The length of the sgRNA-DNA complementary sequence is a key factor influencing the cleavage activity of Streptococcus pyogenes Cas9(SpCas9)and its variants.The detailed mechanism remains unknown.Here,based on in vitro...The length of the sgRNA-DNA complementary sequence is a key factor influencing the cleavage activity of Streptococcus pyogenes Cas9(SpCas9)and its variants.The detailed mechanism remains unknown.Here,based on in vitro cleavage assays and base editing analysis,we demonstrate that reducing the length of this complementary region can confer nickase activity on SpCas9 and eSpCas9(1.1).We also show that these nicks are made on the target DNA strand.These properties encouraged us to develop a dual-functional system that simultaneously carries out double-strand DNA cleavage and C-to-T base conversions at separate targets.This system provides a novel tool for achieving trait stacking in plants.展开更多
We developed a nicking endonuclease dependent DNA amplification (NDA), using Nt.BstNBI to catalyze single-stranded nick on double-stranded DNA, and Bst DNA polymerase to make extension while sealing the nick and displ...We developed a nicking endonuclease dependent DNA amplification (NDA), using Nt.BstNBI to catalyze single-stranded nick on double-stranded DNA, and Bst DNA polymerase to make extension while sealing the nick and displacing the downstream strand. The displaced single-stranded DNA thereby serves as template for primers hybridization and extension, resulting in exponential synthesis of target DNA under isothermal condition. Over 105 folds target DNA amplification can be achieved in 30 minutes, generating DNA product suitable for both diagnosis and DNA cloning. This NDA strategy does not require thermal cycling or prerequisite nucleotides modification, making it suitable for application in the field and at the point-of-care.展开更多
基金supported by grants from the Strategic Priority Research Program of the Chinese Academy of Sciences(Precision Seed Design and Breeding,XDA24020102)the National Transgenic Science and Technology Program(2018ZX0801002B)+2 种基金the National Natural Science Foundation of China(31788103 and 31971370)the Chinese Academy of Sciences(QYZDY-SSW-SMC030)the National Key R&D Program of China(2018YFA0900600,2016YFD0100102-11,and 2016YFD0100605)。
文摘The length of the sgRNA-DNA complementary sequence is a key factor influencing the cleavage activity of Streptococcus pyogenes Cas9(SpCas9)and its variants.The detailed mechanism remains unknown.Here,based on in vitro cleavage assays and base editing analysis,we demonstrate that reducing the length of this complementary region can confer nickase activity on SpCas9 and eSpCas9(1.1).We also show that these nicks are made on the target DNA strand.These properties encouraged us to develop a dual-functional system that simultaneously carries out double-strand DNA cleavage and C-to-T base conversions at separate targets.This system provides a novel tool for achieving trait stacking in plants.
文摘We developed a nicking endonuclease dependent DNA amplification (NDA), using Nt.BstNBI to catalyze single-stranded nick on double-stranded DNA, and Bst DNA polymerase to make extension while sealing the nick and displacing the downstream strand. The displaced single-stranded DNA thereby serves as template for primers hybridization and extension, resulting in exponential synthesis of target DNA under isothermal condition. Over 105 folds target DNA amplification can be achieved in 30 minutes, generating DNA product suitable for both diagnosis and DNA cloning. This NDA strategy does not require thermal cycling or prerequisite nucleotides modification, making it suitable for application in the field and at the point-of-care.
