168 results about "Circular DNA" patented technology

The present invention provides a method for the rapid simultaneous production of a plurality of single-stranded DNA circles having a predetermined size and nucleotide sequence using pre-designed hairpin oligonucleotides containing complementary sequences for directing ligation to form dumbbell-shaped monomers followed by heat denaturation to yield single-stranded DNA circles.

The present invention provides methods for synthesis and therapeutic use of DNA and RNA oligonucleotides and analogs. RNA oligonucleotides are synthesized using a small, circular DNA template which lacks an RNA polymerase promoter sequence. The RNA synthesis is performed by combining a circular single-stranded oligonucleotide template with an effective RNA polymerase and at least two types of ribonucleotide triphosphate to form an RNA oligonucleotide multimer comprising multiple copies of the desired RNA oligonucleotide sequence. Preferably, the RNA oligonucleotide multimer is cleaved to produce RNA oligonucleotides having well-defined ends. Preferred RNA oligonucleotide multimers contain ribozymes capable of both cis (autolytic) and trans cleavage.

The present invention relates, e.g., to a method for amplifying a small number of copies (e.g. a single copy) of a single-stranded circular DNA molecule (e.g. having a size of about 5-6 kb) by an isothermal rolling circle mechanism, using random or partially random primers and a F29-type DNA polymerase. The method, which can also be used for amplifying DNAs by non-rolling types of multiple displacement amplification, comprises incubating the reaction components in a small volume, e.g. about 10 μl or less, such as about 0.6 μl or less. The degree of amplification can be about 109 fold, or higher. A method for cell-free cloning of DNA, using the rolling circle amplification method of the invention, is described.

A method of juxtaposing sequence tags (GVTs) that are unique positional markers along the length of a population of target nucleic acid molecules is provided, the method comprising: fragmenting the target nucleic acid molecule to form target DNA insert; ligating the target DNA insert to a DNA vector or backbone to create a circular molecule; digesting the target DNA insert endonuclease to cleave the target DNA insert at a distance from each end of the target DNA insert yielding two GVTs comprising terminal sequences of the target DNA insert attached to an undigested linear backbone; recircularizing the linear backbone with the attached GVTs to obtain a circular DNA containing a GVT-pair having two juxtaposed GVTs; and recovering the GVT-pair DNA by nucleic acid amplification or digestion with endonuclease having sites flanking the GVT-pair. Cosmid vectors are provided for creating GVT-pairs of ˜45- to 50-kb separation sequencable by next-generation DNA sequencers.

Compositions and methods for detecting small quantities of analytes such as proteins and polypeptides are disclosed. The method involves linking a primer to an analyte, which is then used to mediate rolling circle replication of circular DNA molecules. The replication of DNA circles is dependent on the presence of primers. Thus, the methods disclosed herein can generate an amplified signal from any analyte of interest by rolling circle replication. The amplified DNA remains attached to the analyte via the primer, allowing stereoscopic detection of the analyte. The methods of the invention can be used to detect and analyze proteins or polypeptides. Various proteins can be analyzed by microarrays to which various proteins are immobilized. Thus, rolling circle replication primers are linked to various proteins using a conjugate of the primer and a molecule capable of specifically binding the protein to be tested. Rolling circle replication of the primers produces a large amount of DNA product at the site in the matrix where the protein is anchored. The amplified DNA serves as a signal for easy detection of the protein. The methods of the invention can also be used to compare proteins expressed in two or more samples. The resulting information is similar to the type of information gathered in nucleic acid expression systems. The method of the present invention can detect and quantify the protein expressed in any cell or tissue sensitively and accurately.

The invention provides improved methods of introducing site-directed mutations into circular DNA molecules of interest by means of mutagenic primer pairs. The mutagenic primer pairs are also selected so as to be either completely complementary or partially complementary to each other, wherein the mutation site (or sites) is located within the region of complementarity. A mutagenic primer pair is annealed to opposite strands of a circular DNA molecule containing the DNA sequence to be mutagenized. After annealing, first and second mutagenized DNA strands, each incorporating a member of the mutagenic oligonucleotide primer pair is synthesized by a linear cyclic amplification reaction. After the linear cyclic amplification mediated synthesis step is completed, the reaction mixture is treated with a selection enzyme that digests the parental template strands. After the digesting step, a double-stranded circular DNA intermediate is formed. The double-stranded circular DNA intermediates is transformed in suitable competent host cells and closed circular double- stranded DNA corresponding to the parental template molecules, but containing the desired mutation or mutations of interest, may be conveniently recovered from the transformed cells. The invention also provide kits for site-directed mutagenesis in accordance with methods of the present invention.