Sterility of
            <i>Drosophila</i>
            with Mutations in the Bloom Syndrome Gene--Complementation by
            <i>Ku70</i>

Kusano, Kohji; Johnson-Schlitz, Dena M.; Engels, William R.

doi:10.1126/science.291.5513.2600

Cited by 101 publications

(97 citation statements)

References 24 publications

(9 reference statements)

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“…The organizational overlap between IRBP DNA binding and transposase cleavage sites makes the IRBP complex a prime cellular candidate to influence some aspect of the P-element transposition cycle. Several putative IRBP proteins copurified with observed IRBP DNA-binding activity or unambiguously promoted DNA repair posttransposase P-element cleavage (Ku 70 and mus309/DmBLM) (31,34). None, however, could reconstitute site-specific DNA binding to the P-element 31-bp TIRs.…”

Section: Discussionmentioning

confidence: 99%

Drosophila IRBP bZIP heterodimer binds P-element DNA and affects hybrid dysgenesis

Francis

Roche

Cho

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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In Drosophila, P-element transposition causes mutagenesis and genome instability during hybrid dysgenesis. The P-element 31-bp terminal inverted repeats (TIRs) contain sequences essential for transposase cleavage and have been implicated in DNA repair via protein-DNA interactions with cellular proteins. The identity and function of these cellular proteins were unknown. Biochemical characterization of proteins that bind the TIRs identified a heterodimeric basic leucine zipper (bZIP) complex between an uncharacterized protein that we termed "Inverted Repeat Binding Protein (IRBP) 18" and its partner Xrp1. The reconstituted IRBP18/Xrp1 heterodimer binds sequence-specifically to its dsDNA-binding site within the P-element TIRs. Genetic analyses implicate both proteins as critical for repair of DNA breaks following transposase cleavage in vivo. These results identify a cellular protein complex that binds an active mobile element and plays a more general role in maintaining genome stability.T ransposable elements contribute significantly to the organization and evolution of all eukaryotic genomes. Recent estimates of transposon content within the Drosophila melanogaster genome are between 5% and 10%, and in humans over half the genome is composed of mobile elements (1, 2). Although many of these elements, including the Drosophila P-element transposon, are still active (3), the cellular mechanisms used to combat the genotoxic effects of DNA double-strand breaks (DSBs) generated by transpositional recombination are not fully understood. The Drosophila P-transposable element provides an excellent model for understanding the ancient mechanisms used by the cell to counteract newly invading parasitic mobile DNA elements (4).The P-element transposon is a mobile DNA element that spread through wild populations of D. melangaster ∼100 y ago after most common laboratory strains were isolated (5, 6). P elements were identified by studying a genetic syndrome called "P-M hybrid dysgenesis." It was observed that males from wild populations (P strains) crossed to females from isolated laboratory stocks (M strains) yielded progeny that had germline mutations, temperature-sensitive sterility, and atypical male recombination (6). Reciprocal crosses yielded phenotypically normal progeny. The P element was shown to be the causative agent of these so-called P-M hybrid dysgenesis phenotypes by molecular analyses showing that P elements were present in variable locations in P strains yet totally absent from most M strains (7,8).The Drosophila P-element transposon encodes a GTP-dependent site-specific DNA transposase/integrase family enzyme (9, 10). At each end of the P-element transposon are perfect 31-bp terminal inverted repeats (TIRs), 11-bp internal inverted repeats that serve as enhancers of transposition, and internal 10-bp transposase binding sites (11-13) (Fig. 1A). The P-element transposase catalyzes DNA cleavage within the 31-bp TIRs to create 17-nt 3′ single-strand extensions at both the donor site and the transposon ends (14, 15)...

