Structural characteristics of the plasmid-encoded toxin from enteroaggregative Escherichia coli.
Structural characteristics of the plasmid-encoded toxin from enteroaggregative Escherichia coli.
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来自肠聚集性大肠杆菌的质粒编码毒素的结构特征。
DOI：
10.1021/bi8008714
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发表时间：
2008
期刊：
影响因子：
2.9
通讯作者：
Teter,Ken
中科院分区：
文献类型：
--
作者：
Scaglione,Patricia;Nemec,KathleenN;Burlingame,KaitlinE;Grabon,Agnieszka;Huerta,Jazmin;Navarro-Garcia,Fernando;Tatulian,SurenA;Teter,Ken
肠聚集性大肠杆菌质粒编码毒素（Pet）的中毒需要毒素从内质网（ER）移位到胞质溶胶。该事件涉及ER相关降解（ERAD）的质量控制系统，但该过程的分子细节表征较差。对于许多结构上不同的AB型毒素，ERAD介导的易位是由热不稳定的A链的自发解折叠引发的。在这里，我们表明，宠物，非AB毒素，从事ERAD通过不同的机制，不涉及热展开。圆二色性和荧光光谱测量表明，PET在37 °C下保持其大部分二级和三级结构特征，仅在≥50 °C的温度下发生显著的热去折叠。荧光猝灭实验检测到Pet芳香族氨基酸残基在37 °C下的部分溶剂暴露，并且基于细胞的测定表明这些变化可以激活ERAD相关事件，称为未折叠蛋白质反应。我们还发现，HEp-2细胞与甘油（一种蛋白质稳定剂）一起孵育时对Pet中毒具有抗性。总而言之，我们的数据是一致的ERAD活性的模型，其中触发了一个微妙的结构不稳定的宠物和暴露的宠物疏水残基在生理温度。这进一步得到了计算机建模分析的支持，该分析在Pet中的其他可接近的非极性残基中鉴定了表面暴露的疏水环。从我们的数据看来，宠物可以促进其ERAD介导的易位到胞质溶胶的一个独特的机制，涉及部分暴露的疏水残基，而不是大量的展开观察某些AB毒素。
Intoxication by the plasmid-encoded toxin (Pet) of enteroaggregativeEscherichia colirequires toxin translocation from the endoplasmic reticulum (ER) to the cytosol. This event involves the quality control system of ER-associated degradation (ERAD), but the molecular details of the process are poorly characterized. For many structurally distinct AB-type toxins, ERAD-mediated translocation is triggered by the spontaneous unfolding of a thermally unstable A chain. Here we show that Pet, a non-AB toxin, engages ERAD by a different mechanism that does not involve thermal unfolding. Circular dichroism and fluorescence spectroscopy measurements demonstrated that Pet maintains most of its secondary and tertiary structural features at 37 °C, with significant thermal unfolding only occurring at temperatures ≥50 °C. Fluorescence quenching experiments detected the partial solvent exposure of Pet aromatic amino acid residues at 37 °C, and a cell-based assay suggested that these changes could activate an ERAD-related event known as the unfolded protein response. We also found that HEp-2 cells were resistant to Pet intoxication when incubated with glycerol, a protein stabilizer. Altogether, our data are consistent with a model in which ERAD activity is triggered by a subtle structural destabilization of Pet and the exposure of Pet hydrophobic residues at physiological temperature. This was further supported by computer modeling analysis, which identified a surface-exposed hydrophobic loop among other accessible nonpolar residues in Pet. From our data it appears that Pet can promote its ERAD-mediated translocation into the cytosol by a distinct mechanism involving partial exposure of hydrophobic residues rather than the substantial unfolding observed for certain AB toxins.
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影响因子：
3.6
作者：
Jong, Wouter S. P.;ten Hagen-Jongman, Corinne M.;Luirink, Joen
通讯作者：
Luirink, Joen
影响因子：
2.9
作者：
Deeks, ED;Cook, JP;Lord, JM
通讯作者：
Lord, JM
蛋白质中的芳香族和胱氨酸侧链圆二色性
DOI：
--
发表时间：
1996
期刊：
影响因子：
--
作者：
R. Woody;A. Dunker
通讯作者：
A. Dunker
二甲亚砜可保护细胞免受多肽毒素和脊髓灰质炎病毒的侵害。
DOI：
10.1042/bj2190935
发表时间：
1984
期刊：
The Biochemical journal
影响因子：
--
作者：
K. Sandvig;Helene Madshus;S. Olsnes
通讯作者：
S. Olsnes
DOI：
10.1074/jbc.m003322200
发表时间：
2000-09
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Yan Wang;Jingshi Shen;N. Arenzana;W. Tirasophon;R. Kaufman;R. Prywes
通讯作者：
Yan Wang;Jingshi Shen;N. Arenzana;W. Tirasophon;R. Kaufman;R. Prywes