Expression and function of secreted proteases in commensal lifestyles of Staphylococci

葡萄球菌共生生活方式中分泌蛋白酶的表达和功能

• 批准号: 386645-2011
• 负责人: McGavin, Martin
• 金额: $ 2.62万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=550532
• 关键词: Expression; function; secreted; proteases; commensal

Proteases are proteins that degrade or process other proteins, and contribute to important or essential functions in all forms of life. Proteases also contribute to the ability of bacteria to cause disease. Some bacteria are part of the human microflora, where they discourage the growth of disease causing bacteria. Our research will evaluate how differences in function and expression of a similar secreted protease contribute to the ability of two related species of Staphylococci to colonize the nose of humans. Of these, Staphylococcus aureus only colonizes the nose, but can also cause severe infections if it breaches the epithelial barrier. In contrast, S. epidermidis is also ubiquitous on human skin, but rarely causes severe infections. Importantly, a secreted protease of S. epidermidis, named Esp interferes with the ability of S. aureus to colonize the nose. Surprisingly, S. aureus is capable of producing a very similar protease. We propose that growth conditions in the nose signal S. epidermidis to produce this protease, to discourage growth of S. aureus, while the same environmental conditions instruct S. aureus not to produce the protease. We believe that S. aureus only produces this protease once it enters the body and causes an infection, where it does not have to compete with S. epidermidis. Consequently, determining the signals that instruct these bacteria to either produce, or not produce this protease, will lead to a better understanding of how some bacteria are instructed to cause disease, and others respond to the same instructions to maintain human health. We will test the ability of each microbe to produce protease in response to signals that may be encountered in the nose or on the skin, including changes in acidity, presence of free fatty acids, and the availability of oligopeptides. Sensor proteins that help the bacteria respond to these signals will be identified, and we will inactivate these proteins to determine how the bacteria respond to their loss. Finally, we will isolate the protease from each bacteria, and modify its properties so that we can understand how it functions to either promote commensalism of S. epidermidis, or alternately to discourage colonization of S. aureus.

蛋白酶是降解或加工其他蛋白质的蛋白质，并有助于所有形式的生命中的重要或基本功能。蛋白酶也有助于细菌引起疾病的能力。有些细菌是人体微生物区系的一部分，它们阻止致病细菌的生长。我们的研究将评估相似的分泌蛋白酶的功能和表达差异如何有助于两种相关葡萄球菌在人类鼻子中定植的能力。 其中，金黄色葡萄球菌只在鼻子上定植，但如果它破坏了上皮屏障，也会引起严重的感染。相反，S.表皮病也普遍存在于人类皮肤上，但很少引起严重感染。重要的是，S. epidermidis，命名为Esp，它干扰S.金黄色葡萄球菌定植于鼻内。令人惊讶的是，S。金黄色葡萄球菌能够产生非常相似的蛋白酶。我们建议在鼻信号S中的生长条件。epidermidis产生这种蛋白酶，抑制S. aureus，而相同的环境条件指示S.金黄色葡萄球菌不产生蛋白酶。我们认为S.金黄色葡萄球菌只有在进入人体并引起感染时才产生这种蛋白酶，而不必与金黄色葡萄球菌竞争。表皮的因此，确定指示这些细菌产生或不产生这种蛋白酶的信号，将有助于更好地了解一些细菌是如何被指示引起疾病的，而其他细菌则对相同的指示做出反应以维持人类健康。我们将测试每种微生物产生蛋白酶的能力，以响应可能在鼻子或皮肤上遇到的信号，包括酸度的变化，游离脂肪酸的存在和寡肽的可用性。帮助细菌对这些信号做出反应的传感器蛋白将被识别出来，我们将对这些蛋白进行测序，以确定细菌对它们的损失有何反应。最后，我们将从每种细菌中分离蛋白酶，并修改其性质，以便我们能够了解它是如何发挥作用的，无论是促进S。epidermidis，或者阻止S.金黄色。