Removal of the Bloom Syndrome DNA Helicase Extends the Utility of Imprecise Transposon Excision for Making Null Mutations in Drosophila

Transposable elements are frequently used in Drosophila melanogaster for imprecise excision screens to delete genes of interest. However, these screens are highly variable in the number and size of deletions that are recovered. Here, we show that conducting excision screens in mus309 mutant flies that lack DmBlm, the Drosophila ortholog of the Bloom syndrome protein, increases the percentage and overall size of flanking deletions recovered after excision of either P or Minos elements.

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Uncovering an allosteric mode of action for a selective inhibitor of human Bloom syndrome protein

10.1101/2020.11.30.403493 ◽

2020 ◽

Author(s):

X. Chen ◽

Y. Ali ◽

C.E.L. Fisher ◽

R. Arribas-Bosacoma ◽

M.B. Rajasekaran ◽

...

Keyword(s):

Synthetic Lethality ◽

Specific Inhibitor ◽

Bloom Syndrome ◽

Dna Helicase ◽

Holliday Junctions ◽

Dna Structures ◽

Recq Helicases ◽

Promising Target ◽

Opening And Closing ◽

Syndrome Protein

ABSTRACTBLM (Bloom syndrome protein) is a RECQ-family helicase involved in the dissolution of complex DNA structures and repair intermediates. Synthetic lethality analysis implicates BLM as a promising target in a range of cancers with defects in the DNA damage response, however selective small molecule inhibitors of defined mechanism are currently lacking. Here we identify and characterise a specific inhibitor of BLM’s ATPase-coupled DNA helicase activity, by allosteric trapping of a DNA-bound translocation intermediate. Crystallographic structures of BLM-DNA-ADP-inhibitor complexes identify a hitherto unknown interdomain interface, whose opening and closing are integral to translocation of ssDNA, and which provides a highly selective pocket for drug discovery. Comparison with structures of other RECQ helicases provides a model for branch migration of Holliday junctions by BLM.

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Evolution of the RECQ Family of Helicases: A Drosophila Homolog, Dmblm, Is Similar to the Human Bloom Syndrome Gene

Genetics ◽

10.1093/genetics/151.3.1027 ◽

1999 ◽

Vol 151 (3) ◽

pp. 1027-1039

Author(s):

Kohji Kusano ◽

Mark E Berres ◽

William R Engels

Keyword(s):

Drosophila Melanogaster ◽

Homo Sapiens ◽

Werner Syndrome ◽

Bloom Syndrome ◽

Dna Helicase ◽

Functional Similarity ◽

Premature Aging ◽

Model Systems ◽

C Elegans ◽

Blm Gene

Abstract Several eukaryotic homologs of the Escherichia coli RecQ DNA helicase have been found. These include the human BLM gene, whose mutation results in Bloom syndrome, and the human WRN gene, whose mutation leads to Werner syndrome resembling premature aging. We cloned a Drosophila melanogaster homolog of the RECQ helicase family, Dmblm (Drosophila melanogaster Bloom), which encodes a putative 1487-amino-acid protein. Phylogenetic and dot plot analyses for the RECQ family, including 10 eukaryotic and 3 prokaryotic genes, indicate Dmblm is most closely related to the Homo sapiens BLM gene, suggesting functional similarity. Also, we found that Dmblm cDNA partially rescued the sensitivity to methyl methanesulfonate of Saccharomyces cerevisiae sgs1 mutant, demonstrating the presence of a functional similarity between Dmblm and SGS1. Our analyses identify four possible subfamilies in the RECQ family: (1) the BLM subgroup (H. sapiens Bloom, D. melanogaster Dmblm, and Caenorhabditis elegans T04A11.6); (2) the yeast RECQ subgroup (S. cerevisiae SGS1 and Schizosaccharomyces pombe rqh1/rad12); (3) the RECQL/Q1 subgroup (H. sapiens RECQL/Q1 and C. elegans K02F3.1); and (4) the WRN subgroup (H. sapiens Werner and C. elegans F18C5.2). This result may indicate that metazoans hold at least three RECQ genes, each of which may have a different function, and that multiple RECQ genes diverged with the generation of multicellular organisms. We propose that invertebrates such as nematodes and insects are useful as model systems of human genetic diseases.

