在減數(shù)分裂和同源DNA修復(fù)中,，會形成一個(gè)被稱為“霍利迪連結(jié)體”（Holliday junction）的四鏈DNA中間體,。這個(gè)結(jié)構(gòu)以共價(jià)鍵方式連接兩個(gè)DNA分子,，因此必須將其拆解,，才能讓染色體正確分離和復(fù)制,。
1991年,，研究人員發(fā)現(xiàn),，大腸桿菌中的ruvC基因的產(chǎn)物為細(xì)菌“霍利迪連結(jié)體”解離酶,。不過，哺乳動物相應(yīng)的酶卻并不好尋找,，但經(jīng)過17年之后,，它們終于被發(fā)現(xiàn)了。人體中的這種酶是一種被稱為GEN1的蛋白,，酵母中的這種酶是其直系同源蛋白,，即Yen 1。二者都是結(jié)構(gòu)特異性核酶的Rad2/XPG家族的成員,。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature 456, 357-361 (20 November 2008) | doi:10.1038/nature07470
Identification of Holliday junction resolvases from humans and yeast
Stephen C. Y. Ip1,3, Ulrich Rass1,3, Miguel G. Blanco1,3, Helen R. Flynn2, J. Mark Skehel2 & Stephen C. West1
1 Genetic Recombination Laboratory,
2 Protein Analysis and Proteomics Laboratory, Cancer Research UK, London Research Institute, Clare Hall Laboratories, South Mimms, Herts EN6 3LD, UK
3 These authors contributed equally to this work.
Abstract
Four-way DNA intermediates, also known as Holliday junctions, are formed during homologous recombination and DNA repair, and their resolution is necessary for proper chromosome segregation. Here we identify nucleases from Saccharomyces cerevisiae and human cells that promote Holliday junction resolution, in a manner analogous to that shown by the Escherichia coli Holliday junction resolvase RuvC. The human Holliday junction resolvase, GEN1, and its yeast orthologue, Yen1, were independently identified using two distinct experimental approaches: GEN1 was identified by mass spectrometry following extensive fractionation of HeLa cell-free extracts, whereas Yen1 was detected by screening a yeast gene fusion library for nucleases capable of Holliday junction resolution. The eukaryotic Holliday junction resolvases represent a new subclass of the Rad2/XPG family of nucleases. Recombinant GEN1 and Yen1 resolve Holliday junctions by the introduction of symmetrically related cuts across the junction point, to produce nicked duplex products in which the nicks can be readily ligated.
