Hockemeyer Dirk, Palm Wilhelm, Else Tobias, Daniels Jan-Peter, Takai Kaori K, Ye Jeffrey Z-S, Keegan Catherine E, de Lange Titia, Hammer Gary D
Laboratory for Cell Biology and Genetics, The Rockefeller University, 1230 York Avenue, New York, New York 10065, USA.
Nat Struct Mol Biol. 2007 Aug;14(8):754-61. doi: 10.1038/nsmb1270. Epub 2007 Jul 15.
The shelterin complex at mammalian telomeres contains the single-stranded DNA-binding protein Pot1, which regulates telomere length and protects chromosome ends. Pot1 binds Tpp1, the shelterin component that connects Pot1 to the duplex telomeric DNA-binding proteins Trf1 and Trf2. Control of telomere length requires that Pot1 binds Tpp1 as well as the single-stranded telomeric DNA, but it is not known whether the protective function of Pot1 depends on Tpp1. Alternatively, Pot1 might function similarly to the Pot1-like proteins of budding and fission yeast, which have no known Tpp1-like connection to the duplex telomeric DNA. Using mutant mouse cells with diminished Tpp1 levels, RNA interference directed to mouse Tpp1 and Pot1, and complementation of mouse Pot1 knockout cells with human and mouse Pot1 variants, we show here that Tpp1 is required for the protective function of mammalian Pot1 proteins.
哺乳动物端粒处的保护蛋白复合体包含单链DNA结合蛋白Pot1，该蛋白可调节端粒长度并保护染色体末端。Pot1与Tpp1结合，Tpp1是保护蛋白复合体的一个组成部分，它将Pot1与双链端粒DNA结合蛋白Trf1和Trf2相连。端粒长度的调控要求Pot1既能结合Tpp1，又能结合单链端粒DNA，但目前尚不清楚Pot1的保护功能是否依赖于Tpp1。另外，Pot1的功能可能类似于芽殖酵母和裂殖酵母中的Pot1样蛋白，它们与双链端粒DNA不存在已知的类似Tpp1的联系。通过使用Tpp1水平降低的突变小鼠细胞、针对小鼠Tpp1和Pot1的RNA干扰，以及用人和小鼠的Pot1变体对小鼠Pot1基因敲除细胞进行互补实验，我们在此表明，Tpp1是哺乳动物Pot1蛋白发挥保护功能所必需的。
