Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Bloom syndrome (BS) is a rare genetic disorder characterized by small body size, photosensitivity, immunodeficiency and a high predisposition to various types of cancer. BLM was identified as the causative gene for BS. The BLM protein is homologous to DNA helicase and has two basic amino acid clusters in its C-terminal region. Previously, we reported that the distal arm of these basic amino acids clusters in the BLM protein functioned as the nuclear localization signal (NLS) of the protein. In this study, we generated plasmid constructs for expression of enhanced green fluorescent protein (EGFP) fused with various BLM protein variants having a mutation with deletions or substitutions in the basic amino acid and analyzed the subcellular localization of the expressed proteins. The EGFP-fused protein containing the basic amino acid cluster region proximal to the C-terminus of BLM helicase was localized exclusively in the nucleus. However, the EGFP-BLM proteins that lacked either Arg1344 or Lys1346 distributed in both the cytoplasm and the nucleus equally. Deletion of Arg1347 also resulted in localization in both the nucleus and cytoplasm, and substitution of Arg1344, Lys1346, Arg1347 or Arg1348 with non-basic amino acids reduced the nuclear localization of BLM protein. Mouse BLM protein which also migrate to the nucleus has two basic amino acid clusters in the C-terminus and the basic amino acids (Lys1346-Pro1347-Lys1348-Arg1349-Arg1350) proximal to the C-terminus are conserved between mouse and human. These findings suggest that the Arg1344-Ser1345-Lys1346-Arg1347 sequence at the C-terminus of the human BLM protein is essential for nuclear localization of this protein.
Int J Mol Med 2000 May
PMID:Characterization of the nuclear localization signal in the DNA helicase responsible for Bloom syndrome. 1076 50

We describe the isolation of a new type of RecQ homologue in Drosophila melanogaster, RECQE. The Recqe gene consists of five exons and four introns, and encodes a protein of 1058 amino acids with a predicted molecular weight of 120,000 Da. The RECQE protein has seven helicase motifs. The helicase domain shows 42% identity overall to that of Escherichia coli RecQ DNA helicase, and is most closely related to Homo sapiens RecQL5 and Caenorhabditis elegans E03A3.2. The C-terminal region of RECQE protein is unique and the longest known among members of the RecQ superfamily. We demonstrate that the RECQE protein has DNA helicase activity and that the C-terminal region is dispensable for this activity. The RECQE mRNA accumulates in oocytes and is expressed at high levels in early embryos. We show for the first time that the expression of a RecQ homologue is developmentally regulated in embryos. These data suggest that the DNA helicase activity of RECQE might be involved in the DNA metabolism of early embryos.
Mol Gen Genet 2000 Mar
PMID:Identification of Drosophila melanogaster RECQE as a member of a new family of RecQ homologues that is preferentially expressed in early embryos. 1077 36

Escherichia coli RuvB protein, together with RuvA, promotes branch migration of Holliday junctions during homologous recombination and recombination repair. The RuvB molecular motor is an intrinsic ATP-dependent DNA helicase with a hexameric ring structure and its architecture has been suggested to be related to those of the members of the AAA+ protein class. In this study, we isolated a large number of plasmids carrying ruvB mutant genes and identified amino acid residues important for the RuvB functions by examining the in vivo DNA repair activities of the mutant proteins. Based on these mutational studies and amino acid conservation among various RuvBs, we identified 10 RuvB motifs that agreed well with the features of the AAA+ protein class and that distinguished the primary structure of RuvB from that of typical DNA/RNA helicases with seven conserved helicase motifs.
Mol Microbiol 2000 May
PMID:Mutational analysis of the functional motifs of RuvB, an AAA+ class helicase and motor protein for holliday junction branch migration. 1084 44

Bacteriophage T4 gene 59 helicase loading protein accelerates the loading of T4 gene 41 DNA helicase and is required for recombination-dependent DNA replication late in T4 phage infection. The crystal structure of 59 protein revealed a two-domain alpha-helical protein, whose N-terminal domain has strong structural similarity to the DNA binding domain of high mobility group family proteins (Mueser, T. C., Jones, C. E., Nossal, N. G., and Hyde, C. C. (2000) J. Mol. Biol. 296, 597-612). We have previously shown that 59 protein binds preferentially to fork DNA. Here we show that 59 protein binds to completely duplex forks but cannot load the helicase unless there is a single-stranded gap of more than 5 nucleotides on the fork arm corresponding to the lagging strand template. Consistent with the roles of these proteins in recombination, we find that 59 protein binds to and stimulates 41 helicase activity on Holliday junction DNA, and on a substrate that resembles a strand invasion structure. 59 protein forms a stable complex with wild type 41 helicase and fork DNA in the presence of adenosine 5'-O-(thiotriphosphate). The unwinding activity of 41 helicase missing 20 C-terminal amino acids is not stimulated by 59 protein, and it does not form a complex with 59 protein on fork DNA.
 ...
PMID:Interaction of the bacteriophage T4 gene 59 helicase loading protein and gene 41 helicase with each other and with fork, flap, and cruciform DNA. 1087 15