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Section: Discussionmentioning

confidence: 99%

Drosophila IRBP bZIP heterodimer binds P-element DNA and affects hybrid dysgenesis

Francis

Roche

Cho

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…This analysis placed the map location of ninaG within region 86E3-87A9 on the right arm of the third chromosome. To further refine this map position, P-element-induced deletions within the 86E region (27) were tested for complementation with ninaG mutants. Df(3R)thoR1, Df(3R)pros235, and Df(3R)pros640, but not Df(3R)T7, failed to complement the low rhodopsin phenotype of ninaG (Fig.…”

Section: Resultsmentioning

confidence: 99%

The Drosophila ninaG Oxidoreductase Acts in Visual Pigment Chromophore Production

Sarfare

Ahmad

Joyce

et al. 2005

Journal of Biological Chemistry

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“…It is also possible that Ku and BLM bind to each other and coordinately affect WRN. A genetic interaction between Drosophila BLM and Ku70 was recently reported (34), but this interaction has not been noted in human cells. Our finding that Ku stimulates the WRN exonuclease activity in the presence of BLM indicates that the inhibition of WRN exonuclease by BLM is specific and not due to the presence of a potential contaminant in the BLM preparation.…”

Section: Lack Of Synergism Between Wrn and Blm In The Helicase Reactimentioning

confidence: 99%

Colocalization, Physical, and Functional Interaction between Werner and Bloom Syndrome Proteins

Kobbe¹,

Karmakar²,

Dawut³

et al. 2002

Journal of Biological Chemistry

124

104

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The RecQ helicase family comprises a conserved group of proteins implicated in several aspects of DNA metabolism. Three of the family members are defective in heritable diseases characterized by abnormal growth, premature aging, and predisposition to malignancies. These include the WRN and BLM gene products that are defective in Werner and Bloom syndromes, disorders which share many phenotypic and cellular characteristics including spontaneous genomic instability. Here, we report a physical and functional interaction between BLM and WRN. These proteins were coimmunoprecipitated from a nuclear matrix-solubilized fraction, and the purified recombinant proteins were shown to interact directly. Moreover, BLM and WRN colocalized to nuclear foci in three human cell lines. Two regions of WRN that mediate interaction with BLM were identified, and one of these was localized to the exonuclease domain of WRN. Functionally, BLM inhibited the exonuclease activity of WRN. This is the first demonstration of a physical and functional interaction between RecQ helicases. Our observation that RecQ family members interact provides new insights into the complex phenotypic manifestations resulting from the loss of these proteins. Werner syndrome (WS)1 is a hallmark premature aging syndrome associated with increased malignancies and genomic instability (1). The protein defective in WS, Werner syndrome protein (WRN), is an ATP-dependent 3Ј-5Ј-helicase and also has a 3Ј-5Ј-exonuclease activity (2). Recently, a number of protein partners for WRN have been identified. These include proliferating cell nuclear antigen (3), replication protein A (RPA) (4), DNA topoisomerase I (3), the Ku heterodimer (5, 6), DNA polymerase ␦ (7), and p53 (8). Some of these interactions are not only physical but are also functional. Each of these binding proteins is involved in some form of DNA metabolism, such as DNA recombination, replication, and repair, and in the resolution of alternative DNA structures (1, 2). This suggests that WRN plays a role in a number of key DNA metabolic pathways. Bloom syndrome (BS) is a highly cancer-prone disease associated with increased genomic instability and elevated sister chromatid exchanges. The protein defective in this disorder, Bloom syndrome protein (BLM), is a 3Ј-5Ј-helicase (9). BLM binds to RPA, p53, topoisomerase III␣, and RAD51 and is a component of the BRCA1-associated genome surveillance complex (10). This links BLM with proteins implicated in several aspects of DNA metabolism (DNA recombination, replication, and repair).BLM and WRN both belong to the RecQ family of helicases, which are conserved from Escherichia coli to human (11). WRN is unique among the human RecQ helicases in having an exonuclease domain in the N-terminal region of the protein. A number of the RecQ helicases have been purified, and their biochemical properties have been characterized (11). There is considerable interest in the substrate specificities of each of these enzymes and in possible differences between them. However, so far there h...

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Sterility of Drosophila with Mutations in the Bloom Syndrome Gene--Complementation by Ku70

Cited by 101 publications

References 24 publications

Drosophila IRBP bZIP heterodimer binds P-element DNA and affects hybrid dysgenesis

Drosophila IRBP bZIP heterodimer binds P-element DNA and affects hybrid dysgenesis

The Drosophila ninaG Oxidoreductase Acts in Visual Pigment Chromophore Production

Colocalization, Physical, and Functional Interaction between Werner and Bloom Syndrome Proteins

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