An Aspartate-Specific Solute-Binding Protein Regulates Protein Kinase G Activity To Control Glutamate Metabolism in Mycobacteria.
An Aspartate-Specific Solute-Binding Protein Regulates Protein Kinase G Activity To Control Glutamate Metabolism in Mycobacteria.
复制标题
天冬氨酸特异性溶质结合蛋白调节蛋白激酶G活性以控制分枝杆菌中的谷氨酸代谢。
DOI：
10.1128/mbio.00931-18
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发表时间：
2018-07-31
期刊：
影响因子：
6.4
通讯作者：
O'Hare HM
中科院分区：
文献类型：
--
作者：
Bhattacharyya N;Nkumama IN;Newland-Smith Z;Lin LY;Yin W;Cullen RE;Griffiths JS;Jarvis AR;Price MJ;Chong PY;Wallis R;O'Hare HM
通过丝氨酸/苏氨酸磷酸化的信号传导控制细菌中的多种过程，并且识别激活蛋白激酶的刺激物是该领域中的突出问题。最近，我们发现营养素刺激耻垢分枝杆菌和结核分枝杆菌中蛋白激酶G底物GarA的磷酸化，并且GarA在调节中枢代谢中的作用取决于它是否磷酸化。在这里，我们提出了一个调查营养素激活PknG的机制。两个未知基因被鉴定为与PknG共保守和共表达：它们的产物是推定的脂蛋白GlnH和推定的跨膜蛋白GlnX。使用遗传方法，我们表明膜蛋白GlnX与PknG功能相关。此外，我们确定GlnH的配体特异性与刺激GarA磷酸化的氨基酸相匹配。我们确定了GlnH与不同氨基酸配体（天冬氨酸、谷氨酸和天冬酰胺）复合的结构，揭示了配体特异性的结构基础。我们建议，在周质中的氨基酸浓度是由GlnH和蛋白质-蛋白质相互作用，允许跨膜通过GlnX激活PknG的信息传输。这种感觉系统将允许响应于营养物质可用性的变化来调节营养物质的利用。传感器、信号传导和效应蛋白在整个放线菌中是保守的，包括重要的人类病原体结核分枝杆菌、工业氨基酸生产者谷氨酸棒杆菌和产肉毒杆菌的链霉菌。结核病每天造成5 000人死亡，耐多药结核病的流行率在每个国家都在上升。病原体结核分枝杆菌感知和响应其环境变化的过程是药物开发的有吸引力的目标。细菌代谢在生长和休眠细胞之间有很大的不同，这些变化在结核病的发病机制中很重要。在这里，我们使用遗传和生物化学方法来鉴定允许结核分枝杆菌检测其周围环境中的氨基酸的蛋白质，以便它可以调节其代谢。我们还展示了单个氨基酸是如何被识别的。这些发现对其他放线菌病原体具有更广泛的意义，例如非结核分枝杆菌，以及每年用于生产数十亿美元氨基酸和抗生素的放线菌。
Signaling by serine/threonine phosphorylation controls diverse processes in bacteria, and identification of the stimuli that activate protein kinases is an outstanding question in the field. Recently, we showed that nutrients stimulate phosphorylation of the protein kinase G substrate GarA in Mycobacterium smegmatis and Mycobacterium tuberculosis and that the action of GarA in regulating central metabolism depends upon whether it is phosphorylated. Here we present an investigation into the mechanism by which nutrients activate PknG. Two unknown genes were identified as co-conserved and co-expressed with PknG: their products were a putative lipoprotein, GlnH, and putative transmembrane protein, GlnX. Using a genetic approach, we showed that the membrane protein GlnX is functionally linked to PknG. Furthermore, we determined that the ligand specificity of GlnH matches the amino acids that stimulate GarA phosphorylation. We determined the structure of GlnH in complex with different amino acid ligands (aspartate, glutamate, and asparagine), revealing the structural basis of ligand specificity. We propose that the amino acid concentration in the periplasm is sensed by GlnH and that protein-protein interaction allows transmission of this information across the membrane via GlnX to activate PknG. This sensory system would allow regulation of nutrient utilization in response to changes in nutrient availability. The sensor, signaling, and effector proteins are conserved throughout the Actinobacteria, including the important human pathogen Mycobacterium tuberculosis, industrial amino acid producer Corynebacterium glutamicum, and antibiotic-producing Streptomyces species. Tuberculosis (TB) kills 5,000 people every day, and the prevalence of multidrug-resistant TB is increasing in every country. The processes by which the pathogen Mycobacterium tuberculosis senses and responds to changes in its environment are attractive targets for drug development. Bacterial metabolism differs dramatically between growing and dormant cells, and these changes are known to be important in pathogenesis of TB. Here, we used genetic and biochemical approaches to identify proteins that allow M. tuberculosis to detect amino acids in its surroundings so that it can regulate its metabolism. We have also shown how individual amino acids are recognized. The findings have broader significance for other actinobacterial pathogens, such as nontuberculous mycobacteria, as well as Actinobacteria used to produce billions of dollars of amino acids and antibiotics every year.