Paharik Alexandra E, Salgado-Pabon Wilmara, Meyerholz David K, White Mark J, Schlievert Patrick M, Horswill Alexander R
Department of Microbiology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.
Department of Pathology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.
mSphere. 2016 Oct 12;1(5). doi: 10.1128/mSphere.00208-16. eCollection 2016 Sep-Oct.
The Spl proteases are a group of six serine proteases that are encoded on the νSaβ pathogenicity island and are unique to . Despite their interesting biochemistry, their biological substrates and functions in virulence have been difficult to elucidate. We found that an operon mutant of the community-associated methicillin-resistant USA300 strain LAC induced localized lung damage in a rabbit model of pneumonia, characterized by bronchopneumonia observed histologically. Disease in the mutant-infected rabbits was restricted in distribution compared to that in wild-type USA300-infected rabbits. We also found that SplA is able to cleave the mucin 16 glycoprotein from the surface of the CalU-3 lung cell line, suggesting a possible mechanism for wild-type USA300 spreading pneumonia to both lungs. Investigation of the secreted and surface proteomes of wild-type USA300 and the mutant revealed multiple alterations in metabolic proteins and virulence factors. This study demonstrates that the Spls modulate physiology and virulence, identifies a human target of SplA, and suggests potential targets of the Spl proteases. is a versatile human pathogen that produces an array of virulence factors, including several proteases. Of these, six proteases called the Spls are the least characterized. Previous evidence suggests that the Spls are expressed during human infection; however, their function is unknown. Our study shows that the Spls are required for to cause disseminated lung damage during pneumonia. Further, we present the first example of a human protein cut by an Spl protease. Although the Spls were predicted not to cut staphylococcal proteins, we also show that an mutant has altered abundance of both secreted and surface-associated proteins. This work provides novel insight into the function of Spls during infection and their potential ability to degrade both staphylococcal and human proteins.
Spl蛋白酶是一组由六种丝氨酸蛋白酶组成的蛋白，它们由νSaβ致病岛编码，且具有独特性。尽管它们的生物化学性质很有趣，但其生物学底物和在毒力方面的功能一直难以阐明。我们发现，社区获得性耐甲氧西林金黄色葡萄球菌USA300菌株LAC的一个操纵子突变体在兔肺炎模型中诱导了局部肺损伤，组织学观察显示为支气管肺炎。与野生型USA300感染的兔子相比，突变体感染兔子的疾病分布受到限制。我们还发现SplA能够从CalU-3肺细胞系表面切割粘蛋白16糖蛋白，这提示了野生型USA300将肺炎传播至双肺的一种可能机制。对野生型USA300和该突变体的分泌蛋白组和表面蛋白组的研究揭示了代谢蛋白和毒力因子的多种变化。这项研究表明Spl蛋白调节生理和毒力，鉴定出了SplA的一个人类靶点，并提示了Spl蛋白酶的潜在靶点。金黄色葡萄球菌是一种多能的人类病原体，能产生一系列毒力因子，包括几种蛋白酶。其中，六种被称为Spl的蛋白酶的特征了解最少。先前的证据表明Spl在人类感染期间表达；然而，其功能尚不清楚。我们的研究表明，Spl是金黄色葡萄球菌在肺炎期间导致弥漫性肺损伤所必需的。此外，我们展示了第一个被Spl蛋白酶切割的人类蛋白的例子。尽管预测Spl不会切割葡萄球菌蛋白，但我们还表明，一个操纵子突变体改变了分泌蛋白和表面相关蛋白的丰度。这项工作为Spl在感染期间的功能及其降解葡萄球菌和人类蛋白的潜在能力提供了新的见解。
