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FLASH GENE
Symbol BLM contributors: mct/ - updated : 02-09-2018
HGNC name Bloom syndrome, RecQ helicase-like
HGNC id 1058
EXPRESSION
Type
   expressed in (based on citations)
organ(s)
SystemOrgan level 1Organ level 2Organ level 3Organ level 4LevelPubmedSpeciesStageRna symbol
blood / hematopoieticthymus    
Digestiveintestinelarge intestinecolon highly
Lymphoid/Immunelymph node   highly
 tonsils   highly
Reproductivemale systemtestis   
tissue
SystemTissueTissue level 1Tissue level 2LevelPubmedSpeciesStageRna symbol
Lymphoid    
cell lineage spermatocytes
cell lines
fluid/secretion
at STAGE
cell cycle     cell cycle, interphase, G1, S, G2, M
PROTEIN
PHYSICAL PROPERTIES
STRUCTURE
motifs/domains
  • seven RecQ helicase domains (BLM helicase)
  • an acidic motif and two putative nuclear localization signals (NLS), in the C terminus
  • C-terminal domain is essential for strand annealing and a 60 AA stretch is important for both ssDNA binding and strand annealing
  • helicase and RNaseD C-terminal (HRDC) domain, conserved among members of the RecQ helicase family, regulating helicase activity by virtue of variations in its surface AAs, and that may be adapted for a unique function among RecQ helicases--that of bridging protein and DNA interactions
  • HOMOLOGY
    interspecies homolog to murine Blm (77.6pc)
    intraspecies homolog to RECQL5
    Homologene
    FAMILY
  • helicase family
  • RecQ subfamily
  • CATEGORY enzyme , DNA associated
    SUBCELLULAR LOCALIZATION     intracellular
    intracellular,cytoplasm
    intracellular,nucleus,nucleoplasm,nuclear bodies,nuclear speckles
    intracellular,nucleus,chromatin/chromosome
    intracellular,nucleus,nucleolus
    text
  • colocalizing with RPA heterotrimeric ss DNA binding protein in meiotic prophase nuclei of spermatocytes division, cell cycle, M, prophase
  • colocalizing transitorily with RPA, PML in nuclear bodies
  • present in replication fork
  • in mitotic cells, BLM and RMI2 were mostly present in the nucleoplasm
  • BLM is expressed only in dividing cells; it is absent or greatly reduced in quiescent stem cells or in terminally differentiated non-dividing cell
  • basic FUNCTION
  • DNA helicase, ATP-dependent, atypical and highly DNA structure specific, unwinding single and double strand DNA in a 3'->5' direction, promoting an ATP-dependent branch migration of Holliday junctions
  • putatively suppressor of homologous recombination between closely opposed and replicating strands, and selected target during the execution of apoptosis
  • playing a role in recombination-mediated telomere lengthening
  • DNA damage sensor signaling the formation of DNA damage induced foci
  • playing a conserved role in recovery from perturbations in DNA replication and likely RecQ helicases act to restore productive DNA replication following S-phase arrest and hence prevent subsequent genomic instability
  • playing a role in chromosome segregation in addition to its function during DNA replication and repair
  • involved in the promotion of single-stranded DNA (ssDNA) annealing
  • functioning in dissociating alternative DNA structures during recombination and/or replication at telomeric ends
  • with TOP3A execute the dissolution of sister chromatids
  • might be involved in both early and late steps of homologous recombination
  • might regress replication forks as part of a genome maintenance pathway
  • having an anti-recombination role
  • involved in disruption of the Rad51-ssDNA (single-stranded DNA) filament, an active species that promotes homologous recombination, and stimulation of DNA repair synthesis
  • playing a a role with EXO1 in the initiation of recombinational DNA repair
  • stimulating DNA strand exchange activity of RAD51 without ATP hydrolysis
  • functions as a Holliday junction dissolvase
  • role in the maintenance of gene cluster genomic integrity
  • performs double-stranded DNA unwinding by fully active duplex destabilization
  • regulates several steps of homologous recombination (HR)-dependent repair of double-strand DNA breaks
  • appears to be a master regulator that is needed by INSL6 as well as by the TOP3/RMI complex to execute diverse functions in order to maintain normal replication and genome stability
  • BRIP1 catalytic activity and its effect on BLM protein stability contribute to preservation of genomic stability and a normal response to replication stress
  • WRN and BLM are critical for maintaining genomic stability and thought to function in accurate resolution of replication blockage
  • ERCC6L and BLM decorate ultrafine histone-negative DNA threads that link the segregating sister centromeres during anaphase
  • ERCC6L and BLM limit histone association with anaphase centromeric DNA threads and promote their resolution
  • BLM and RECQL4 have coordinated activities that promote genome stability
  • ERCC6L and BLM were required for the correct recruitment to the centromere of active TOP2A, an enzyme specialized in the catenation/decatenation process
  • BLM and ERCC6L cooperate in rendering centromeric catenates accessible to TOP2A, thereby facilitating correct centromere disjunction and preventing the formation of supernumerary centromeric ultrafine anaphase bridges
  • maintains genome integrity, at least in part, by suppressing illegitimate recombination events
