共查询到20条相似文献，搜索用时 62 毫秒
1.
Recognition of thymine adenine.base pairs by guanine in a pyrimidine triple helix motif 总被引：25，自引：0，他引：25
Oligonucleotide recognition offers a powerful chemical approach for the sequence-specific binding of double-helical DNA. In the pyrimidine-Hoogsteen model, a binding size of greater than 15 homopurine base pairs affords greater than 30 discrete sequence-specific hydrogen bonds to duplex DNA. Because pyrimidine oligonucleotides limit triple helix formation to homopurine tracts, it is desirable to determine whether oligonucleotides can be used to bind all four base pairs of DNA. A general solution would allow targeting of oligonucleotides (or their analogs) to any given sequence in the human genome. A study of 20 base triplets reveals that the triple helix can be extended from homopurine to mixed sequences. Guanine contained within a pyrimidine oligonucleotide specifically recognizes thymine.adenine base pairs in duplex DNA. Such specificity allows binding at mixed sites in DNA from simian virus 40 and human immunodeficiency virus. 相似文献
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[目的]研究靶向PRRSV核衣壳蛋白N基因的siRNA表达载体的构建及鉴定：[方法]设计并人工合成靶向PRRSV核蛋白N基因的3个siRNA靶序列,将其插入CMV启动子下游,克隆到真核表达载体pSilencer4．1-CMV中,对该重组表达载体进行酶切鉴定及DNA测序。[结果]成功构建了靶向核蛋白基因表达的siRNA干扰重组质粒载体pSilencer—N。[结论]该研究为进一步运用RNA干扰技术进行PRRSV防治研究奠定了基础。 相似文献
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Demers LM Ginger DS Park SJ Li Z Chung SW Mirkin CA 《Science (New York, N.Y.)》2002,296(5574):1836-1838
The use of direct-write dip-pen nanolithography (DPN) to generate covalently anchored, nanoscale patterns of oligonucleotides on both metallic and insulating substrates is described. Modification of DNA with hexanethiol groups allowed patterning on gold, and oligonucleotides bearing 5'-terminal acrylamide groups could be patterned on derivatized silica. Feature sizes ranging from many micrometers to less than 100 nanometers were achieved, and the resulting patterns exhibited the sequence-specific binding properties of the DNA from which they were composed. The patterns can be used to direct the assembly of individual oligonucleotide-modified particles on a surface, and the deposition of multiple DNA sequences in a single array is demonstrated. 相似文献
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Assembly of functional U1 and U2 human-amphibian hybrid snRNPs in Xenopus laevis oocytes 总被引：18，自引：0，他引：18
Oligonucleotides complementary to regions of U1 and U2 small nuclear RNAs (snRNAs), when injected into Xenopus laevis oocytes, rapidly induced the specific degradation of U1 and U2 snRNAs, respectively, and then themselves were degraded. After such treatment, splicing of simian virus 40 (SV40) late pre-mRNA transcribed from microinjected viral DNA was blocked in oocytes. If before introduction of SV40 DNA into oocytes HeLa cell U1 or U2 snRNAs were injected and allowed to assemble into small nuclear ribonucleoprotein particle (snRNP)-like complexes, SV40 late RNA was as efficiently spliced as in oocytes that did not receive U1 or U2 oligonucleotides. This demonstrates that oocytes can form fully functional hybrid U1 and U2 snRNPs consisting of human snRNA and amphibian proteins. 相似文献
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Binding of the Wilms' tumor locus zinc finger protein to the EGR-1 consensus sequence 总被引：55，自引：0，他引：55
F J Rauscher J F Morris O E Tournay D M Cook T Curran 《Science (New York, N.Y.)》1990,250(4985):1259-1262
The Wilms' tumor locus (WTL) at 11p13 contains a gene that encodes a zinc finger-containing protein that has characteristics of a DNA-binding protein. However, binding of this protein to DNA in a sequence-specific manner has not been demonstrated. A synthetic gene was constructed that contained the zinc finger region, and the protein was expressed in Escherichia coli. The recombinant protein was used to identify a specific DNA binding site from a pool of degenerate oligonucleotides. The binding sites obtained were similar to the sequence recognized by the early growth response-1 (EGR-1) gene product, a zinc finger-containing protein that is induced by mitogenic stimuli. A mutation in the zinc finger region of the protein originally identified in a Wilms' tumor patient abolished its DNA-binding activity. These results suggest that the WTL protein may act at the DNA binding site of a growth factor-inducible gene and that loss of DNA-binding activity contributes to the tumorigenic process. 相似文献
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Selective cleavage of human DNA: RecA-assisted restriction endonuclease (RARE) cleavage 总被引：35，自引：0，他引：35
