The role of AtMUS81 in DNA repair and its genetic interaction with the helicase AtRecQ4A

Abstract

The endonuclease MUS81 has been shown in a variety of organisms to be involved in DNA repair in mitotic and meiotic cells. Homologues of the MUS81 gene exist in the genomes of all eukaryotes, pointing to a conserved role of the protein. However, the biological role of MUS81 varies between different eukaryotes. For example, while loss of the gene results in strongly impaired fertility in Saccharomyces cerevisiae and nearly complete sterility in Schizosaccharomyces pombe, it is not essential for meiosis in mammals. We identified a functional homologue (AtMUS81/At4g30870) in the genome of Arabidopsis thaliana and isolated a full-length cDNA of this gene. Analysing two independent T-DNA insertion lines of AtMUS81, we found that they are sensitive to the mutagens MMS and MMC. Both mutants have a deficiency in homologous recombination in somatic cells but only after induction by genotoxic stress. In contrast to yeast, no meiotic defect of AtMUS81 mutants was detectable and the mutants are viable. Crosses with a hyperrecombinogenic mutant of the AtRecQ4A helicase resulted in synthetic lethality in the double mutant. Thus, the nuclease AtMUS81 and the helicase AtRecQ4A seem to be involved in two alternative pathways of resolution of replicative DNA structures in somatic cells.

The Fanconi Anemia Ortholog FANCM Ensures Ordered Homologous Recombination in Both Somatic and Meiotic Cells in Arabidopsis

“…In common with Sc-Sgs1, At-RECQ4A is related to the human BLM helicase (Hartung et al, 2007a). Analyses of At-RECQ4A in vegetative cells revealed functional similarity to Sc-Sgs1 (Hartung et al, 2006(Hartung et al, , 2007a(Hartung et al, , 2008. Surprisingly, however, this did not extend to their meiotic role.…”

“…A characteristic of these COs is that they exhibit interference, whereby the position of one CO decreases the probability of a second in an adjacent chromosomal region (Jones, 1984). A proportion of COs arises via a ZMM-independent process that appears to involve the structure-specific endonuclease At-MUS81 (for MMS and UV sensitive81) (Hartung et al, 2006;Geuting et al, 2009). These COs are interference insensitive, exhibit a random numerical distribution, and amount to ;15% of the total in the wild type (Higgins et al, 2008a).…”

The Structure-Specific Endonucleases MUS81 and SEND1 Are Essential for Telomere Stability in Arabidopsis

“…In Arabidopsis, MUS81 has been shown to cleave HJ in vitro (Geuting et al, 2009) and to act in HR, DNA repair, and processing of aberrant replication intermediates (Hartung et al, 2006(Hartung et al, , 2007Mannuss et al, 2010). No SLX1-SLX4 complex has been characterized in plants, and although homologs of GEN1 have been identified, their function in planta has not been clarified.…”

The translesion polymerase ζ has roles dependent and independent of the nuclease MUS81 and the helicase RECQ4A in DNA damage repair in Arabidopsis

“…We previously showed that mus81 transfer DNA (T-DNA) insertion lines in Arabidopsis are highly sensitive to treatment with MMS, cisplatin, hydroxyurea, ionizing irradiation, and MMC. We also found that AtMUS81 can form a complex with its heterologous binding partners AtEME1A or AtEME1B that is able to process intricate DNA structures, such as nicked Holliday junctions, which might also form at stalled replication forks (Hartung et al, 2006;Geuting et al, 2009). …”

“…For rev3-5, wild-type PCR was performed using the gene-specific primers SK-75 (59-GCCCTGA-AGCCTTCCTTACTTG-39) and SK-76 (59-GAAGAGGCTAGTTCAAACGTCC-39); for identification of T-DNA insertions, SK-75 was combined with the T-DNA-specific primer Lbd1 (59-TCGGAACCACCATCAAACAG-39). The lines mus81-1, recq4A-4, and atr-2 were genotyped as previously described (Culligan et al, 2004;Hartung et al, 2006).…”