Department of Biological Sciences, Ohio University, Athens, OH 45701, USA.
The Infectious and Tropical Disease Institute, Ohio University, Athens, OH 45701, USA.
Toxins (Basel). 2019 Jun 16;11(6):343. doi: 10.3390/toxins11060343.
Peptidyl-prolyl isomerases (PPIases) are enzymes that catalyze the -to- isomerization around proline bonds, allowing proteins to fold into their correct confirmation. Previously, we identified two PPIase enzymes in (PpiB and PrsA) that are involved in the regulation of virulence determinants and have shown that PpiB contributes to virulence in a murine abscess model of infection. Here, we further examine the role of these PPIases in virulence and, in particular, their regulation of hemolytic toxins. Using murine abscess and systemic models of infection, we show that a mutant in a USA300 background is attenuated for virulence but that a mutant is not. Deletion of the gene leads to decreased bacterial survival in macrophages and nasal epithelial cells, while there is no significant difference when is deleted. Analysis of culture supernatants reveals that a mutant strain has reduced levels of the phenol-soluble modulins and that both and mutants have reduced alpha-toxin activity. Finally, we perform immunoprecipitation to identify cellular targets of PpiB and PrsA. Results suggest a novel role for PpiB in protein secretion. Collectively, our results demonstrate that PpiB and PrsA influence toxins via distinct mechanisms, and that PpiB but not PrsA contributes to disease.
肽基脯氨酰顺反异构酶（PPIases）是一类能够催化脯氨酸键形成顺反异构的酶，使蛋白质能够折叠成正确的构象。此前，我们在 （PpiB 和 PrsA）中鉴定了两种参与毒力决定因子调控的 PPIase 酶，并且已经表明 PpiB 有助于感染小鼠脓肿模型中的 毒力。在这里，我们进一步研究了这些 PPIases 在 毒力中的作用，特别是它们对溶血毒素的调控作用。使用小鼠脓肿和全身感染模型，我们表明在 USA300 背景下的 突变体在毒力方面减弱，但 突变体不是。 基因的缺失导致巨噬细胞和鼻上皮细胞中细菌的存活率降低，而当 缺失时没有显著差异。对培养上清液的分析表明，一株 突变株的酚可溶性调节素水平降低，并且 和 突变株的α-毒素活性降低。最后，我们进行免疫沉淀以鉴定 PpiB 和 PrsA 的细胞靶标。结果表明 PpiB 在 蛋白分泌中具有新的作用。总之，我们的结果表明 PpiB 和 PrsA 通过不同的机制影响 毒素，并且 PpiB 而不是 PrsA 导致疾病。
