Structure-based mutagenesis of SigE verifies the importance of hydrophobic and electrostatic residues in type III chaperone function
Structure-based mutagenesis of SigE verifies the importance of hydrophobic and electrostatic residues in type III chaperone function
复制标题
DOI：
10.1111/j.1365-2958.2006.05418.x
复制
发表时间：
2006-11-01
影响因子：
3.6
通讯作者：
Steele-Mortimer, Olivia
中科院分区：
文献类型：
--
作者：
Knodler, Leigh A.;Bertero, Michela;Steele-Mortimer, Olivia
尽管几乎没有序列同一性，但大多数 III 型伴侣显示出类似的同源二聚体结构，其特征是负电荷广泛分布在其整个表面上，并散布有疏水斑块。在这里，我们使用沙门氏菌的 SigE 作为 IA 类 III 型伴侣的模型，以研究这些表面暴露残基在伴侣功能中的作用。 SigE 对于其同源效应子 SopB (SigD) 的稳定性、分泌和易位至关重要。我们分析了 SigE 九个保守的疏水性和电负性表面暴露氨基酸的突变对 SopB 结合、稳定性、分泌和易位的影响。其中 6 个突变影响了 SigE 功能的某些方面（Leu14、Asp20、Leu22、Leu23、Ile25 和 Asp51），另外 3 个突变没有影响（Leu54、Glu92 和 Glu99）。我们的结果强调，疏水性和电负性表面都是 SigE 功能所必需的，并为预测其他伴侣效应器对的侧链需求提供了重要基础。
Despite sharing little sequence identity, most type III chaperones display a similar homodimeric structure characterized by negative charges distributed broadly over their entire surface, interspersed with hydrophobic patches. Here we have used SigE from Salmonella as a model for class IA type III chaperones to investigate the role of these surface-exposed residues in chaperone function. SigE is essential for the stability, secretion and translocation of its cognate effector, SopB (SigD). We analysed the effect of mutating nine conserved hydrophobic and electronegative surface-exposed amino acids of SigE on SopB binding, stability, secretion and translocation. Six of these mutations affected some aspect of SigE function (Leu14, Asp20, Leu22, Leu23, Ile25 and Asp51) and three were without effect (Leu54, Glu92 and Glu99). Our results highlight that both hydrophobic and electronegative surfaces are required for the function of SigE and provide an important basis for the prediction of side-chain requirements for other chaperone-effector pairs.