University of Lille, Lille, France.
CNRS UMR 8204, Lille, France.
mBio. 2018 Feb 27;9(1):e02052-17. doi: 10.1128/mBio.02052-17.
controls the expression of its virulence regulon through the two-component system BvgAS. BvgS is a prototype for a family of multidomain sensor kinases. In BvgS, helical linkers connect periplasmic Venus flytrap (VFT) perception domains to a cytoplasmic Per-Arnt-Sim (PAS) domain and the PAS domain to the dimerization/histidine phosphotransfer (DHp) domain of the kinase. The two linkers can adopt coiled-coil structures but cannot do so simultaneously. The first linker forms a coiled coil in the kinase mode and the second in the phosphatase mode, with the other linker in both cases showing an increase in dynamic behavior. The intervening PAS domain changes its quaternary structure between the two modes. In BvgS homologues without a PAS domain, a helical "X" linker directly connects the VFT and DHp domains. Here, we used BvgS as a platform to characterize regulation in members of the PAS-less subfamily. BvgS chimeras of homologues with natural X linkers displayed various regulation phenotypes. We identified two distinct coiled-coil registers in the N- and C-terminal portions of the X linkers. Stable coil formation in the C-terminal moiety determines the phosphatase mode, similarly to BvgS; in contrast, coil formation in the N-terminal moiety along the other register leads to the kinase mode. Thus, antagonism between two registers in the VFT-DHp linker forms the basis for activity regulation in the absence of the PAS domain. The N and C moieties of the X linker play roles similar to those played by the two independent linkers in sensor kinases with a PAS domain, providing a unified mechanism of regulation for the entire family. The whooping cough agent uses the BvgAS sensory transduction two-component system to regulate production of its virulence factors. BvgS serves as a model for a large family of multidomain bacterial sensor kinases. is virulent when BvgS functions as a kinase and avirulent when it switches to phosphatase activity in response to modulating signals. Understanding the molecular regulation of those proteins might lead to new antibacterial strategies. Here, we show that the linker regions between the perception and the enzymatic domains shift between distinct states of conformation in an alternating manner in response to signals and that their antagonistic changes control sensor kinase activity. These linker regions and mechanistic principles appear to be conserved among BvgS homologues, irrespective of the presence or absence of an intervening domain between the perception and the enzymatic domains. This work has thus uncovered general molecular mechanisms that regulate activity of sensor kinases in the BvgS family.
该系统通过双组分系统 BvgAS 来控制其毒力调节子的表达。BvgS 是多结构域传感器激酶家族的原型。在 BvgS 中，螺旋接头将周质 Venus flytrap (VFT) 感应结构域连接到细胞质 Per-Arnt-Sim (PAS) 结构域，将 PAS 结构域连接到激酶的二聚化/组氨酸磷酸转移 (DHp) 结构域。这两个接头可以采用卷曲螺旋结构，但不能同时采用。第一个接头在激酶模式下形成卷曲螺旋，第二个接头在磷酸酶模式下形成卷曲螺旋，而另一个接头在两种情况下都表现出动态行为的增加。 intervening PAS 结构域在两种模式之间改变其四元结构。在没有 PAS 结构域的 BvgS 同源物中，一个螺旋“X”接头直接将 VFT 和 DHp 结构域连接起来。在这里，我们使用 BvgS 作为平台来表征 PAS 缺失亚家族成员的调节。具有天然 X 接头的同源物的 BvgS 嵌合体显示出各种调节表型。我们在 X 接头的 N 和 C 末端部分鉴定了两个不同的卷曲螺旋登记处。C 末端部分稳定的螺旋形成决定了磷酸酶模式，类似于 BvgS；相比之下，N 末端部分沿着另一个登记处形成螺旋则导致激酶模式。因此，VFT-DHp 接头中两个登记处之间的拮抗作用构成了 PAS 结构域缺失时活性调节的基础。X 接头的 N 和 C 部分发挥的作用类似于具有 PAS 结构域的传感器激酶中两个独立接头的作用，为整个家族提供了统一的调节机制。百日咳剂利用 BvgAS 感觉转导双组分系统来调节其毒力因子的产生。BvgS 是一大类多结构域细菌传感器激酶的模型。当 BvgS 作为激酶发挥作用时，它是有毒的，而当它响应调节信号切换到磷酸酶活性时，它是无毒的。了解这些蛋白质的分子调节可能会导致新的抗菌策略。在这里，我们表明，在感知和酶结构域之间的接头区域在响应信号时以交替的方式在不同的构象状态之间移动，它们的拮抗变化控制传感器激酶的活性。这些接头区域和机械原理似乎在 BvgS 同源物中是保守的，无论感知和酶结构域之间是否存在中间结构域。这项工作因此揭示了调节 BvgS 家族中传感器激酶活性的一般分子机制。
