Journal ArticleDOI
DNA helicase Srs2 disrupts the Rad51 presynaptic filament
Lumir Krejci,Stephen Van Komen,Ying Li,Jana Villemain,Mothe Sreedhar Reddy,Hannah L. Klein,Thomas E. Ellenberger,Patrick Sung +7 more
TLDR
The role of SRS2 in recombination modulation is clarified by purifying its encoded product and examining its interactions with the Rad51 recombinase, and it is shown that Srs2 acts by dislodging Rad51 from ssDNA.Abstract:
Mutations in the Saccharomyces cerevisiae gene SRS2 result in the yeast's sensitivity to genotoxic agents, failure to recover or adapt from DNA damage checkpoint-mediated cell cycle arrest, slow growth, chromosome loss, and hyper-recombination1,2. Furthermore, double mutant strains, with mutations in DNA helicase genes SRS2 and SGS1, show low viability that can be overcome by inactivating recombination, implying that untimely recombination is the cause of growth impairment1,3,4. Here we clarify the role of SRS2 in recombination modulation by purifying its encoded product and examining its interactions with the Rad51 recombinase. Srs2 has a robust ATPase activity that is dependent on single-stranded DNA (ssDNA) and binds Rad51, but the addition of a catalytic quantity of Srs2 to Rad51-mediated recombination reactions causes severe inhibition of these reactions. We show that Srs2 acts by dislodging Rad51 from ssDNA. Thus, the attenuation of recombination efficiency by Srs2 stems primarily from its ability to dismantle the Rad51 presynaptic filament efficiently. Our findings have implications for the basis of Bloom's and Werner's syndromes, which are caused by mutations in DNA helicases and are characterized by increased frequencies of recombination and a predisposition to cancers and accelerated ageing5.read more
Citations
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Bmi-1 is required for maintenance of adult self-renewing haematopoietic stem cells.
In-Kyung Park,Dalong Qian,Mark J. Kiel,Michael W. Becker,Michael Pihalja,Irving L. Weissman,Sean J. Morrison,Sean J. Morrison,Michael F. Clarke +8 more
TL;DR: The results indicate that Bmi-1 is essential for the generation of self-renewing adult HSCs, which are required for haematopoiesis to persist for the lifetime of the animal.
Journal ArticleDOI
Regulation of DNA repair throughout the cell cycle
Dana Branzei,Marco Foiani +1 more
TL;DR: The repair of DNA lesions that occur endogenously or in response to diverse genotoxic stresses is indispensable for genome integrity and has provided insights into the mechanisms that contribute to DNA repair in specific cell-cycle phases.
Journal ArticleDOI
Repair Pathway Choices and Consequences at the Double-Strand Break
TL;DR: Alternative error-prone DSB repair pathways, namely alternative end joining (alt-EJ) and single-strand annealing (SSA) have been recently shown to operate in many different conditions and to contribute to genome rearrangements and oncogenic transformation.
Journal ArticleDOI
Eukaryotic translesion synthesis DNA polymerases: Specificity of structure and function
TL;DR: This review focuses on eukaryotic translesion synthesis (TLS) DNA polymerases, and the emphasis is on Saccharomyces cerevisiae and human Y- family polymerases (Pols) eta, iota, kappa, and Rev1, as well as on Polzeta, which is a member of the B-family polymerases.
Journal ArticleDOI
Regulation of homologous recombination in eukaryotes
TL;DR: The factors and mechanistic stages of recombination that are subject to regulation are reviewed and it is suggested that recombination achieves flexibility and robustness by proceeding through metastable, reversible intermediates.
References
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Journal ArticleDOI
Alternative reading frames of the INK4a tumor suppressor gene encode two unrelated proteins capable of inducing cell cycle arrest
TL;DR: The INK4a gene encodes an inhibitor of the cyclin D-dependent kinases CDK4 and CDK6 that blocks them from phosphorylating the retinoblastoma protein and prevents exit from the G1 phase of the cell cycle.
Journal ArticleDOI
Bmi-1 determines the proliferative capacity of normal and leukaemic stem cells
Julie Lessard,Guy Sauvageau +1 more
TL;DR: Evidence is provided that the proliferative potential of leukaemic stem and progenitor cells lacking Bmi-1 is compromised because they eventually undergo proliferation arrest and show signs of differentiation and apoptosis, leading to transplant failure of the leukaemia.
Journal ArticleDOI
Catalysis of ATP-dependent homologous DNA pairing and strand exchange by yeast RAD51 protein
TL;DR: The RAD51 gene of Saccharomyces cerevisiae is required for genetic recombination and DNA double-strand break repair and it is demonstrated that RAD51 protein pairs circular viral single-stranded DNA from phi X 174 or M13 with its respective homologous linear double-Stranded form, indicating that RAD 51 can catalyze strand exchange.
Journal ArticleDOI
Flk-2 is a marker in hematopoietic stem cell differentiation: A simple method to isolate long-term stem cells
TL;DR: To establish whether the Flk-2/Flt3 receptor tyrosine kinase was expressed on the most primitive LT-HSCs, highly purified multipotent stem and progenitor cells were sorted and used in competitive reconstitution assays.
Journal ArticleDOI
The T Cell Leukemia Oncoprotein SCL/tal-1 Is Essential for Development of All Hematopoietic Lineages
Catherine Porcher,Wojciech Swat,Wojciech Swat,Karen Rockwell,Yuko Fujiwara,Yuko Fujiwara,Frederick W. Alt,Frederick W. Alt,Stuart H. Orkin,Stuart H. Orkin +9 more
TL;DR: The findings suggest that SCL/tal-1 functions very early in hematopoietic development, either in specification of ventral mesoderm to a blood cell fate, or in formation or maintenance of immature progenitors.