McConnell Audrey D, Gelbart Marnie E, Tsukiyama Toshio
Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA.
Mol Cell Biol. 2004 Apr;24(7):2605-13. doi: 10.1128/MCB.24.7.2605-2613.2004.
We report the identification of two new subunits of the Isw2 chromatin-remodeling complex in Saccharomyces cerevisiae. Both proteins, Dpb4p and Yjl065cp (named Dls1p), contain histone fold motifs and are homologous to the two smallest subunits of ISWI-containing CHRAC complexes in higher eukaryotes. Dpb4p is also a subunit of the DNA polymerase epsilon (polepsilon) complex, and Dls1p is homologous to another polepsilon subunit, Dpb3p. Therefore, these small histone fold proteins may fulfill functions that are required for both polepsilon and Isw2 complexes. We characterized the role of Dls1p in known roles of the Isw2 complex in vivo. Transcriptional analyses reveal that the Isw2 complex requires Dls1p to various degrees at a wide variety of loci in vivo. Consistent with this, Dls1p is required for Isw2-dependent chromatin remodeling in vivo, although the requirement for this protein varies among Isw2 targets. Dls1p is likely required for functions of the Isw2 complex at steps subsequent to its interaction with chromatin, since a dls1 mutation does not affect cross-linking of Isw2 with chromatin.
我们报告了在酿酒酵母中鉴定出Isw2染色质重塑复合物的两个新亚基。这两种蛋白质，Dpb4p和Yjl065cp（命名为Dls1p），都含有组蛋白折叠基序，并且与高等真核生物中含ISWI的CHRAC复合物的两个最小亚基同源。Dpb4p也是DNA聚合酶ε（polepsilon）复合物的一个亚基，并且Dls1p与另一个polepsilon亚基Dpb3p同源。因此，这些小的组蛋白折叠蛋白可能履行polepsilon和Isw2复合物都需要的功能。我们在体内表征了Dls1p在Isw2复合物已知功能中的作用。转录分析表明，Isw2复合物在体内的各种位点在不同程度上需要Dls1p。与此一致的是，虽然Isw2靶标对该蛋白质的需求各不相同，但Dls1p在体内Isw2依赖性染色质重塑中是必需的。Dls1p可能在Isw2复合物与染色质相互作用后的步骤中发挥作用，因为dls1突变不影响Isw2与染色质的交联。
