Structural and functional analyses of the N-terminal domain of the A subunit of a Bacillus megaterium spore germinant receptor
Structural and functional analyses of the N-terminal domain of the A subunit of a Bacillus megaterium spore germinant receptor
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DOI：
10.1073/pnas.1903675116
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发表时间：
2019-06-04
影响因子：
11.1
通讯作者：
Hao, Bing
中科院分区：
文献类型：
--
作者：
Li, Yunfeng;Jin, Kai;Hao, Bing
芽孢杆菌孢子的萌发是由特定的营养分子与位于孢子内膜上的萌发受体（GR）相互作用诱导的。GR通常由称为A、B和C的三个亚基组成，尽管单个亚基的功能尚不清楚。在这里，我们提出了巨大芽孢杆菌GerK（3）GR的A亚基的N-末端结构域（NTD）的晶体结构，揭示了两个不同的球状亚结构域被一个裂缝一分为二，一个折叠与细菌ABC转运蛋白的底物结合蛋白具有很强的同源性。分子对接，化学位移扰动测量，诱变再加上孢子萌发分析支持一个拟议的模型，GRA亚基的NTD中的两个子域之间的接口作为萌发剂结合位点，并在孢子萌发中起着至关重要的作用。我们的研究结果提供了一个概念框架，了解发芽招聘机制，GR触发孢子萌发。
Germination of Bacillus spores is induced by the interaction of specific nutrient molecules with germinant receptors (GRs) localized in the spore's inner membrane. GRs typically consist of three subunits referred to as A, B, and C, although functions of individual subunits are not known. Here we present the crystal structure of the N-terminal domain (NTD) of the A subunit of the Bacillus megaterium GerK(3) GR, revealing two distinct globular subdomains bisected by a cleft, a fold with strong homology to substrate-binding proteins in bacterial ABC transporters. Molecular docking, chemical shift perturbation measurement, and mutagenesis coupled with spore germination analyses support a proposed model that the interface between the two subdomains in the NTD of GR A subunits serves as the germinant binding site and plays a critical role in spore germination. Our findings provide a conceptual framework for understanding the germinant recruitment mechanism by which GRs trigger spore germination.