Disulfide bond of Mycoplasma pneumoniae community-acquired respiratory distress syndrome toxin is essential to maintain the ADP-ribosylating and vacuolating activities
Disulfide bond of Mycoplasma pneumoniae community-acquired respiratory distress syndrome toxin is essential to maintain the ADP-ribosylating and vacuolating activities
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DOI：
10.1111/cmi.13032
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发表时间：
2019-08-01
影响因子：
3.4
通讯作者：
Kannan, Thirumalai R.
中科院分区：
文献类型：
--
作者：
Balasubramanian, Sowmya;Pandranki, Lavanya;Kannan, Thirumalai R.
肺炎支原体是美国和全球住院儿童中细菌性社区获得性肺炎的主要原因。社区获得性呼吸窘迫综合征（ARDS）毒素是肺炎支原体的关键毒力决定因子。肺炎。该毒素的N-末端具有ADP-核糖基转移酶（ADPRT）活性，C-末端具有结合和空泡化活性。用烷化剂对野生型（WT）和半胱氨酸-丝氨酸突变的BMPT毒素进行巯基捕获实验，发现在氨基末端半胱氨酸残基C230和C247处形成二硫键。与WT和其他突变毒素相比，C247 S不稳定，不能用于比较研究。尽管WT和突变毒素的结合、进入和逆行运输模式没有显著变化，但C230 S未引起中毒细胞中空泡形成。此外，与WT毒素相比，C230 S的ADPRT结构域对所有测试的蛋白酶更敏感。尽管具有体外ADPRT活性，但在U937细胞中C230 S毒素介导的ADPRT活性相关的IL-1 β产生减少，以及C230 S蛋白酶释放羧基区域的空泡形成活性恢复，表明二硫键不仅对维持ADPRT毒素的构象稳定性至关重要，而且对正确执行其细胞病变效应至关重要。
Mycoplasma pneumoniae is the leading cause of bacterial community-acquired pneumonia among hospitalised children in United States and worldwide. Community-acquired respiratory distress syndrome (CARDS) toxin is a key virulence determinant of M. pneumoniae. The N-terminus of CARDS toxin exhibits ADP-ribosyltransferase (ADPRT) activity, and the C-terminus possesses binding and vacuolating activities. Thiol-trapping experiments of wild-type (WT) and cysteine-to-serine-mutated CARDS toxins with alkylating agents identified disulfide bond formation at the amino terminal cysteine residues C230 and C247. Compared with WT and other mutant toxins, C247S was unstable and unusable for comparative studies. Although there were no significant variations in binding, entry, and retrograde trafficking patterns of WT and mutated toxins, C230S did not elicit vacuole formation in intoxicated cells. In addition, the ADPRT domain of C230S was more sensitive to all tested proteases when compared with WT toxin. Despite its in vitro ADPRT activity, the reduction of C230S CARDS toxin-mediated ADPRT activity-associated IL-1 beta production in U937 cells and the recovery of vacuolating activity in the protease-released carboxy region of C230S indicated that the disulfide bond was essential not only to maintain the conformational stability of CARDS toxin but also to properly execute its cytopathic effects.