Abstract

The structure and the RNA-binding properties of the Lsm protein from Halobacterium salinarum have been determined. A distinctive feature of this protein is the presence of a short L4 loop connecting the β3 and β4 strands. Since bacterial Lsm proteins (also called Hfq proteins) have a short L4 loop and form hexamers, whereas archaeal Lsm proteins (SmAP) have a long L4 loop and form heptamers, it has been suggested that the length of the L4 loop may affect the quaternary structure of Lsm proteins. Moreover, the L4 loop covers the region of SmAP corresponding to one of the RNA-binding sites in Hfq, and thus can affect the RNA-binding properties of the protein. Our results show that the SmAP from H. salinarum forms heptamers and possesses the same RNA-binding properties as homologous proteins with the long L4 loop. Therefore, the length of the L4 does not govern the number of monomers in the protein particles and does not affect the RNA-binding properties of Lsm proteins.

中文翻译：

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盐生盐杆菌Lsm蛋白的结构和RNA结合特性

摘要

已经确定了来自盐碱杆菌的 Lsm 蛋白的结构和 RNA 结合特性。这种蛋白质的一个显着特征是存在连接 β3 和 β4 链的短 L4 环。由于细菌 Lsm 蛋白（也称为 Hfq 蛋白）具有短 L4 环并形成六聚体，而古细菌 Lsm 蛋白 (SmAP) 具有长 L4 环并形成七聚体，因此有人认为 L4 环的长度可能会影响第四纪Lsm 蛋白的结构。此外，L4 环覆盖了与 Hfq 中 RNA 结合位点之一相对应的 SmAP 区域，因此可以影响蛋白质的 RNA 结合特性。我们的结果表明，来自H. salinarum的 SmAP形成七聚体并具有与具有长 L4 环的同源蛋白质相同的 RNA 结合特性。因此，L4 的长度不控制蛋白质颗粒中单体的数量，也不影响 Lsm 蛋白质的 RNA 结合特性。