title: Induction of direct repeat recombination by psoralen-DNA adducts in Saccharomyces cerevisiae: defects in DNA repair increase gene copy number variation.
abstract: Psoralen photoreaction produces covalent monoadducts and interstrand crosslinks in DNA. The interstrand DNA crosslinks are complex double strand lesions that require the involvement of multiple pathways for repair. Homologous recombination, which can carry out error-free repair, is a major pathway for crosslink repair; however, some recombination pathways can also produce DNA rearrangements. Psoralen photoreaction-induced recombination in yeast was measured using direct repeat substrates that can detect gene conversions, a form of conservative recombination, as well as deletions and triplications, which generate gene copy number changes. In repair-proficient cells the major products of recombination were gene conversions, along with substantial fractions of deletions. Deficiencies in DNA repair pathways increased non-conservative recombination products. Homologous recombination-deficient rad51, rad54, and rad57 strains had low levels of crosslink-induced recombination, and most products were deletions produced by single strand annealing. Nucleotide excision repair-deficient rad1 and rad2 yeast had increased levels of triplications, and rad1 cells had lower crosslink-induced recombination. Deficiencies in post-replication repair increased crosslink-induced recombination and gene copy number changes. Loss of REV3 function, in the error-prone branch, and of RAD5 and UBC13, in the error-free branch, produced moderate increases in deletions and triplications; rad18 cells, deficient in both post-replication repair sub-pathways, exhibited hyperrecombination, with primarily non-conservative products. Proper functioning of all the DNA repair pathways tested was required to maintain genomic stability and avoid gene copy number variation in response to interstrand crosslinks.
authors: Queens College, City University of New York, Department of Chemistry and Biochemistry, 65-30 Kissena Boulevard, Queens, NY 11367, USA. Electronic address: Wilma.Saffran@qc.cuny.edu.
authors: Wilma A
authors: WA
authors: Saffran
authors: Queens College, City University of New York, Department of Chemistry and Biochemistry, 65-30 Kissena Boulevard, Queens, NY 11367, USA.
authors: Anam
authors: A
authors: Ahmed
authors: Queens College, City University of New York, Department of Chemistry and Biochemistry, 65-30 Kissena Boulevard, Queens, NY 11367, USA.
authors: Olga
authors: O
authors: Binyaminov
authors: Queens College, City University of New York, Department of Chemistry and Biochemistry, 65-30 Kissena Boulevard, Queens, NY 11367, USA.
authors: Cynthia
authors: C
authors: Gonzalez
authors: Queens College, City University of New York, Department of Chemistry and Biochemistry, 65-30 Kissena Boulevard, Queens, NY 11367, USA.
authors: Amita
authors: A
authors: Gupta
authors: Queens College, City University of New York, Department of Chemistry and Biochemistry, 65-30 Kissena Boulevard, Queens, NY 11367, USA.
authors: Manuel A
authors: MA
authors: Fajardo
authors: Queens College, City University of New York, Department of Chemistry and Biochemistry, 65-30 Kissena Boulevard, Queens, NY 11367, USA.
authors: Devindra
authors: D
authors: Kishun
authors: Queens College, City University of New York, Department of Chemistry and Biochemistry, 65-30 Kissena Boulevard, Queens, NY 11367, USA.
authors: Ashana
authors: A
authors: Nandram
authors: Queens College, City University of New York, Department of Chemistry and Biochemistry, 65-30 Kissena Boulevard, Queens, NY 11367, USA.
authors: Kenneth
authors: K
authors: Reyes
authors: Queens College, City University of New York, Department of Chemistry and Biochemistry, 65-30 Kissena Boulevard, Queens, NY 11367, USA.
authors: Karina
authors: K
authors: Scalercio
authors: Queens College, City University of New York, Department of Chemistry and Biochemistry, 65-30 Kissena Boulevard, Queens, NY 11367, USA.
authors: Charles W
authors: CW
authors: Senior
mesh_terms: D018736:DNA Adducts / Q000235:genetics*; D056915:DNA Copy Number Variations; D045643:DNA Repair Enzymes / Q000235:genetics / Q000378:metabolism; D011564:Furocoumarins / Q000235:genetics*; D059767:Recombinational DNA Repair; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism
chemical_list: D018736:DNA Adducts; D011564:Furocoumarins; C056465:psoralen-DNA adduct; D045643:DNA Repair Enzymes
keywords: Gene copy number variation; Homologous recombination; Interstrand crosslinks; Nucleotide excision repair; Post-replication repair