  • mediates a checkpoint response to stabilize the replication machinery at stalled forks, thereby preventing replisome dissociation and an irreversible fork collapse
  • possible roles of BLM helicase in the recombination-mediated mechanism of telomere elongation
  • BLM promotes DNA end resection as part of the BLM-TOP3A-RMI1-RMI2 complex
  • BLM functions in 2 distinct pathways requiring different modifications: BLM functions to suppress SCE formation and in a second pathway, its phosphorylations are essential for suppression of chromosomal radial formation
  • BLM helicase has pivotal functions at the crossroads of DNA replication, recombination, and repair
  • FANCM and BLM complex work together at stalled forks to promote both Fanconi anemia repair and replication traverse pathways of interstrand crosslinks (ICLs)
  • CELLULAR PROCESS cell life, cell death/apoptosis
    nucleotide, replication
    nucleotide, recombination
    nucleotide, repair, recombination
    nucleotide, genomic integrity
    PHYSIOLOGICAL PROCESS
    PATHWAY
    metabolism
    signaling
    chromosome instability pathway
    a component
  • BLM-Top3A implicated in the regulation of recombination in somatic cells
  • component of the BRCA1-associated genome surveillance complex (BASC)
  • part of a multiprotein complex that protects genome stability
  • BLM-DNA2-RPA-NBN and EXO1-BLM-RPA-NBN constitute two DNA end resection machineries for human DNA break repair
  • BLM forms the BTRR complex with topoisomerase III alpha (TOP3A) and RecQ-mediated genome instability proteins 1 and 2 (RMI1 and RMI2)
  • INTERACTION
    DNA binding
    RNA
    small molecule metal binding, nucleotide,
  • Mg2+
  • ATP
  • protein
  • forms a complex with DNA topoisomerase IIIalpha (TOP3A)
  • MSH1
  • MLH1 (for some aspects of genetic recombination)
  • TRF1 and TRF2 (regulating BLM activity on telomeric structures)
  • WRN
  • DNA mismatch repair protein MSH6
  • interacts with proteins involved in DNA replication, recombination, and repair and is required for the repair of stalled-replication forks and in the DNA damage response
  • interaction with RPA or WRN helicases plays an important role in the mechanism for RPA stimulation of helicase-catalyzed DNA unwinding
  • interacting with ubiquitinated FANCD2
  • interacting with RMI1
  • interacting with POLD4
  • stimulates the nucleolytic activity of exonuclease 1 (EXO1), a 5prime/3primedouble-stranded DNA exonuclease
  • interacting with XRCC3 (disruption of XRCC3 suppresses methanesulfonate and UV sensitivity and the methyl methanesulfonate- and UV-induced chromosomal aberrations of BLM cells, indicating that BLM acts downstream of XRCC3)
  • TOP3A is a type IA DNA topoisomerase that functions with BLM and RMI1 to resolve DNA replication and recombination intermediates
  • BLM and and BRIP1 were found to interact physically and functionally in human cells
  • ERCC6L binds to BLM and enables BLM localization to anaphase centromeric threads
  • SUPV3L1 interact with BLM and WRN, members of the RecQ helicase family involved in multiple DNA metabolic processes, and in protection and stabilization of the genome
  • functional relationship between BLM, ERCC6L and TOP2A in the centromere decatenation process
  • physical and functional interaction between BLM and RECQL4
  • SPIDR is the link between BLM and the HR machinery
  • SPIDR independently interacts with BLM and RAD51 and promotes the formation of a BLM/RAD51-containing complex of biological importance
  • novel role for UIMC1 in preventing proteasomal degradation of BLM in unstressed cells
  • BRCA1 and BLM interact with RAD50 predominantly in S- and G2-phases, respectively
  • WRN and BLM act epistatically with DNA2 to promote the long-range resection of double strand break ends in human cells
  • TOP3A stimulates DNA unwinding by BLM in a manner that is potentiated by RMI1-RMI2, and the processivity of resection is reliant on the TOP3A-RMI1-RMI2 complex
  • DNA2 motor promotes the enzyme capacity to degrade dsDNA in conjunction with BLM or WRN and thus promote the repair of broken DNA
  • BLM activates AKT1 and AKT1S1 to promote Prostate cancer (PC) cell proliferation and survival
  • EXO5 is epistatic to BLM at stalled replication forks, and its nuclease activity is enhanced by BLM and RPA1
  • cell & other
    REGULATION
    activated by upregulated at the G1-S stage of the cell cycle
    RAD51L3-XRCC2 complex
    Other stimulated by single and DNA double strand breaks
    regulated by TERF1, TERF2
    negatively regulated by SUMO modification
    degraded by a proteasome-mediated pathway when BRIP1 is depleted
    ASSOCIATED DISORDERS
    corresponding disease(s) BLMS
    related resource Bloom Syndrome-BLMbase
    Other morbid association(s)
    TypeGene ModificationChromosome rearrangementProtein expressionProtein Function
    tumoral germinal mutation      
    in leukemia, lymphoma, skin tumor
    constitutional     --low  
    in G1 phase in order to promote NHEJ-mediated DNA repair, but it is stabilized by TOPBP1 in S phase cells in order to suppress sister chromatid exchange (SCE) and thereby prevent genomic instability
    Susceptibility to colorectal cancer
    Variant & Polymorphism
    Candidate gene
    Marker
    Therapy target
    ANIMAL & CELL MODELS