机会致病菌肺炎链球菌(肺炎球菌)是人类鼻咽共生菌,和宿主N-聚糖代谢促进其定殖和侵袭。据报道,葡萄糖抑制,而Fetuin,一种糖基化模型蛋白,诱导,通过双组分系统TCS07参与N-聚糖降解的基因。然而,葡萄糖抑制和TCS07诱导的机制尚不清楚.以前,我们发现肺炎球菌水甘油Pn-AqpC促进氧气吸收,从而有助于抗氧化潜力和毒力。在这项研究中,通过串联质量标签(TMT)定量蛋白质组学,我们发现,Pn-aqpC缺失导致葡萄糖培养的肺炎球菌R6中11种参与N-聚糖降解的蛋白质显著上调.定量RT-PCR和GFP荧光报告基因显示,N-聚糖基因的上调完全依赖于反应调节因子(RR)07,但不依赖于TCS07的组氨酸激酶HK07或ΔPn-aqpC中RR07的磷酸化天冬氨酸残基,表明当Pn-AqpC缺失时,RR07以HK07独立方式激活。Pn-aqpC的缺失还增强了丙酮酸甲酸裂解酶的表达并增加了甲酸产量,可能是由于细胞氧含量降低,表明葡萄糖分解代谢向混合酸发酵的分流发生。值得注意的是,甲酸盐诱导了葡萄糖生长的R6中的N-聚糖降解基因,但rr07的缺失消除了这种诱导,表明甲酸盐激活RR07。然而,N-聚糖降解蛋白的诱导降低了R6在葡萄糖中的种内竞争。因此,虽然N-聚糖降解促进肺炎球菌的发病机制,本文报道的基于葡萄糖代谢物的RR07调控对于平衡肺炎球菌的生长适应性和致病性具有重要意义.重要性肺炎球菌,一种人类机会病原体,能够代谢宿主复合物N-聚糖。N-聚糖降解促进肺炎球菌在鼻咽中的定植以及侵入更深的组织,从而显着促进发病机制。已知双组分系统07诱导N-聚糖代谢基因;然而,TCS07是如何激活的仍然未知。这项研究表明,甲酸,肺炎球菌的厌氧发酵代谢产物,是响应调节剂(RR)07的新型激活剂。尽管N-聚糖降解基因的高表达促进了肺炎球菌在鼻咽中的定植和发病机理,如这项工作所示,这会降低葡萄糖中肺炎球菌的生长适应性。值得注意的是,Pn-AqpC的存在,一种输氧的水甘油,使肺炎球菌维持葡萄糖高乳酸发酵,从而减少了甲酸盐的产生,保持RR07失活,并将N-聚糖降解基因控制在非诱导状态。因此,这项研究强调了一种新的发酵代谢模式,该模式将TCS调节的碳水化合物利用策略作为肺炎球菌适应性和致病性之间的权衡。
The opportunistic pathogen Streptococcus pneumoniae (pneumococcus) is a human nasopharyngeal commensal, and host N-glycan metabolism promotes its colonization and invasion. It has been reported that glucose represses, while fetuin, a glycoconjugated model protein, induces, the genes involved in N-glycan degradation through the two-component system TCS07. However, the mechanisms of glucose repression and TCS07 induction remain unknown. Previously, we found that the pneumococcal aquaglyceroporin Pn-AqpC facilitates oxygen uptake, thereby contributing to the antioxidant potential and virulence. In this study, through Tandem Mass Tag (TMT) quantitative proteomics, we found that the deletion of Pn-aqpC caused a marked upregulation of 11 proteins involved in N-glycan degradation in glucose-grown pneumococcus R6. Both quantitative RT-PCR and GFP fluorescence reporters revealed that the upregulation of N-glycan genes was completely dependent on response regulator (RR) 07, but not on the histidine kinase HK07 of TCS07 or the phosphoryl-receiving aspartate residue of RR07 in ΔPn-aqpC, indicating that RR07 was activated in an HK07-independent manner when Pn-AqpC was absent. The deletion of Pn-aqpC also enhanced the expression of pyruvate formate lyase and increased formate production, probably due to reduced cellular oxygen content, indicating that a shunt of glucose catabolism to mixed acid fermentation occurs. Notably, formate induced the N-glycan degradation genes in glucose-grown R6, but the deletion of rr07 abolished this induction, indicating that formate activates RR07. However, the induction of N-glycan degradation proteins reduced the intraspecies competition of R6 in glucose. Therefore, although N-glycan degradation promotes pneumococcal pathogenesis, the glucose metabolites-based RR07 regulation reported here is of importance for balancing growth fitness and the pathogenicity of pneumococcus. IMPORTANCE Pneumococcus, a human opportunistic pathogen, is capable of metabolizing host complex N-glycans. N-glycan degradation promotes pneumococcus colonization in the nasopharynx as well as invasion into deeper tissues, thus significantly contributing to pathogenesis. It is known that the two-component system 07 induces the N-glycan metabolizing genes; however, how TCS07 is activated remains unknown. This study reveals that formate, the anaerobic fermentation metabolite of pneumococcus, is a novel activator of the response regulator (RR) 07. Although the high expression of N-glycan degradation genes promotes pneumococcal colonization in the nasopharynx and pathogenesis, this reduces pneumococcal growth fitness in glucose as indicated in this work. Notably, the presence of Pn-AqpC, an oxygen-transporting aquaglyceroporin, enables pneumococcus to maintain glucose homolactic acid fermentation, thus reducing formate production, maintaining RR07 inactivation, and controlling N-glycan degrading genes at a non-induced status. Thus, this study highlights a novel fermentation metabolism pattern linking TCS-regulated carbohydrate utilization strategies as a trade-off between the fitness and the pathogenicity of pneumococcus.