Guanine-containing ssDNA and RNA induce dimeric and tetrameric SAMHD1 in cryo-EM and binding studies.
Guanine-containing ssDNA and RNA induce dimeric and tetrameric SAMHD1 in cryo-EM and binding studies.
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在冷冻电镜和结合研究中，含鸟嘌呤的 ssDNA 和 RNA 诱导二聚体和四聚体 SAMHD1。
DOI：
10.1101/2023.06.15.544806
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发表时间：
2023
期刊：
影响因子：
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通讯作者：
Stivers,JamesT
中科院分区：
文献类型：
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作者：
Orris,Benjamin;Sung,MinWoo;Bhat,Shridhar;Xu,Yingrong;Huynh,KevinW;Han,Seungil;Johnson,DarrenC;Bosbach,Benedikt;Shields,DavidJ;Stivers,JamesT
含脱氧核苷三磷酸三磷酸水解酶1（SAMHD 1）的四聚体SAM和HD结构域的dNTP活性在细胞dNTP调节中起关键作用。SAMHD 1还与停滞的DNA复制叉、DNA修复灶、ssRNA和端粒相关。上述功能需要SAMHD 1的核酸结合，这可以通过其寡聚状态来调节。在这里，我们建立了鸟嘌呤特异性A1激活剂位点的每个SAMHD 1单体是用来靶向酶的鸟嘌呤核苷酸内的单链（SS）DNA和RNA。值得注意的是，含有单个鸟嘌呤碱基的核酸链诱导二聚体SAMHD 1，而具有~20个核苷酸间距的两个或更多个鸟嘌呤诱导四聚体形式。ssRNA结合的四聚体SAMHD 1的冷冻电镜结构显示了ssRNA链如何桥接两个SAMHD 1二聚体并稳定结构。这种ssRNA结合的四聚体对于dNTR和RNA酶活性是无活性的。
The dNTPase activity of tetrameric SAM and HD domain containing deoxynucleoside triphosphate triphosphohydrolase 1 (SAMHD1) plays a critical role in cellular dNTP regulation. SAMHD1 also associates with stalled DNA replication forks, DNA repair foci, ssRNA, and telomeres. The above functions require nucleic acid binding by SAMHD1, which may be modulated by its oligomeric state. Here we establish that the guanine-specific A1 activator site of each SAMHD1 monomer is used to target the enzyme to guanine nucleotides within single-stranded (ss) DNA and RNA. Remarkably, nucleic acid strands containing a single guanine base induce dimeric SAMHD1, while two or more guanines with ~20 nucleotide spacing induce a tetrameric form. A cryo-EM structure of ssRNA-bound tetrameric SAMHD1 shows how ssRNA strands bridge two SAMHD1 dimers and stabilize the structure. This ssRNA-bound tetramer is inactive with respect to dNTPase and RNase activity.