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Protein FULL name:
Crossover junction endonuclease MUS81, MMS and UV-sensitive protein 81
Mus81p (Saccharomyces cerevisiae) is product of expression of MUS81 gene.
Mus81p is involved in:
HRR in Saccharomyces cerevisiae
FUNCTION: Interacts with MMS4 to form a DNA structure-specific endonuclease with substrate preference for branched DNA structures with a 5'-end at the branch nick. Typical substrates include 3'- flap structures, D-loops, replication forks with regressed leading strands and nicked Holliday junctions. Cleavage probably occurs approximately half a helical turn upstream of the free 5'-end in these structures. May be required in mitosis for the processing of stalled replication fork intermediates arising spontaneously or subsequent to treatment with DNA damaging agents such as methylmethane sulfonate (MMS), camptothecin (CPT) or UV. May be required in meiosis for the repair of meiosis-specific double strand breaks subsequent to single-end invasion (SEI). This involves consecutive cleavage of D-loops and nicked Holliday junctions leading to sister chromatid crossover. In contrast to MSH4-MSH5 dependent crossover, double Holliday junctions do not seem to be involved. Spore formation and viability are severely impaired in deletion strains.
COFACTOR: Magnesium or manganese.
BIOPHYSICOCHEMICAL PROPERTIES: Kinetic parameters: KM=31.1 nM for a nicked Holliday junction; KM=6.84 nM for a regressed leading strand replication fork; KM=4.8 nM for for a 3'-flap structure; KM=3.45 nM for a nicked duplex; KM=14.0 nM for a regressed lagging strand replication fork; KM=245 nM for a Y structure; KM=173 nM for a double flap structure; Vmax=55.6 nmol/min/ng enzyme with a nicked Holliday junction as substrate; Vmax=31.3 nmol/min/ng enzyme with a regressed leading strand replication fork as substrate; Vmax=24.4 nmol/min/ng enzyme with a 3'-flap structure as substrate; Vmax=2.21 nmol/min/ng enzyme with a nicked duplex as substrate; Vmax=0.832 nmol/min/ng enzyme with a regressed lagging strand replication fork as subsystrate; Vmax=0.0468 nmol/min/ng enzyme with a Y structure as substrate; Vmax=0.0879 nmol/min/ng enzyme with a double flap structure as substrate; pH dependence: Optimum pH is 8.0 for the cleavage of a 3'-flap structure;
SUBUNIT: Interacts with MMS4 and RAD54.
INTERACTION: P38257:MMS4; NbExp=1; IntAct=EBI-33508, EBI-21547;
SUBCELLULAR LOCATION: Nucleus.
MISCELLANEOUS: Two distinct classes of meiotic crossovers have been demonstrated in budding yeast. Class I crossovers exhibit crossover interference and require MSH4 and MSH5 for their resolution, while class II crossovers exhibit no crossover interference and require MUS81 and MMS4. While class I crossovers represent the majority of crossovers in S.cerevisiae, they are virtually absent in S.pombe, which lacks orthologs of MSH4 and MSH5.
MISCELLANEOUS: Present with 300 molecules/cell in log phase SD medium.
SIMILARITY: Belongs to the XPF family.
SIMILARITY: Contains 1 ERCC4 domain.
Links to other databases:
Mus81p (Saccharomyces cerevisiae) is able to recognize following damages:
Mus81p (Saccharomyces cerevisiae) belongs to following protein families:
Last modification of this entry: Oct. 13, 2010.
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