Autoproteolysis of YscU of Yersinia pseudotuberculosis Is Important for Regulation of Expression and Secretion of Yop Proteins
Autoproteolysis of YscU of Yersinia pseudotuberculosis Is Important for Regulation of Expression and Secretion of Yop Proteins
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DOI：
10.1128/jb.01730-08
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发表时间：
2009-07-01
影响因子：
3.2
通讯作者：
Wolf-Watz, Hans
中科院分区：
文献类型：
--
作者：
Bjornfot, Ann-Catrin;Lavander, Moa;Wolf-Watz, Hans
耶尔森氏菌的YscU可以被自蛋白水解以产生命名为YscU（CC）的10-kDa C-末端多肽。自身蛋白水解发生在YscU的保守的N向下箭头PTH基序处。发现特异性的反顺式点突变体N263 A和P264 A在蛋白质水解方面存在缺陷。这两种突变体在含钙培养基（+Ca 2+条件）和钙耗尽培养基（-Ca 2+条件）中表达和分泌Yop蛋白（Yops）。N263 A突变株的Yop和LcrV分泌水平约为野生型菌株的20%，但不同分泌的Yop（包括LcrV）的比例没有显著差异。无论培养基中的钙浓度如何，N263 A突变体都分泌LcrQ，证实了突变体在含Ca 2+的培养基中表达和分泌Yops的观察结果。YscF，III型分泌系统（T3 SS）针蛋白，分泌水平升高的突变体相比，野生型细菌生长在+Ca 2+条件下。YscF分泌诱导的突变体，以及在野生型，当细菌孵育下-Ca 2+的条件下，虽然突变体分泌少量的YscF。N263 A突变体对HeLa细胞具有细胞毒性，表明T3 SS介导的效应子递送是功能性的。我们认为，YSCU块YOP释放和自蛋白水解是必需的，以减轻这种封锁。
YscU of Yersinia can be autoproteolysed to generate a 10-kDa C-terminal polypeptide designated YscU(CC). Autoproteolysis occurs at the conserved N down arrow PTH motif of YscU. The specific in-cis-generated point mutants N263A and P264A were found to be defective in proteolysis. Both mutants expressed and secreted Yop proteins (Yops) in calcium-containing medium (+Ca2+ conditions) and calcium-depleted medium (-Ca2+ conditions). The level of Yop and LcrV secretion by the N263A mutant was about 20% that of the wild-type strain, but there was no significant difference in the ratio of the different secreted Yops, including LcrV. The N263A mutant secreted LcrQ regardless of the calcium concentration in the medium, corroborating the observation that Yops were expressed and secreted in Ca2+-containing medium by the mutant. YscF, the type III secretion system (T3SS) needle protein, was secreted at elevated levels by the mutant compared to the wild type when bacteria were grown under +Ca2+ conditions. YscF secretion was induced in the mutant, as well as in the wild type, when the bacteria were incubated under -Ca2+ conditions, although the mutant secreted smaller amounts of YscF. The N263A mutant was cytotoxic for HeLa cells, demonstrating that the T3SS-mediated delivery of effectors was functional. We suggest that YscU blocks Yop release and that autoproteolysis is required to relieve this block.