Mcm2-7 proteins that play an essential role in eukaryotic DNA replication contain DNA-dependent ATPase motifs in a central domain that, from yeast to mammals, is highly conserved. Our group has reported that a DNA helicase activity is associated with a 600 kDa human Mcm4, 6 and 7 complex. The structure of the Mcm4,6,7 complex was visualized by electron microscopy after negative staining with uranyl acetate. The complex contained toroidal forms with a central channel and also contained structures with a slit. Gel-shift analysis indicated that the level of affinity of the Mcm4,6,7 complex for single-stranded DNA was comparable to that of SV40 T antigen, although the Mcm4,6,7 complex required longer single-stranded DNA for the binding than did SV40 T antigen. The nucleoprotein complexes of Mcm4,6,7 and single-stranded DNA were visualized as beads in a queue or beads on string-like structures. The formation of these nucleoprotein complexes was erased by Mcm2 that is a potential inhibitor of the Mcm4,6,7 helicase. We also found that the DNA helicase activity of Mcm4,6,7 complex was inhibited by the binding of Mcm3,5 complex. These results support the notion that the Mcm4,6,7 complex functions as a DNA helicase and the formation of 600 kDa complex is essential for the activity.
J Mol Biol 2000 Jul 14
PMID:Electron microscopic observation and single-stranded DNA binding activity of the Mcm4,6,7 complex. 1088 41

The SGS1 gene of Saccharomyces cerevisiae is a homologue for the Bloom's syndrome and Werner's syndrome genes. The disruption of the SGS1 gene resulted in very poor sporulation, and the majority of the cells were arrested at the mononucleated stage. The recombination frequency measured by a return-to-growth assay was reduced considerably in sgs1 disruptants. However, double-strand break formation, which is a key event in the initiation of meiotic DNA recombination, occurred; crossover and noncrossover products were observed in the disruptants, although the amounts of these products were slightly decreased compared with those in wild-type cells. The spores produced by sgs1 disruptants showed relatively high viability. The sgs1 spo13 double disruptants sporulated poorly, like the sgs1 disruptants, but spore viability was reduced much more than with either sgs1 or spo13 single disruptants. Disruption of the RED1 or RAD17 gene partially alleviated the poor-sporulation phenotype of sgs1 disruptants, indicating that portions of the population of sgs1 disruptants are blocked by the meiotic checkpoint. The poor sporulation of sgs1 disruptants was complemented with a mutated SGS1 gene encoding a protein lacking DNA helicase activity; however, the mutated gene could suppress neither the sensitivity of sgs1 disruptants to methyl methanesulfonate and hydroxyurea nor the mitotic hyperrecombination phenotype of sgs1 disruptants.
Mol Cell Biol 2000 Sep
PMID:Sgs1 helicase activity is required for mitotic but apparently not for meiotic functions. 1093 17

The Mycobacterium leprae RuvA homologue (MlRuvA) was over-expressed in Escherichia coli and purified to homogeneity. The DNA-binding specificity and the functional interactions of MlRuvA with E. coli RuvB and RuvC (EcRuvB and EcRuvC) were examined using synthetic Holliday junctions. MlRuvA bound specifically to Holliday junctions and produced similar band-shift patterns as EcRuvA. Moreover, MlRuvA formed functional DNA helicase and branch-migration enzymes with EcRuvB, although the heterologous enzyme had a lower efficiency. These results demonstrate that the RuvA homologue of M. leprae is a functional branch-migration subunit. Whereas MlRuvA promoted branch-migration in combination with EcRuvB, it was unable to stimulate branch-migration-dependent resolution in a RuvABC complex. The inability to stimulate RuvC was not due to its failure to form heterologous RuvABC complexes on junctions, since such complexes were detected by co-immunoprecipitation. Most likely, the stability of the heterologous RuvABC complex and, possibly, the interactions between RuvA and RuvC were impaired, as gel-shift experiments failed to show mixed MlRuvA-EcRuvC-junction complexes. These results demonstrate that branch-migration per se and the assembly of a RuvABC complex on the Holliday junction are insufficient for RuvAB-dependent resolution of the junction by RuvC, suggesting that specific and intimate interactions between all three proteins are required for the function of a RuvABC "resolvasome".
J Mol Biol 2000 Aug 25
PMID:Functional interactions of Mycobacterium leprae RuvA with Escherichia coli RuvB and RuvC on holliday junctions. 1096 90

