In contrast to yeast, however, phosphorylation does not directly activate the nuclease activity of the enzyme but promotes an interaction between MUS81-EME1 and a second structure-selective nuclease SLX1-SLX4 ( 9). Similarly, in human cells, phosphorylation of EME1 by CDK, and to a lesser extent by PLK1, correlates with increased MUS81-EME1 nuclease activity at prometaphase ( 9, 28). cerevisiae Mms4 is phosphorylated in a cell cycle-dependent manner by the cyclin-dependent kinase Cdk and the Polo-like kinase Cdc5 leading to a stimulation of Mus81-Mms4 activity ( 28–31). Recombinant human MUS81-EME1 exhibits similar substrate specificities ( 9, 26, 27). In contrast, intact HJs are cleaved with a relatively low efficiency. Purified recombinant Mus81-Eme1 and Mus81-Mms4 proteins are active on a range of DNA substrates including 3′-flaps, replication forks and nicked Holliday junctions (HJs), which they cleave by the introduction of a nick close to the branch point ( 22–25). Similarly, Mus81-deficient mice exhibit defects in the repair of meiotic double strand breaks and reduced numbers of mature epididymal sperm ( 21). In addition to the mitotic functions, MUS81 is important for meiosis: for example, in yeast, Mus81-Eme1 ( Schizosaccharomyces pombe) and Mus81-Mms4 ( S acch a romyces cerevisiae) are required for the resolution of meiotic recombination intermediates ( 15–20). MUS81 is also required for telomere maintenance in cells that use an Alternative Lengthening of Telomeres (ALT) telomerase-independent mechanism for telomere maintenance ( 14). In both yeast and mammalian cells, loss of MUS81 activity leads to a hypersensitivity to replication fork-stalling agents such as cisplatin, camptothecin or hydroxyurea ( 2, 3, 12, 13). MUS81 is the catalytic subunit of the MUS81-EME1 structure-selective endonuclease that plays important roles in DNA repair, including (i) the repair of interstrand cross-links ( 3), (ii) the repair and restart of stalled replication forks ( 4–7) and (iii) the resolution of recombination intermediates ( 8–11). The MUS81 protein is required for the maintenance of genomic stability, and its loss has been associated with cancer development ( 1, 2). These studies suggest that MUS81-EME1 and MUS81-EME2 exhibit similar and yet distinct DNA structure selectivity, indicating that the two MUS81 complexes may promote different nucleolytic cleavage reactions in vivo. Additionally, MUS81-EME2 acts on 5′-flap structures to cleave off a duplex arm, in reactions that cannot be promoted by MUS81-EME1. In contrast to MUS81-EME1, however, MUS81-EME2 cuts D-loop recombination intermediates and in so doing disengages the D-loop structure by cleaving the 3′-invading strand. Like MUS81-EME1, MUS81-EME2 cleaves 3′-flaps, replication forks and nicked Holliday junctions, and exhibits limited endonuclease activity with intact Holliday junctions. We find that MUS81-EME2 is a more active endonuclease than MUS81-EME1 and exhibits broader substrate specificity. Here, we have purified MUS81-EME2 and compared its activities with MUS81-EME1. Little is presently known about the activities of MUS81-EME2. Although the actions of MUS81-EME1 have been extensively investigated, MUS81 is the catalytic subunit of two human structure-selective endonucleases, MUS81-EME1 and MUS81-EME2. $z$~6 quasar host galaxies.MUS81 plays important cellular roles in the restart of stalled replication forks, the resolution of recombination intermediates and in telomere length maintenance. Reservoirs of molecular gas fueling star formation and nuclear accretion in Our analysis reiterates the presence of massive With a modified black body spectrum with a dust temperature $T_$, exposed to a radiation field with intensity The 3mm to 1mm flux density ratios are consistent Significance in all the targeted sources, thus doubling the number of suchĭetections in z~6 quasars. Infra-red-luminous quasars that have been previously studied in their 1mm dustĬontinuum and line emission. We target the 3mm dustĬontinuum, and the line emission from CO(6-5), CO(7-6), 2-1 in 10 The IRAM / Northern Extended Millimeter Array. Riechers, Bade Uzgil, Feige Wang, Ran Wang, Axel Weiss, Jan Martin Winters, Jinyi Yang Download PDF Abstract: We investigate the molecular gas content of z~6 quasar host galaxies using Groves, Jianan Li, Chiara Mazzucchelli, Roberto Neri, Dominik A. Carilli, Pierre Cox, Xiaohui Fan, Emanuele Paolo Farina, Carl Ferkinhoff, Brent A. Authors: Roberto Decarli, Antonio Pensabene, Bram Venemans, Fabian Walter, Eduardo Banados, Frank Bertoldi, Chris L.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |