Abstract: The present invention relates to compositions and methods employing 5?-phosphate-dependent nucleic acid exonucleases. In particular, the present invention provides kits and methods employing 5?-phosphate-dependent nucleic acid exonucleases for selective enrichment, isolation and amplification of a particular set of desired nucleic acid molecules from samples that also contain undesired nucleic acid molecules for a variety of uses. In preferred embodiments, the desired nucleic acid molecules comprise prokaryotic and/or eukaryotic mRNA.

Abstract: It can be difficult to achieve efficient transformation of many strains of bacterial cells due in part to the presence of one or more restriction and modification (R-M) systems in the cells that restricts unmodified transforming DNA. Phage T7 OCR protein is a potent inhibitor of Type I R-M systems. Methods are disclosed for improving transformation efficiency of Eubacterial and Archaebacterial cells having an R-M system by introducing into the cells an inhibitor of the restriction activity. For example, addition of 1–5 micrograms of T7 OCR protein to 50 microliters of electrocompetent cells having a Type I R-M system prior to electroporation significantly increased transformation efficiency by unmodified plasmids, fosmid clones, and artificial transposons comprising synaptic complexes.

Abstract: Methods, compositions and kits are disclosed for obtaining directionally truncated polypeptides by inserting a transposon. Preferably the transposon comprises a selectable marker and an ori, and optionally a promoter, a ribosome binding site and a translation start codon, into a target sequence in vitro or in vivo. Amplification products, varying in length depending on the transposon insertion site, are obtained using one primer that anneals to the target sequence and a second primer that anneals to the transposon. Amplification products are ligated to circular dsDNA, transformed into host cells, and individual colonies, each containing a directionally truncated clone of the target sequence, are obtained by plating on medium for which the selectable marker encodes resistance. Directionally truncated polypeptides encoded by the target sequence are obtained in vivo by inducing an RNAP in the host cells that uses the promoter or, in vitro by cell-free transcription and translation.

Abstract: A method for synthesizing a nucleic acid molecule comprising at least one non-canonical nucleoside triphosphate using a mutant polymerase having a reduced discrimination between canonical and non-canonical substrates is disclosed. The method comprises incubating a template nucleic acid in a reaction mixture comprising the mutant nucleic acid polymerase and the appropriate canonical and non-canonical nucleoside triphosphates which are desired substrates for the mutant nucleic acid polymerase. The present invention is also a method of determining the sequence of a nucleic acid molecule using the mutant polymerase to create a nucleic acid molecule comprising at least one non-canonical nucleoside triphosphate.

Abstract: Methods and compositions are provided for assaying for a target analyte in a sample by formation of a substrate for a replicase. The target analyte, if present in the sample, is first bound to a reporter probe. The reporter probe comprises a first portion and a second portion. The first portion comprises a polynucleotide that encodes at least part of a sequence for an RNA that is a substrate for replication. The second portion comprises a molecule that has affinity for an analyte. The reporter probe itself is not a substrate for a replicase. However, a replicase substrate is generated by treating reporter probe which is bound to analyte with a composition having nuclease activity in order to release the parts of the first portion, and then the released parts and one or more mononucleotides or oligonucleotides comprising missing parts of the substrate sequence are joined with a composition having ligase activity.

Abstract: A method of characterizing a nucleic acid molecule is disclosed. The method comprises synthesizing DNA in the presence of a reaction mixture comprising a nucleic acid template, a primer molecule, an enzyme that extends the primer so that a DNA molecule may be synthesized, four canonical deoxynucleoside triphosphates and at least one non-canonical deoxynucleoside triphosphate. The non-canonical deoxynucleoside triphosphate is incorporated into the synthesized DNA in place of a portion of only one canonical deoxynucleoside triphosphate. The synthesized DNA is treated with an N-glycosylase that excises a base portion of the non-canonical deoxynucleoside triphosphate from the synthesized DNA. The DNA is then treated in such a manner that the phosphodiester backbone of the DNA is broken at the abasic site, thus creating at least two DNA fragments. The fragments are separated according to size.

Abstract: A method for synthesizing a nucleic acid molecule comprising at least one non-canonical nucleoside triphosphate using a mutant polymerase having a reduced discrimination between canonical and non-canonical substrates is disclosed. The method comprises incubating a template nucleic acid in a reaction mixture comprising the mutant nucleic acid polymerase and the appropriate canonical and non-canonical nucleoside triphosphates which are desired substrates for the mutant nucleic acid polymerase. The present invention is also a method of determining the sequence of a nucleic acid molecule using the mutant polymerase to create a nucleic acid molecule comprising at least one non-canonical nucleoside triphosphate.

Abstract: A method of analyzing a DNA molecule is disclosed. In one embodiment the method comprises the steps of exposing a DNA molecule to an effective amount of a chemical modification reagent wherein the reagent converts guanine to 8-hydroxyguanine. The oxidized product is then exposed to a DNA glycosylase enzyme and the DNA molecule is cleaved at the site of the 8-hydroxyguanine. The fragments are then resolved by electrophoresis and the position of guanine residues within the DNA molecule is determined. In a preferred embodiment of the present invention, the modification reagent is a thiazine dye and the enzyme is FPG protein.

Abstract: A method of improving the synthesis of full-length cDNA transcripts by Mn.sup.++ -dependent reverse transcriptases, preferably DNA-dependent DNA polymerases, is disclosed.

Abstract: A method for synthesizing a nucleic acid molecule comprising at least one non-canonical nucleoside triphosphate using a mutant polymerase having a reduced discrimination between canonical and non-canonical substrates is disclosed. The method comprises incubating a template nucleic acid in a reaction mixture comprising the mutant nucleic acid polymerase and the appropriate canonical and non-canonical nucleoside triphosphates which are desired substrates for the mutant nucleic acid polymerase. The present invention is also a method of determining the sequence of a nucleic acid molecule using the mutant polymerase to create a nucleic acid molecule comprising at least one non-canonical nucleoside triphosphate.

Abstract: An essentially pure preparation of thermostable RNase H isolated from Thermus flavus is disclosed. In one preferable form of the invention, the RNase H is capable of biological activity after incubation at temperatures equal to or greater than 70.degree. C. for at least ten minutes. The present invention is also a method of digesting RNA polymers that are in duplex form with a DNA molecule. The method comprises exposing the duplex to the isolated thermostable RNase H. The present invention is also a genetic construct capable of expressing a thermostable RNase H.

Abstract: An essentially pure preparation of thermostable RNase H isolated from Thermus flavus is disclosed. In one preferable form of the invention, the RNase H is capable of biological activity after incubation at temperatures equal to or greater than 70.degree. C. for at least ten minutes. The present invention is also a method of digesting RNA polymers that are in duplex form with a DNA molecule. The method comprises exposing the duplex to the isolated thermostable RNase H. The present invention is also a genetic construct capable of expressing a thermostable RNase H.

Abstract: A substantially pure preparation of thermostable RNase H is disclosed. In one preferable form of the invention, the RNase H is capable of biological activity after incubation at temperatures equal to or greater than 70.degree. C. for at least ten minutes. In another preferable form of the invention, the purification is from Thermus thermophilus or a closely related organism. The present invention is also a method of digesting RNA polymers that are in duplex form with a DNA molecule. The method comprises exposing the duplex to the isolated thermostable RNase H.