Current methods for sequence-specific cleavage of large segments of DNA are severely limited because of the paucity of possible cleavage sites. A method is described whereby any Eco RI site can be targeted for specific cleavage. The technique is based on the ability of RecA protein from Escherichia coli to pair an oligonucleotide to its homologous sequence in duplex DNA and to form a three-stranded complex. This complex is protected from Eco RI methylase; after methylation and RecA protein removal, Eco RI restriction enzyme cleavage was limited to the site previously protected from methylation. When pairs of oligonucleotides are used, a specific fragment can be cleaved out of genomes. The method was tested on lambda phage, Escherichia coli, and human DNA. Fragments exceeding 500 kilobases in length and yields exceeding 80 percent could be obtained. 相似文献
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Unwinding of duplex DNA from the SV40 origin of replication by T antigen 总被引：49，自引：0，他引：49
The T antigen specified by SV40 virus is the only viral-encoded protein required for replication of SV40 DNA. T antigen has two activities that appear to be essential for viral DNA replication: specific binding to duplex DNA at the origin of replication and helicase activity that unwinds the two DNA strands. As judged by electron microscopy, DNA unwinding is initiated at the origin of replication and proceeds bidirectionally. Either linear or circular DNA molecules containing the origin of replication are effective substrates; with closed circular DNA, a topoisomerase capable of removing positive superhelical turns is required for an efficient reaction. Presence of an origin sequence on duplex DNA and a single-strand DNA-binding protein appear to be the only requirements for T antigen to catalyze unwinding. This reaction mediated by T antigen defines a likely pathway to precise initiation of DNA replication: (i) the sequence-specific binding activity locates the origin sequence, (ii) the duplex DNA is unwound at this site, and (iii) the DNA polymerase and primase begin DNA replication. A similar pathway has been inferred for the localized initiation of DNA replication by bacteriophage lambda and by Escherichia coli in which a sequence-specific binding protein locates the origin and directs the DnaB helicase to this site. Observations with the SV40 system indicate that localized initiation of duplex DNA replication may be similar for prokaryotes and eukaryotes. 相似文献
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A DNA nanostructure consisting of four four-arm junctions oriented with a square aspect ratio was designed and constructed. Programmable self-assembly of 4 x 4 tiles resulted in two distinct lattice morphologies: uniform-width nanoribbons and two-dimensional nanogrids, which both display periodic square cavities. Periodic protein arrays were achieved by templated self-assembly of streptavidin onto the DNA nanogrids containing biotinylated oligonucleotides. On the basis of a two-step metallization procedure, the 4 x 4 nanoribbons acted as an excellent scaffold for the production of highly conductive, uniform-width, silver nanowires. 相似文献
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Keren K Krueger M Gilad R Ben-Yoseph G Sivan U Braun E 《Science (New York, N.Y.)》2002,297(5578):72-75
Recent advances in the realization of individual molecular-scale electronic devices emphasize the need for novel tools and concepts capable of assembling such devices into large-scale functional circuits. We demonstrated sequence-specific molecular lithography on substrate DNA molecules by harnessing homologous recombination by RecA protein. In a sequence-specific manner, we patterned the coating of DNA with metal, localized labeled molecular objects and grew metal islands on specific sites along the DNA substrate, and generated molecularly accurate stable DNA junctions for patterning the DNA substrate connectivity. In our molecular lithography, the information encoded in the DNA molecules replaces the masks used in conventional microelectronics, and the RecA protein serves as the resist. The molecular lithography works with high resolution over a broad range of length scales from nanometers to many micrometers. 相似文献
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Sequence-specific DNA binding by a short peptide dimer 总被引：33，自引：0，他引：33
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Schöning K Scholz P Guntha S Wu X Krishnamurthy R Eschenmoser A 《Science (New York, N.Y.)》2000,290(5495):1347-1351
TNAs [(L)-alpha-threofuranosyl oligonucleotides] containing vicinally connected (3'-->2') phosphodiester bridges undergo informational base pairing in antiparallel strand orientation and are capable of cross-pairing with RNA and DNA. Being derived from a sugar containing only four carbons, TNA is structurally the simplest of all potentially natural oligonucleotide-type nucleic acid alternatives studied thus far. This, along with the base-pairing properties of TNA, warrants close scrutiny of the system in the context of the problem of RNA's origin. 相似文献