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Uncovering an allosteric mode of action for a selective inhibitor of human Bloom syndrome protein

eLife ◽

10.7554/elife.65339 ◽

2021 ◽

Vol 10 ◽

Author(s):

Xiangrong Chen ◽

Yusuf I Ali ◽

Charlotte EL Fisher ◽

Raquel Arribas-Bosacoma ◽

Mohan B Rajasekaran ◽

...

Keyword(s):

Synthetic Lethality ◽

Specific Inhibitor ◽

Bloom Syndrome ◽

Dna Helicase ◽

Holliday Junctions ◽

Dna Structures ◽

Recq Helicases ◽

Promising Target ◽

Opening And Closing ◽

Syndrome Protein

BLM (Bloom syndrome protein) is a RECQ-family helicase involved in the dissolution of complex DNA structures and repair intermediates. Synthetic lethality analysis implicates BLM as a promising target in a range of cancers with defects in the DNA damage response; however, selective small molecule inhibitors of defined mechanism are currently lacking. Here, we identify and characterise a specific inhibitor of BLM’s ATPase-coupled DNA helicase activity, by allosteric trapping of a DNA-bound translocation intermediate. Crystallographic structures of BLM-DNA-ADP-inhibitor complexes identify a hitherto unknown interdomain interface, whose opening and closing are integral to translocation of ssDNA, and which provides a highly selective pocket for drug discovery. Comparison with structures of other RECQ helicases provides a model for branch migration of Holliday junctions by BLM.

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Chromosomal Distribution of Transposable Elements in Drosophila melanogaster Test of the Ectopic Recombination Model for Maintenance of Insertion Site Number

Genetics ◽

10.1093/genetics/144.1.197 ◽

1996 ◽

Vol 144 (1) ◽

pp. 197-204

Author(s):

Christine Hoogland ◽

Christian Biémont

Keyword(s):

Drosophila Melanogaster ◽

Transposable Elements ◽

Dna Content ◽

Recombination Rate ◽

Alternative Hypothesis ◽

Insertion Site ◽

Polytene Chromosomes ◽

Negative Relationship ◽

Site Occupancy ◽

Site Number

Abstract Data of insertion site localization and site occupancy frequency of P, hobo, I, copia, mdg1, mdg3, 412, 297, and roo transposable elements (TEs) on the polytene chromosomes of Drosophila melanogaster were extracted from the literature. We show that TE insertion site number per chromosomal division was significantly correlated with the amount of DNA. The insertion site number weighted by DNA content was not correlated with recombination rate for all TEs except hobo, for which a positive correlation was detected. No global tendency emerged in the relationship between TE site occupancy frequency, weighted by DNA content, and recombination rate; a strong negative correlation was, however, found for the 3L arm. A possible dominant deleterious effect of chromosomal rearrangements due to recombination between TE insertions is thus not the main factor explaining the dynamics of TEs, since this hypothesis implies a negative relationship between recombination rate and both TE insertion site number and site occupancy frequency. The alternative hypothesis of selection against deleterious effects of insertional mutations is discussed.

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Solution structure of the RecQ C-terminal domain of human Bloom syndrome protein

Journal of Biomolecular NMR ◽

10.1007/s10858-014-9812-8 ◽

2014 ◽

Vol 58 (2) ◽

pp. 141-147 ◽

Cited By ~ 5

Author(s):

Chin-Ju Park ◽

Junsang Ko ◽

Kyoung-Seok Ryu ◽

Byong-Seok Choi

Keyword(s):

Solution Structure ◽

Bloom Syndrome ◽

Terminal Domain ◽

Syndrome Protein

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Interaction of replication protein A with two acidic peptides from human Bloom syndrome protein

FEBS Letters ◽

10.1002/1873-3468.12992 ◽

2018 ◽

Vol 592 (4) ◽

pp. 547-558 ◽

Cited By ~ 9

Author(s):

Donguk Kang ◽

Sungjin Lee ◽

Kyoung‐Seok Ryu ◽

Hae‐Kap Cheong ◽

Eun‐Hee Kim ◽

...

