization Of the Intermediates And Products In A Ul12supporting

confidence: 76%

Catalysis of Strand Exchange by the HSV-1 UL12 and ICP8 Proteins: Potent ICP8 Recombinase Activity is Revealed upon Resection of dsDNA Substrate by Nuclease

Reuven

Willcox

Griffith

et al. 2004

Journal of Molecular Biology

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The replication of herpes simplex virus type 1 (HSV-1) is associated with a high degree of homologous recombination, which is likely to be mediated, in part, by HSV-1-encoded proteins. We have previously shown that the HSV-1 encoded ICP8 protein and alkaline nuclease UL12 are capable of catalyzing an in vitro strand-exchange reaction. Here, we show, by electron microscopy, that the products of the strand exchange reaction between linear double-stranded DNA and circular single-stranded DNA consist of the expected joint molecule forms: sigma, alpha, and gapped circles. Other exonucleases, such as lambda Red α, which, like UL12, digests 5′-3′, as well as Escherichia coli exonuclease III (ExoIII), which digests 3′-5′, could substitute for UL12 in the strand exchange reaction by providing a resected DNA end. ICP8 generated the same intermediates and strand exchange products when the double-stranded DNA substrate was preresected by any of the nucleases. Using substrates with large regions of non-homology we found that pairing by ICP8 could be initiated from the middle of a DNA molecule and did not require a homologous end. In this reaction, the resection of a DNA end by the nuclease is required to reveal homologous sequences capable of being paired by ICP8. This study further illustrates the complexity of the multi-functional ICP8 protein.

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Section: Em Visualization Of the Intermediates And Products In A Ul12supporting

confidence: 76%

Catalysis of Strand Exchange by the HSV-1 UL12 and ICP8 Proteins: Potent ICP8 Recombinase Activity is Revealed upon Resection of dsDNA Substrate by Nuclease

Reuven

Willcox

Griffith

et al. 2004

Journal of Molecular Biology

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“…A variation of single-strand break repair models for gene conversion (Meselson and Radding 1975;Radding et al 1982) could account for the apparent polarity of IgL gene conversion we have observed. As shown in Figure 6, a single-stranded break in the nontranscribed strand of the rearranged VL1 gene may initiate gene conversion during transcription.…”

Section: Discussionmentioning

confidence: 92%

Chicken IgL variable region gene conversions display pseudogene donor preference and 5' to 3' polarity.

McCormack¹,

Thompson²

1990

Genes Dev.

111

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Chicken immunoglobulin variable region diversity is generated during B-cell development in the bursa of Fabricius by intrachromosomal gene conversion, resulting in the replacement of sequence blocks within the unique rearranged Vu and Vm genes with homologous sequences derived from V region pseudogene segments (lgV1. In this report, the nucleotide sequences of 217 gene conversion events in 52 random IgL clones were analyzed to characterize the molecular mechanism of gene conversion. The frequency of ~V, usage as gene conversion donors is shown to depend on the proximity of the ~gVr segment to Vr~, extent of homology with V~I, and relative orientation of the ~gVL segments. Gene conversion events are not observed in the 5' region of homology between yVL segments and Vu, but are distributed throughout the remainder of the V~ exon. The 5' ends of individual gene conversion events always begin in regions of homology between the donor ~gVL and recipient VL~ gene, whereas the 3' ends can occur in regions of nonhomology and often have nucleotide insertions or deletions. These results suggest a 5' to 3' polarity in the gene conversion mechanism. The implications of our data are discussed in relation to current molecular models of gene conversion.

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“…In contrast, the somatic gene conversion of the rearranged IgL V gene segment appears to occur exclusively in cis and fails to demonstrate a significant rate of recombination between alleles. Although several existing models of gene conversion have been suggested that can account for all of the features of meiotic gene conversion (Radding et al 1982;Szostak et al 19831, it is not yet clear how the more specific and developmentally regulated characteristics of immunoglobulin gene conversion can be determined by existing models of gene conversion. To this purpose, studies in the accompanying manuscript (McCormack and Thompson 1990) have been performed to characterize more completely the individual gene conversions observed within the avian system.…”

Section: Discussionmentioning

confidence: 99%

Templated insertions in the rearranged chicken IgL V gene segment arise by intrachromosomal gene conversion.

Carlson¹,

McCormack²,

Postema³

et al. 1990

Genes Dev.

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Three Phases in Homologous Pairing: Polymerization of recA Protein on Single-stranded DNA, Synapsis, and Polar Strand Exchange

Cited by 57 publications

References 0 publications

Catalysis of Strand Exchange by the HSV-1 UL12 and ICP8 Proteins: Potent ICP8 Recombinase Activity is Revealed upon Resection of dsDNA Substrate by Nuclease

Catalysis of Strand Exchange by the HSV-1 UL12 and ICP8 Proteins: Potent ICP8 Recombinase Activity is Revealed upon Resection of dsDNA Substrate by Nuclease

Chicken IgL variable region gene conversions display pseudogene donor preference and 5' to 3' polarity.

Templated insertions in the rearranged chicken IgL V gene segment arise by intrachromosomal gene conversion.

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