Xie W, Gai X, Zhu Y, Zappulla D C, Sternglanz R, Voytas D F
Department of Zoology and Genetics, Iowa State University, Ames, Iowa 50011-3260, USA.
Mol Cell Biol. 2001 Oct;21(19):6606-14. doi: 10.1128/MCB.21.19.6606-6614.2001.
The Ty5 retrotransposons of Saccharomyces cerevisiae integrate preferentially into regions of silent chromatin at the telomeres and silent mating loci (HMR and HML). We define a Ty5-encoded targeting domain that spans 6 amino acid residues near the C terminus of integrase (LXSSXP). The targeting domain establishes silent chromatin when it is tethered to a weakened HMR-E silencer, and it disrupts telomeric silencing when it is overexpressed. As determined by both yeast two-hybrid and in vitro binding assays, the targeting domain interacts with the C terminus of Sir4p, a structural component of silent chromatin. This interaction is abrogated by mutations in the targeting domain that disrupt integration into silent chromatin, suggesting that recognition of Sir4p by the targeting domain is the primary determinant in Ty5 target specificity.
酿酒酵母的Ty5逆转座子优先整合到端粒和沉默交配位点（HMR和HML）的沉默染色质区域。我们定义了一个Ty5编码的靶向结构域，它位于整合酶C末端附近的6个氨基酸残基处（LXSSXP）。当该靶向结构域与弱化的HMR - E沉默子相连时可建立沉默染色质，而当它过度表达时则会破坏端粒沉默。通过酵母双杂交和体外结合试验确定，该靶向结构域与Sir4p的C末端相互作用，Sir4p是沉默染色质的一种结构成分。靶向结构域中破坏整合到沉默染色质中的突变消除了这种相互作用，这表明靶向结构域对Sir4p的识别是Ty5靶标特异性的主要决定因素。
