In Staphylococcus aureus, virulence is under the control of a quorum sensing (QS) circuit encoded in the accessory gene regulator ( agr ) genomic locus. Key to this pathogenic behavior is the production and signaling activity of a secreted pheromone, the autoinducing peptide (AIP), generated following the ribosomal synthesis and posttranslational modification of a precursor polypeptide, AgrD, through two discrete cleavage steps. The integral membrane protease AgrB is known to catalyze the first processing event, generating the AIP biosynthetic intermediate, AgrD (1–32) thiolactone. However, the identity of the second protease in this biosynthetic pathway, which removes an N-terminal leader sequence, has remained ambiguous. Here, we show that membrane protease regulator of agr QS (MroQ), an integral membrane protease recently implicated in the agr response, is directly involved in AIP production. Genetic complementation and biochemical experiments reveal that MroQ proteolytic activity is required for AIP biosynthesis in agr specificity group I and group II, but not group III. Notably, as part of this effort, the biosynthesis and AIP-sensing arms of the QS circuit were reconstituted together in vitro. Our experiments also reveal the molecular features guiding MroQ cleavage activity, a critical factor in defining agr specificity group identity. Collectively, our study adds to the molecular understanding of the agr response and Staphylococcus aureus virulence.

中文翻译：

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金黄色葡萄球菌 agr 群体感应通路的重建揭示了整合膜蛋白酶 MroQ 在信息素生物合成中的直接作用

在金黄色葡萄球菌，毒力受编码在辅助基因调节器中的群体感应（QS）电路的控制（农业) 基因组位点。这种致病行为的关键是分泌的信息素、自诱导肽 (AIP) 的产生和信号活动，它是在核糖体合成和前体多肽 AgrD 的翻译后修饰后通过两个不连续的切割步骤产生的。已知整合膜蛋白酶 AgrB 催化第一个加工事件，产生 AIP 生物合成中间体 AgrD (1–32) 硫内酯。然而，该生物合成途径中第二个蛋白酶的身份（去除 N 末端前导序列）仍然不明确。在这里，我们展示了膜蛋白酶调节剂农业QS (MroQ)，一种整合膜蛋白酶，最近与农业响应，直接参与 AIP 生产。遗传互补和生化实验表明，MroQ 蛋白水解活性是 AIP 生物合成所必需的农业特异性 I 组和 II 组，但不包括 III 组。值得注意的是，作为这项工作的一部分，QS 电路的生物合成和 AIP 传感臂在体外重组在一起。我们的实验还揭示了指导 MroQ 切割活性的分子特征，这是定义的关键因素农业特异性群体身份。总的来说，我们的研究增加了对分子的理解农业响应和金黄色葡萄球菌毒力。