We present a method in which noncontinuously binding (loop-out) primers are used to exclude regions of DNA that typically interfere with PCR amplification and/or analysis by Sanger sequencing. Several scenarios were tested using this design principle, including M13-tagged PCR primers, non-M13-tagged PCR primers, and sequencing primers. With this technique, a single oligonucleotide is designed in two segments that flank, but do not include, a short region of problematic DNA sequence. During PCR amplification or sequencing, the problematic region is looped-out from the primer binding site, where it does not interfere with the reaction. Using this method, we successfully excluded regions of up to 46 nucleotides. Loop-out primers were longer than traditional primers (27 to 40 nucleotides) and had higher melting temperatures. This method allows the use of a standardized PCR protocol throughout an assay, keeps the number of PCRs to a minimum, reduces the chance for laboratory error, and, above all, does not interrupt the clinical laboratory workflow.
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http://dx.doi.org/10.1016/j.jmoldx.2014.04.005 | DOI Listing |
Nat Struct Mol Biol
April 2015
Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA.
All DNA replicases achieve high fidelity by a conserved mechanism, but each translesion polymerase carries out mutagenic DNA synthesis in its own way. Here we report crystal structures of human DNA polymerase ν (Pol ν), which is homologous to high-fidelity replicases yet is error prone. Instead of a simple open-to-closed movement of the O helix upon binding of a correct incoming nucleotide, Pol ν has a different open state and requires the finger domain to swing sideways and undergo both opening and closing motions to accommodate the nascent base pair.
View Article and Find Full Text PDFJ Mol Diagn
September 2014
ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, Utah; Department of Pathology, University of Utah, Salt Lake City, Utah. Electronic address:
We present a method in which noncontinuously binding (loop-out) primers are used to exclude regions of DNA that typically interfere with PCR amplification and/or analysis by Sanger sequencing. Several scenarios were tested using this design principle, including M13-tagged PCR primers, non-M13-tagged PCR primers, and sequencing primers. With this technique, a single oligonucleotide is designed in two segments that flank, but do not include, a short region of problematic DNA sequence.
View Article and Find Full Text PDFJ Biol Chem
March 2007
Department of Biochemistry, the Ohio State Biochemistry Program, the Comprehensive Cancer Center, Ohio State University, Columbus 43210, USA.
The 3 million-base pair genome of Sulfolobus solfataricus likely undergoes depurination/depyrimidination frequently in vivo. These unrepaired abasic lesions are expected to be bypassed by Dpo4, the only Y-family DNA polymerase from S. solfataricus.
View Article and Find Full Text PDFMol Diagn
September 1998
Molecular Genetics Laboratory, Children's Mercy Hospital, Kansas City, Missouri
Background: The I1307K (T3920 --> A) variant of the APC gene has been identified as a potential risk factor for colorectal cancer and is present in 6% of Ashkenazi Jews. Screening for this mutation may allow identification of people at elevated risk who would benefit from increased surveillance. Methods and Results: We designed an assay to detect the T3920 --> A allele using a primer mismatched at the 3 < 9 terminal nucleotide in the polymerase chain reaction (PCR) to generate a recognition site for the restriction enzyme Mse I.
View Article and Find Full Text PDFBiochim Biophys Acta
September 1996
Department of Neurology, Columbia University, New York, NY 10032, USA.
The use of PCR to identify mtDNAs containing a partial duplication (dup-mtDNA) in the presence of a heteroplasmic population of mtDNAs harboring the corresponding deletion (delta-mtDNA) leads to ambiguous results: when the primers anneal in the duplicated portion of the dup-mtDNA (which is also the non-deleted region of the delta-mtDNA) and point towards the abnormal breakpoint junction, both templates are amplified indiscriminately. We have developed two different 'long PCR' approaches to amplify dup-mtDNA even in the presence of delta-mtDNA and wild-type mtDNA (wt-mtDNA). Long PCR with two primers annealing in the non-duplicated region in dup-mtDNA (equivalent to the region missing in delta-mtDNA) and whose 3' ends pointed towards the duplicated area amplified both dup-mtDNA and coexisting wt-mtDNA.
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