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A ligase-mediated gene detection technique 总被引：71，自引：0，他引：71
An assay for the presence of given DNA sequences has been developed, based on the ability of two oligonucleotides to anneal immediately adjacent to each other on a complementary target DNA molecule. The two oligonucleotides are then joined covalently by the action of a DNA ligase, provided that the nucleotides at the junction are correctly base-paired. Thus single nucleotide substitutions can be distinguished. This strategy permits the rapid and standardized identification of single-copy gene sequences in genomic DNA. 相似文献
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Identification of a zinc finger protein that binds to the sterol regulatory element 总被引：36，自引：0，他引：36
T B Rajavashisth A K Taylor A Andalibi K L Svenson A J Lusis 《Science (New York, N.Y.)》1989,245(4918):640-643
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The 35-nucleotide spliced leader sequence is common to all trypanosome messenger RNA's 总被引：38，自引：0，他引：38
J A Walder P S Eder D M Engman S T Brentano R Y Walder D S Knutzon D M Dorfman J E Donelson 《Science (New York, N.Y.)》1986,233(4763):569-571
In Trypanosomatidae the messenger RNA's (mRNA's) that code for the variant surface glycoproteins (VSG's), tubulins, calmodulin, and at least a subset of other proteins contain a common 35-nucleotide leader sequence at their 5' ends. Hybrid-arrested in vitro translation has been used to show that all mRNA's in both African and South American trypanosomes contain this 35-nucleotide sequence. Oligonucleotides complementary to this sequence blocked translation of all trypanosome mRNA's in a rabbit reticulocyte lysate system, but did not inhibit translation of mRNA's from other organisms lacking this sequence. An oligonucleotide complementary to the VSG mRNA downstream from the spliced leader sequence arrested only VSG synthesis. Thus, the 35-nucleotide leader sequence is a general feature of all trypanosome mRNA's. The high specificity of oligonucleotides complementary to the spliced leader for their target sequence suggests that analogues permeable to the cell membrane may be useful in the treatment of trypanosomal infections. 相似文献
17.
Sequence-specific packaging of DNA in human sperm chromatin 总被引：20，自引：0，他引：20
J M Gatewood G R Cook R Balhorn E M Bradbury C W Schmid 《Science (New York, N.Y.)》1987,236(4804):962-964
The DNA in human sperm chromatin is packaged into nucleoprotamine (approximately 85%) and nucleohistone (approximately 15%). Whether these two chromatin fractions are sequence-specific subsets of the spermatozoon genome is the question addressed in this report. Sequence-specific packaging would suggest distinct structural and functional roles for the nucleohistone and nucleoprotamine in late spermatogenesis or early development or both. After removal of histones with 0.65M NaCl, exposed DNA was cleaved with Bam HI restriction endonuclease and separated by centrifugation from insoluble nucleoprotamine. The DNA sequence distribution of nucleohistone DNA in the supernatant and nucleoprotamine DNA in the pellet was compared by cloning size-selected single-copy sequences and by using the derived clones as probes of nucleohistone DNA and nucleoprotamine DNA. Two clones derived from nucleohistone DNA preferentially hybridized to nucleohistone DNA, and two clones derived from nucleoprotamine DNA preferentially hybridized to nucleoprotamine DNA, which demonstrated the existence of sequence-specific nucleohistone and nucleoprotamine components within the human spermatozoon. 相似文献
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Site-specific cleavage of a yeast chromosome by oligonucleotide-directed triple-helix formation 总被引：18，自引：0，他引：18
Oligonucleotides equipped with EDTA-Fe can bind specifically to duplex DNA by triple-helix formation and produce double-strand cleavage at binding sites greater than 12 base pairs in size. To demonstrate that oligonucleotide-directed triple-helix formation is a viable chemical approach for the site-specific cleavage of large genomic DNA, an oligonucleotide with EDTA-Fe at the 5' and 3' ends was targeted to a 20-base pair sequence in the 340-kilobase pair chromosome III of Saccharomyces cerevisiae. Double-strand cleavage products of the correct size and location were observed, indicating that the oligonucleotide bound and cleaved the target site among almost 14 megabase pairs of DNA. Because oligonucleotide-directed triple-helix formation has the potential to be a general solution for DNA recognition, this result has implications for physical mapping of chromosomes. 相似文献
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