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Cell cycle and genetic requirements of two pathways of nonhomologous end-joining repair of double-strand breaks in Saccharomyces cerevisiae.
Mol Cell Biol. 1996 May; 16(5):2164-73.MC

Abstract

In Saccharomyces cerevisiae, an HO endonuclease-induced double-strand break can be repaired by at least two pathways of nonhomologous end joining (NHEJ) that closely resemble events in mammalian cells. In one pathway the chromosome ends are degraded to yield deletions with different sizes whose endpoints have 1 to 6 bp of homology. Alternatively, the 4-bp overhanging 3' ends of HO-cut DNA (5'-AACA-3') are not degraded but can be base paired in misalignment to produce +CA and +ACA insertions. When HO was expressed throughout the cell cycle, the efficiency of NHEJ repair was 30 times higher than when HO was expressed only in G1. The types of repair events were also very different when HO was expressed throughout the cell cycle; 78% of survivors had small insertions, while almost none had large deletions. When HO expression was confined to the G1 phase, only 21% were insertions and 38% had large deletions. These results suggest that there are distinct mechanisms of NHEJ repair producing either insertions or deletions and that these two pathways are differently affected by the time in the cell cycle when HO is expressed. The frequency of NHEJ is unaltered in strains from which RAD1, RAD2, RAD51, RAD52, RAD54, or RAD57 is deleted; however, deletions of RAD50, XRS2, or MRE11 reduced NHEJ by more than 70-fold when HO was not cell cycle regulated. Moreover, mutations in these three genes markedly reduced +CA insertions, while significantly increasing the proportion of both small (-ACA) and larger deletion events. In contrast, the rad5O mutation had little effect on the viability of G1-induced cells but significantly reduced the frequency of both +CA insertions and -ACA deletions in favor of larger deletions. Thus, RAD50 (and by extension XRS2 and MRE11) exerts a much more important role in the insertion-producing pathway of NHEJ repair found in S and/or G2 than in the less frequent deletion events that predominate when HO is expressed only in G1.

Authors+Show Affiliations

Rosenstiel Center and Department of Biology, Brandeis University, Waltham, Massachusetts 02254-09110, USA.No affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

8628283

Citation

Moore, J K., and J E. Haber. "Cell Cycle and Genetic Requirements of Two Pathways of Nonhomologous End-joining Repair of Double-strand Breaks in Saccharomyces Cerevisiae." Molecular and Cellular Biology, vol. 16, no. 5, 1996, pp. 2164-73.
Moore JK, Haber JE. Cell cycle and genetic requirements of two pathways of nonhomologous end-joining repair of double-strand breaks in Saccharomyces cerevisiae. Mol Cell Biol. 1996;16(5):2164-73.
Moore, J. K., & Haber, J. E. (1996). Cell cycle and genetic requirements of two pathways of nonhomologous end-joining repair of double-strand breaks in Saccharomyces cerevisiae. Molecular and Cellular Biology, 16(5), 2164-73.
Moore JK, Haber JE. Cell Cycle and Genetic Requirements of Two Pathways of Nonhomologous End-joining Repair of Double-strand Breaks in Saccharomyces Cerevisiae. Mol Cell Biol. 1996;16(5):2164-73. PubMed PMID: 8628283.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Cell cycle and genetic requirements of two pathways of nonhomologous end-joining repair of double-strand breaks in Saccharomyces cerevisiae. AU - Moore,J K, AU - Haber,J E, PY - 1996/5/1/pubmed PY - 1996/5/1/medline PY - 1996/5/1/entrez SP - 2164 EP - 73 JF - Molecular and cellular biology JO - Mol Cell Biol VL - 16 IS - 5 N2 - In Saccharomyces cerevisiae, an HO endonuclease-induced double-strand break can be repaired by at least two pathways of nonhomologous end joining (NHEJ) that closely resemble events in mammalian cells. In one pathway the chromosome ends are degraded to yield deletions with different sizes whose endpoints have 1 to 6 bp of homology. Alternatively, the 4-bp overhanging 3' ends of HO-cut DNA (5'-AACA-3') are not degraded but can be base paired in misalignment to produce +CA and +ACA insertions. When HO was expressed throughout the cell cycle, the efficiency of NHEJ repair was 30 times higher than when HO was expressed only in G1. The types of repair events were also very different when HO was expressed throughout the cell cycle; 78% of survivors had small insertions, while almost none had large deletions. When HO expression was confined to the G1 phase, only 21% were insertions and 38% had large deletions. These results suggest that there are distinct mechanisms of NHEJ repair producing either insertions or deletions and that these two pathways are differently affected by the time in the cell cycle when HO is expressed. The frequency of NHEJ is unaltered in strains from which RAD1, RAD2, RAD51, RAD52, RAD54, or RAD57 is deleted; however, deletions of RAD50, XRS2, or MRE11 reduced NHEJ by more than 70-fold when HO was not cell cycle regulated. Moreover, mutations in these three genes markedly reduced +CA insertions, while significantly increasing the proportion of both small (-ACA) and larger deletion events. In contrast, the rad5O mutation had little effect on the viability of G1-induced cells but significantly reduced the frequency of both +CA insertions and -ACA deletions in favor of larger deletions. Thus, RAD50 (and by extension XRS2 and MRE11) exerts a much more important role in the insertion-producing pathway of NHEJ repair found in S and/or G2 than in the less frequent deletion events that predominate when HO is expressed only in G1. SN - 0270-7306 UR - https://www.unboundmedicine.com/medline/citation/8628283/Cell_cycle_and_genetic_requirements_of_two_pathways_of_nonhomologous_end_joining_repair_of_double_strand_breaks_in_Saccharomyces_cerevisiae_ L2 - https://journals.asm.org/doi/10.1128/MCB.16.5.2164?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -