Molecular cloning of cDNA encoding human DNA helicase Q1 Which has homology to<i>Escherichia coli</i>Rec Q helicase and localization of the gene at chromosome 12p12

Seki, Masayuki; Miyazawa, Hiroshi; Tada, Shusuke; Yanagisawa, Junn; Yamaoka, T.; Hoshino, Shin‐ichi; Ozawa, Kazuo; Eki, Toshihiko; Nogami, Masahiro; Okumura, Katsuhiko; Taguchi, Hiroshi; Hanaoka, Fumio; Enomoto, Takemi

doi:10.1093/nar/22.22.4566

Cited by 150 publications

(108 citation statements)

References 50 publications

Supporting

Mentioning

107

Contrasting

Unclassified

Order By: Relevance

“…However, increased protease sensitivity in the presence of poly(U) is also seen with chymotrypsin, rendering these possibilities unlikely. Furthermore, an increase in protease sensitivity is observed with ssRNAs as small as U 20 (data not shown), which represents the approximate site size for RNA binding to eIF4A.…”

Section: Methodsmentioning

confidence: 89%

See 1 more Smart Citation

The DEAD Box Protein eIF4A. 2. A Cycle of Nucleotide and RNA-Dependent Conformational Changes

1998

View full text Add to dashboard Cite

Limited proteolysis experiments have been carried out with the DEAD box protein eIF4A. The results suggest that there is a substantial conformational change in eIF4A upon binding single-stranded RNA. Binding of ADP induces conformational changes in the free enzyme and the enzyme‚RNA complex, and binding of the ATP analogue AMP-PNP induces a conformational change in the enzyme‚RNA complex. The presence or absence of the γ-phosphate on the bound nucleotide acts as a switch, presumably via the Walker motifs, that mediates changes in protein conformation and, as described in the preceding paper in this issue, also mediates changes in RNA affinity. Thus, these results suggest that there is a series of changes in conformation and substrate affinity throughout the ATP hydrolysis reaction cycle. A model is proposed in which eIF4A and the eIF4A-like domains of the DEAD box proteins act as ATPdriven conformational switches or motors that produce movements or structural rearrangements of attached protein domains or associated proteins. These movements could then be used to rearrange RNA structures or RNA‚protein complexes.eIF4A is an RNA-activated ATPase (1, 2) that facilitates binding of the 40S ribosomal subunit to eukaryotic mRNAs (3,4). It is the archetypal member of the DEAD box family of proteins, as the other members of this family are made up of core eIF4A-like domains flanked by N-and C-terminal extensions (5). eIF4A can unwind small duplex RNAs in vitro in conjunction with another factor, eIF4B (2, 6-9). These and other observations have led to the proposal that the DEAD box proteins function as RNA helicases (2,6,8,(10)(11)(12)(13). Nevertheless, few details of the molecular functions or mechanisms of these enzymes are known.In the preceding paper in this issue, a minimal kinetic and thermodynamic framework for the eIF4A-catalyzed ATP hydrolysis reaction was established (14). It was demonstrated that the enzyme's affinity for RNA is modulated by the presence or absence of the γ-phosphate on the bound nucleotide. In addition, UV-induced RNA cross-linking experiments suggested that the presence or absence of the γ-phosphate also alters the conformation of the enzyme (9,14).To further explore ligand-induced conformational changes in eIF4A, limited proteolysis experiments were performed. These experiments provide evidence that distinct conformations of the enzyme are stabilized upon binding of the various combinations of substrates and products. The γ-phosphate of the bound nucleotide plays a key role in inducing both the conformational changes and changes in RNA affinity, suggesting that ATP binding and hydrolysis produce a cycle of conformational and RNA affinity changes in eIF4A. It is proposed that eIF4A and the eIF4A-like domains of the other DEAD box proteins act as ATP-dependent motors that produce motions in attached protein domains or associated proteins. Motions in these domains or associated proteins could then induce structural rearrangements in RNAs or RNA-protein complexes. EXPERIMENTAL PROCE...

show abstract

Section: Methodsmentioning

confidence: 89%

“…RNA concentrations and thermodynamic constants involving RNA are given in 20-mer units (nucleotide concentration divided by 20), unless otherwise noted. A 20-mer is approximately the minimal site size for RNA binding to eIF4A ((14-16); Unpublished Results).…”

Section: Methodsmentioning

confidence: 99%

The DEAD Box Protein eIF4A. 2. A Cycle of Nucleotide and RNA-Dependent Conformational Changes

1998

View full text Add to dashboard Cite

show abstract

“…YAC ICI36ECI was the smallest YAC found to be positive for KRAG by PCR, placing this gene between STS D12S1596 and D12S1316. The human DNA helicase Q1 (RECQL) (Seki et al, 1994;Puranam, 1995), the islet amyloid polypeptide (IAPP) (Hoovers et al, 1993) and lactate dehydrogenase isoenzyme B (LDHB) genes (Li et al, 1988) were previously mapped to band 12p12. We were able to localize these genes to the distal part of our YAC contig ( Figure 1a) and their order was determined by PCR on the di erent YACs.…”

