Sun H, Yabuki A, Maizels N
Department of Molecular Biophysics and Biochemistry and Genetics, Yale University School of Medicine, New Haven, CT 06520, USA.
Proc Natl Acad Sci U S A. 2001 Oct 23;98(22):12444-9. doi: 10.1073/pnas.231479198.
We have identified a human nuclease that specifically cleaves four-stranded DNA stabilized by G quartets (G4 DNA). This nuclease, GQN1 (G quartet nuclease 1), cuts within the single-stranded region 5' of the barrel formed by stacked G quartets. GQN1 does not cleave duplex or single-stranded DNA, Holliday junctions, or G4 RNA. Cleavage depends on DNA structure and not on flanking sequence. Activity is elevated in but not restricted to B cells, making GQN1 a strong candidate for function in immunoglobulin heavy chain class switch recombination. Identification of a mammalian nuclease that specifically cleaves G4 DNA provides further support for the notion that DNA structures stabilized by G quartets form in vivo and function in regulated recombination and genomic evolution.
我们鉴定出一种人类核酸酶，它能特异性切割由G-四联体（G4 DNA）稳定的四链DNA。这种核酸酶GQN1（G-四联体核酸酶1）在由堆叠的G-四联体形成的桶状结构5'端的单链区域内进行切割。GQN1不切割双链或单链DNA、霍利迪连接体或G4 RNA。切割取决于DNA结构而非侧翼序列。其活性在B细胞中升高，但不仅限于B细胞，这使得GQN1成为免疫球蛋白重链类别转换重组功能的有力候选者。鉴定出一种特异性切割G4 DNA的哺乳动物核酸酶，为G-四联体稳定的DNA结构在体内形成并在调控重组和基因组进化中发挥作用这一观点提供了进一步支持。