The Saccharomyces cerevisiae gene SGS1 encodes a DNA helicase that shows homology to the Escherichia coli protein RecQ and the products of the BLM and WRN genes in humans, which are defective in Bloom's and Werner's syndrome, respectively. Recently, it has been proposed that this helicase is involved in maintaining the integrity of the rDNA and that loss of Sgs1 function leads to accelerated aging. Sgs1 has been isolated on the basis of its genetic interaction with both topoisomerase I and topoisomerase III, as well as in a two-hybrid screen for proteins that interact with the C-terminal portion of topoisomerase II. We have defined the minimal structural elements of Sgs1 required for its interactions with the three topoisomerases, and demonstrate that the complex phenotypes associated with sgs1 mutants are a consequence of a dysfunctional Sgs1-Top3 complex. We also report that the synthetic relationship between mutations in SGS1 and SRS2, which encodes another helicase implicated in recombinational repair, likewise result from a dysfunctional Sgs1-Top3 interaction. Our findings indicate that Sgs1 may act on different DNA structures depending on the activity of topoisomerase I, Srs2 and topoisomerase III.
Mol Gen Genet 2000 Sep
PMID:Genetic analysis of the Saccharomyces cerevisiae Sgs1 helicase defines an essential function for the Sgs1-Top3 complex in the absence of SRS2 or TOP1. 1101 37

The UvsW protein of bacteriophage T4 is involved in many aspects of phage DNA metabolism, including repair, recombination, and recombination-dependent replication. UvsW has also been implicated in the repression of origin-dependent replication at late times of infection, when UvsW is normally synthesized. Two well-characterized T4 origins, ori(uvsY) and ori(34), are believed to initiate replication through an R-loop mechanism. Here we provide both in vivo and in vitro evidence that UvsW is an RNA-DNA helicase that catalyzes the dissociation of RNA from origin R-loops. Two-dimensional gel analyses show that the replicative intermediates formed at ori(uvsY) persist longer in a uvsW mutant infection than in a wild-type infection. In addition, the inappropriate early expression of UvsW protein results in the loss of these replicative intermediates. Using a synthetic origin R-loop, we also demonstrate that purified UvsW functions as a helicase that efficiently dissociates RNA from R-loops. These and previous results from a number of studies provide strong evidence that UvsW is a molecular switch that allows T4 replication to progress from a mode that initiates from R-loops at origins to a mode that initiates from D-loops formed by recombination proteins.
Mol Cell Biol 2001 Apr
PMID:UvsW protein regulates bacteriophage T4 origin-dependent replication by unwinding R-loops. 1128 50

The genomic instability of persons with Bloom's syndrome (BS) features particularly an increased number of sister-chromatid exchanges (SCEs). The primary cause of the genomic instability is mutation at BLM, which encodes a DNA helicase of the RecQ family. BLM interacts with Topoisomerase IIIalpha (Topo IIIalpha), and both BLM and Topo IIIalpha localize to the nuclear organelles referred to as the promyelocytic leukemia protein (PML) nuclear bodies. In this study we show, by analysis of cells that express various deletion constructs of green fluorescent protein (GFP)-tagged BLM, that the first 133 amino acids of BLM are necessary and sufficient for interaction between Topo IIIalpha and BLM. The Topo IIIalpha-interaction domain of BLM is not required for BLM's localization to the PML nuclear bodies; in contrast, Topo IIIalpha is recruited to the PML nuclear bodies via its interaction with BLM. Expression of a full-length BLM (amino acids 1-1417) in BS cells can correct their high SCEs to normal levels, whereas expression of a BLM fragment that lacks the Topo IIIalpha interaction domain (amino acids 133-1417) results in intermediate SCE levels. The deficiency of amino acids 133-1417 in the reduction of SCEs was not explained by a defect in DNA helicase activity, because immunoprecipitated 133-1417 protein had 4-fold higher activity than GFP-BLM. The data implicate the BLM-Topo IIIalpha complex in the regulation of recombination in somatic cells.
Hum Mol Genet 2001 Jun 01
PMID:Evidence for BLM and Topoisomerase IIIalpha interaction in genomic stability. 1140 10


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>