Section: Candidate Genes and Semi-quantitative (Rt ± Pcr)mentioning

confidence: 99%

Identification of the critical region of 12p over-representation in testicular germ cell tumors of adolescents and adults

et al. 1998

View full text Add to dashboard Cite

Cytogenetically, testicular germ cell tumors of adolescents and adults (TGCTs) are characterized by gain of 12p-sequences, most often through isochromosome formation (i(12p)). Fluorescence in situ hybridization (FISH) has shown that i(12p))-negative TGCTs also cryptically contain extra 12p-sequences. The consistency of 12p-over-representation in all histological subtypes of TGCTs, including their preinvasive stage, suggests that gain of one or more genes on 12p is crucial in the development of this cancer. So far, studies aimed at the identi®cation of the relevant gene(s) were based on thè candidate-gene approach'. No convincing evidence in favor of or against a particular gene has been reported. We combined conventional karyotyping, comparative genomic hybridization, and FISH to identify TGCTs with ampli®cations of restricted regions of 12p. Out of 49 primary TGCTs (23 without i(12p), 13 with and 13 unknown), eight tumors (six without i(12p) and two unknown) showed ampli®cations corresponding to 12p11.1-p12.1. Using bicolour-FISH, physical mapping, and semi-quantitative polymerase chain reactions, the size of the shortest region of overlap of ampli®cation (SROA) was estimated to be between 1750 ± 3000 kb. In addition, we mapped a number of genes in and around this region. While fourteen known genes could be excluded as candidates based on their location outside this region, we demonstrate that KRAS2, JAW1 and SOX5 genes are localized within the SROA. While KRAS2 and JAW1 map to the proximal border of the SROA, SOX5 maps centrally in the SROA. KRAS2 and JAW1 are expressed in all TGCTs, whereas one 12p amplicon-positive TGCT lacks expression of SOX5. The critical region of 12p over-represented in TGCTs is less than 8% of the total length of the short arm of chromosome 12. It will be helpful in the identi®cation of the gene(s) involved in TGCT-development.

show abstract

“…The BLM protein has been identi®ed as a member in the DExH boxcontaining RecQ helicase subfamily (Ellis et al, 1995). Its primary sequence presents similarities with all known members in the RecQ subfamily, including Escherichia coli RecQ (Umezu et al, 1990), Saccharomyces cerevisiae Sgs1p (Ganglo et al, 1994;Watt et al, 1995), Schizosaccharomyces pombe Rqh1 (Stewart et al, 1997), Drosophila melanogaster DmBLM (Kusano et al, 1999), human RecQL (Puranam and Blackshear, 1994;Seki et al, 1994), human Wrn, the product of the Werner's syndrome gene (Yu et al, 1996) and the recently identi®ed human RecQ4 and RecQ5 proteins (Kitao et al, 1998). Chester et al (1998) developed a mouse model for the human Bloom's syndrome, and showed that mouse embryos homozygous for a targeted mutation in the murine Bloom's syndrome gene die by embryonic day 13.5, but little is known about function(s) of BLM.…”

Section: Introductionmentioning

confidence: 99%

Cell cycle regulation of the endogenous wild type Bloom's syndrome DNA helicase

et al. 2000

View full text Add to dashboard Cite

Bloom's syndrome (BS) is a rare human autosomal recessive disorder characterized by an increased risk to develop cancer of all types. BS cells are characterized by a generalized genetic instability including a high level of sister chromatid exchanges. BS arises through mutations in both alleles of the BLM gene which encodes a 3' ± 5' DNA helicase identi®ed as a member of the RecQ family. We developed polyclonal antibodies speci®c for the NH 2 -and COOH-terminal region of BLM. Using these antibodies, we analysed BLM expression during the cell cycle and showed that the BLM protein accumulates to high levels in S phase, persists in G2/ M and sharply declines in G1, strongly suggestive of degradation during mitosis. The BLM protein is subject to post-translational modi®cations in mitosis, as revealed by slow migrating forms of BLM found in both demecolcine-treated cells and in mitotic cells isolated from non-treated asynchronous populations. Phosphatase treatment indicated that phosphorylation events were solely responsible for the appearance of the retarded moieties, a possible signal for subsequent degradation. Together, these results are consistent with a role of BLM in a replicative (S phase) and/or post-replicative (G2 phase) process.

show abstract

Molecular cloning of cDNA encoding human DNA helicase Q1 Which has homology toEscherichia coliRec Q helicase and localization of the gene at chromosome 12p12

Cited by 150 publications

References 50 publications

The DEAD Box Protein eIF4A. 2. A Cycle of Nucleotide and RNA-Dependent Conformational Changes

The DEAD Box Protein eIF4A. 2. A Cycle of Nucleotide and RNA-Dependent Conformational Changes

Identification of the critical region of 12p over-representation in testicular germ cell tumors of adolescents and adults

Cell cycle regulation of the endogenous wild type Bloom's syndrome DNA helicase

Contact Info

Product

Resources

About