Single-stranded megaprimer splicing through OE-PCR: Construction of full-length Aspergillus niger arginase cDNA.

A useful variant of PCR technique was devised to generate full-length Aspergillus niger arginase cDNA for expression. Briefly, a 450 bp amplicon was first constructed through overlap extension PCR (OE-PCR) by splicing in a 101 nucleotide long single-stranded megaprimer, facilitated by inclusion of an additional, shorter forward primer in the reaction. The amplicon was suitably cloned into pBlueScript to obtain pArg440 and the insert sequenced. The full-length arginase cDNA was subsequently assembled in pArg440 and moved into pET23a for heterologous expression. An interesting feature of this strategy was not to stoichiometrically incorporate the oligonucleotide megaprimer, but use it only as an early template. This OE-PCR strategy to utilize long single-stranded megaprimer may prove handy in terms of efficiency, yield and sequence choice.

Fast and Almost 100% Efficiency Site-directed Mutagenesis by The Megaprimer PCR Method / 生物化学与生物物理进展

A novel PCR-based mutagenesis method was reported, in which there is no need to purify megaprimers or design a special flanking primer. This method used one mutagenic primer and two sequencing primers (T_m≤58℃) as flanking primers. After first round PCR, 12.5 μl first PCR production was directly added into 50 μl second PCR system as template and megaprimer, and 10 rounds of asymmetrical PCR at high temperature of annealing (68 ℃ ) was to add in initiation of second PCR. This additional step greatly has increased the efficiency of mutagenesis via 600 bp or 800 bp long megaprimer. The results demonstrated that this method can achieve high fidelity, 97%～ 98% efficiency, high yield.