The Sac10b homolog from Sulfolobus islandicus is an RNA chaperone
The Sac10b homolog from Sulfolobus islandicus is an RNA chaperone
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来自 Islandicus 硫化叶菌的 Sac10b 同源物是一种 RNA 伴侣
DOI：
10.1093/nar/gkaa656
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发表时间：
2020-09-18
影响因子：
14.9
通讯作者：
Huang，Li
中科院分区：
文献类型：
--
作者：
Zhang，Ningning;Guo，Li;Huang，Li
Sac10b 家族的核酸结合蛋白（也称为 Alba）广泛分布于古细菌中。然而，这些蛋白质的生理作用尚未阐明。在这里，我们发现 Sis10b 是来自超嗜热古菌岛硫化叶菌的 Sac10b 家族的成员，它在 RNA 链交换、体外双链体 RNA 解旋和异源宿主细胞中的 RNA 解折叠中具有活性。与 dsRNA 相比，该蛋白质表现出对 ssRNA 的温度依赖性结合偏好，并且在高温下在 RNA 解旋和 RNA 解折叠中更有效。值得注意的是，Sis10b 中 17 位高度保守的碱性残基 (K) 的丙氨酸取代大大降低了该蛋白催化 RNA 链交换和 RNA 解旋的能力。此外，Sis10b 与 ssRNA 的优先结合还取决于 K17 或 R17 的存在。此外，生长缓慢的 Sis10b 敲低突变体通过过量产生野生型 Sis10b 而不是通过在该突变株中过量产生 K17A 来恢复正常生长。我们的结果表明 Sis10b 是一种 RNA 伴侣，在最适合 S 生长的温度下可能最有效地发挥作用。 islandicus 中，K17 对于该蛋白的伴侣活性至关重要。
Nucleic acid-binding proteins of the Sac10b family, also known as Alba, are widely distributed in Archaea. However, the physiological roles of these proteins have yet to be clarified. Here, we show that Sis10b, a member of the Sac10b family from the hyperthermophilic archaeonSulfolobus islandicus, was active in RNA strand exchange, duplex RNA unwindingin vitroand RNA unfolding in a heterologous host cell. This protein exhibited temperature-dependent binding preference for ssRNA over dsRNA and was more efficient in RNA unwinding and RNA unfolding at elevated temperatures. Notably, alanine substitution of a highly conserved basic residue (K) at position 17 in Sis10b drastically reduced the ability of this protein to catalyse RNA strand exchange and RNA unwinding. Additionally, the preferential binding of Sis10b to ssRNA also depended on the presence of K17 or R17. Furthermore, normal growth was restored to a slow-growing Sis10b knockdown mutant by overproducing wild-type Sis10b but not by overproducing K17A in this mutant strain. Our results indicate that Sis10b is an RNA chaperone that likely functions most efficiently at temperatures optimal for the growth ofS. islandicus, and K17 is essential for the chaperone activity of the protein.