Keyword(s):

Protein A ◽

Replication Protein A ◽

Bloom Syndrome ◽

Replication Protein ◽

Syndrome Protein ◽

Acidic Peptides

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S elements: a family of Tc1-like transposons in the genome of Drosophila melanogaster.

Genetics ◽

10.1093/genetics/141.4.1425 ◽

1995 ◽

Vol 141 (4) ◽

pp. 1425-1438 ◽

Cited By ~ 1

Author(s):

P J Merriman ◽

C D Grimes ◽

J Ambroziak ◽

D A Hackett ◽

P Skinner ◽

...

Keyword(s):

Drosophila Melanogaster ◽

Amino Acid ◽

Transposable Elements ◽

Sibling Species ◽

Inverted Repeat ◽

Open Reading Frame ◽

Drosophila Species ◽

Insertion Mutation ◽

Reading Frame ◽

Diploid Genome

Abstract The S elements form a diverse family of long-inverted-repeat transposons within the genome of Drosophila melanogaster. These elements vary in size and sequence, the longest consisting of 1736 bp with 234-bp inverted terminal repeats. The longest open reading frame in an intact S element could encode a 345-amino acid polypeptide. This polypeptide is homologous to the transposases of the mariner-Tc1 superfamily of transposable elements. S elements are ubiquitous in D. melanogaster populations and also appear to be present in the genomes of two sibling species; however, they seem to be absent from 17 other Drosophila species that were examined. Within D. melanogaster strains, there are, on average, 37.4 cytologically detectable S elements per diploid genome. These elements are scattered throughout the chromosomes, but several sites in both the euchromatin and beta heterochromatin are consistently occupied. The discovery of an S-element-insertion mutation and a reversion of this mutation indicates that S elements are at least occasionally mobile in the D. melanogaster genome. These elements seem to insert at an AT dinucleotide within a short palindrome and apparently duplicate that dinucleotide upon insertion.

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Bloom syndrome protein restrains innate immune sensing of micronuclei by cGAS

Journal of Experimental Medicine ◽

10.1084/jem.20181329 ◽

2019 ◽

Vol 216 (5) ◽

pp. 1199-1213 ◽

Cited By ~ 19

Author(s):

Matthieu Gratia ◽

Mathieu P. Rodero ◽

Cécile Conrad ◽

Elias Bou Samra ◽

Mathieu Maurin ◽

...

Keyword(s):

Dna Damage ◽

Immune Responses ◽

Genome Instability ◽

Bloom Syndrome ◽

Innate Immune ◽

Genome Integrity ◽

Immune Sensing ◽

Syndrome Protein ◽

Innate Immune Sensing ◽

Exonuclease Trex1

Cellular innate immune sensors of DNA are essential for host defense against invading pathogens. However, the presence of self-DNA inside cells poses a risk of triggering unchecked immune responses. The mechanisms limiting induction of inflammation by self-DNA are poorly understood. BLM RecQ–like helicase is essential for genome integrity and is deficient in Bloom syndrome (BS), a rare genetic disease characterized by genome instability, accumulation of micronuclei, susceptibility to cancer, and immunodeficiency. Here, we show that BLM-deficient fibroblasts show constitutive up-regulation of inflammatory interferon-stimulated gene (ISG) expression, which is mediated by the cGAS–STING–IRF3 cytosolic DNA–sensing pathway. Increased DNA damage or down-regulation of the cytoplasmic exonuclease TREX1 enhances ISG expression in BLM-deficient fibroblasts. cGAS-containing cytoplasmic micronuclei are increased in BS cells. Finally, BS patients demonstrate elevated ISG expression in peripheral blood. These results reveal that BLM limits ISG induction, thus connecting DNA damage to cellular innate immune response, which may contribute to human pathogenesis.

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