Inorganic pyrophosphatase is a component of the Drosophila nucleosome remodeling factor complex
Inorganic pyrophosphatase is a component of the Drosophila nucleosome remodeling factor complex
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DOI：
10.1101/gad.12.20.3206
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发表时间：
1998-10-15
影响因子：
10.5
通讯作者：
Wu, C
中科院分区：
文献类型：
--
作者：
Gdula, DA;Sandaltzopoulos, R;Wu, C
果蝇核小体重塑因子(NURF)是一种由四种多肽组成的蛋白质复合体，在体外以ATP依赖的方式促进染色质结构的扰动。140 kD的NURF亚基模拟开关(ISWI)与SWI2/SNF2 ATPase相关。另一个亚基NURF-55是一个55kD的WD重复蛋白，与人视网膜母细胞瘤相关蛋白RbAp48同源。在这里，我们报道了NURF最小(38kD)组分的克隆和鉴定。NURF-38与已知的无机焦磷酸酶有惊人的同源性。单独的重组NURF 38和纯化的NURF复合体都具有无机焦磷酸酶活性。氟化钠抑制NURF的焦磷酸酶活性对染色质重塑无明显影响，提示这两种活性可能是生化解偶联的。我们的结果表明，NURF-38可能在复合体中发挥结构或调节作用。或者，由于在核苷酸掺入过程中未水解性焦磷酸的积累抑制了聚合，NURF也可能被适应于通过有效地去除抑制代谢物而将焦磷酸酶递送到染色质以辅助复制或转录。
The Drosophila nucleosome remodeling factor (NURF) is a protein complex consisting of four polypeptides that facilitates the perturbation of chromatin structure in vitro in an ATP-dependent manner. The 140-kD NURF subunit, imitation switch (ISWI), is related to the SWI2/SNF2 ATPase. Another subunit, NURF-55, is a 55-kD WD repeat protein homologous to the human retinoblastoma-associated protein RbAp48. Here, we report the cloning and characterization of the smallest (38 kD) component of NURF. NURF-38 is strikingly homologous to known inorganic pyrophosphatases. Both recombinant NURF 38 alone and the purified NURF complex are shown to have inorganic pyrophosphatase activity. Inhibition of the pyrophosphatase activity of NURF with sodium fluoride has no significant effect on chromatin remodeling, indicating that these two activities may be biochemically uncoupled. Our results suggest that NURF-38 may serve a structural or regulatory role in the complex. Alternatively, because accumulation of unhydrolyzed pyrophosphate during nucleotide incorporation inhibits polymerization, NURF may also have been adapted to deliver pyrophosphatase to chromatin to assist in replication or transcription by efficient removal of the inhibitory metabolite.