Blanca Giuseppina, Villani Giuseppe, Shevelev Igor, Ramadan Kristijan, Spadari Silvio, Hübscher Ulrich, Maga Giovanni
Institut de Pharmacologie et de Biologie Structurale, Centre National de la Recherche Scientifique, 205 route de Narbonne, 31077 Toulouse Cedex, France.
Biochemistry. 2004 Sep 14;43(36):11605-15. doi: 10.1021/bi049050x.
Human DNA polymerases (pols) beta and lambda could promote template slippage and generate -1 frameshifts on defined heteropolymeric DNA substrates containing a single abasic site. Kinetic data demonstrated that pol lambda was more efficient than pol beta in catalyzing translesion DNA synthesis past an abasic site, particularly in the presence of low nucleotide concentrations. Moreover, pol lambda was found to generate frameshifts in two ways: first, by using a nucleotide-stabilized primer misalignment mechanism, or second, by promoting primer reannealing using microhomology regions between the terminal primer sequence and the template strand. Our results suggest a molecular mechanism for the observed high in vivo rate of frameshifts generation by pol lambda and highlight the remarkable ability of pol lambda to promote microhomology pairing between two DNA strands, further supporting its proposed role in the nonhomologous end joining process.
人类DNA聚合酶（pols）β和λ可促进模板滑动，并在含有单个无碱基位点的特定异聚DNA底物上产生-1移码突变。动力学数据表明，在催化无碱基位点后的跨损伤DNA合成时，聚合酶λ比聚合酶β更有效，尤其是在低核苷酸浓度存在的情况下。此外，发现聚合酶λ通过两种方式产生移码突变：第一，通过使用核苷酸稳定的引物错配机制；第二，通过利用末端引物序列与模板链之间的微同源区域促进引物重新退火。我们的结果提示了一种分子机制，用于解释聚合酶λ在体内观察到的高移码突变率，并突出了聚合酶λ促进两条DNA链之间微同源配对的显著能力，进一步支持了其在非同源末端连接过程中所提出的作用。
