Effect of conserved intersubunit amino acid substitutions on Hfq protein structure and stability
Effect of conserved intersubunit amino acid substitutions on Hfq protein structure and stability
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DOI：
10.1134/s0006297914050113
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发表时间：
2014-05-01
影响因子：
2.8
通讯作者：
Nikulin, A. D.
中科院分区：
文献类型：
--
作者：
Murina, V. N.;Melnik, B. S.;Nikulin, A. D.
HFQ是一种耐热的与RNA结合的细菌蛋白，形成一种形状独特的同源六聚体。根据序列和结构的相似性，Hfq属于LIKE-Sm(LSM)蛋白家族。尽管古生物和真核生物的LSM蛋白有很高的同源性，但它们的四级结构不同，通常由五到八个单体组成。在这项工作中，验证了保守的亚基间氢键对Hfq空间组织的重要性。测定了Gln8Ala、Asn28Ala、Asp40Ala和Tyr55Ala Hfq突变体的结构和稳定性。所有这些蛋白质都有相同的六聚体结构，但它们的稳定性不同。由于Gln8Ala、Asp40Ala和Tyr55Ala取代导致单个亚基间氢键的消除，导致Hfq六聚体的稳定性降低。Tyr55Ala Hfq以及之前研究的His57Ala Hfq降低了蛋白质的热稳定性，这似乎对应于蛋白质疏水核心的打开。
Hfq is a thermostable RNA-binding bacterial protein that forms a uniquely shaped homohexamer. Based on sequence and structural similarity, Hfq belongs to the like-Sm (LSm) protein family. In spite of a rather high degree of homology between archaeal and eukaryotic LSm proteins, their quaternary structure is different, usually consisting of five to eight monomers. In this work, the importance of conserved intersubunit hydrogen bonds for the Hfq spatial organization was tested. The structures and stabilities for the Gln8Ala, Asn28Ala, Asp40Ala, and Tyr55Ala Hfq mutants were determined. All these proteins have the same hexamer organization, but their stability is different. Elimination of a single intersubunit hydrogen bond due to Gln8Ala, Asp40Ala, and Tyr55Ala substitutions results in decreased stability of the Hfq hexamer. Tyr55Ala Hfq as well as the earlier studied His57Ala Hfq has reduced protein thermostability, which seems to correspond to an opening of the protein hydrophobic core.