title: Simultaneous amplification and screening of whole plasmids using the T7 bacteriophage replisome.
abstract: This study describes a novel helicase-mediated isothermal DNA amplification method that exponentially amplifies circular DNAs. The circular helicase-dependent amplification (cHDA) system is based on the T7 replication machinery, which includes the processive T7 helicase, an exonuclease-deficient T7 DNA polymerase (T7 Sequenase) and the T7 Gp2.5 single-stranded DNA-binding (SSB) protein. After the duplex DNA template is unwound by the T7 helicase, specific primers anneal to the separated DNA strands and T7 Sequenase extends the 3' end of each primer by a rolling circle mechanism to amplify not only a region defined by the primers but also continuous concatemers of the template. The cHDA reaction can be carried out at one temperature (25 degrees C) for the entire process and can achieve up to 10 000-fold amplification. Amplification can be performed using purified plasmid DNA or a crude cell lysate and can amplify inserts as large as 10 kb. Following a cHDA reaction, the amplified products can be used directly for sequencing and restriction enzyme digestion without further purification. By utilizing the helicase enzyme, circular DNA samples can be simultaneously screened and amplified at one constant temperature in one easy step.
authors.affiliation: BioHelix Corporation, 32 Tozer Road, Beverly, MA 01915, USA.
authors.forename: Yan
authors.initials: Y
authors.lastname: Xu
authors.forename: Hyun-jin
authors.initials: HJ
authors.lastname: Kim
authors.forename: Ann
authors.initials: A
authors.lastname: Kays
authors.forename: Jared
authors.initials: J
authors.lastname: Rice
authors.forename: Huimin
authors.initials: H
authors.lastname: Kong
mesh_terms: D017123:Bacteriophage T7 / Q000235:genetics*; D004265:DNA Helicases / Q000378:metabolism*; D019915:DNA Primase / Q000378:metabolism; D017931:DNA Primers; D004261:DNA Replication; D004262:DNA Restriction Enzymes / Q000378:metabolism; D004270:DNA, Circular / Q000096:biosynthesis*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000378:metabolism*; D021141:Nucleic Acid Amplification Techniques / Q000379:methods*; D010957:Plasmids / Q000096:biosynthesis*; D017422:Sequence Analysis, DNA; D013698:Templates, Genetic; D014764:Viral Proteins / Q000378:metabolism; D000099272:Replisomes
chemical_list: D004265:DNA Helicases; D019915:DNA Primase; D017931:DNA Primers; D004262:DNA Restriction Enzymes; D004270:DNA, Circular; D004268:DNA-Binding Proteins; D004259:DNA-Directed DNA Polymerase; D009097:Multienzyme Complexes; D014764:Viral Proteins; D000099272:Replisomes; C085913:gene 2.5 protein, Enterobacteria phage T7; C034970:bacteriophage T7 induced DNA polymerase