Data_Sheet_1_Peptidoglycan Endopeptidase Spr of Uropathogenic Escherichia coli Contributes to Kidney Infections and Competitive Fitness During Bladder Colonization.pdf

Uropathogenic Escherichia coli (UPEC) is the most common pathogen of urinary tract infections (UTIs). Antibiotic therapy is the conventional measure to manage such infections. However, the rapid emergence of antibiotic resistance has reduced the efficacy of antibiotic treatment. Given that the bacterial factors required for the full virulence of the pathogens are potential therapeutic targets, identifying such factors may facilitate the development of novel therapeutic strategies against UPEC UTIs. The peptidoglycan (PG) endopeptidase Spr (also named MepS) is required for PG biogenesis in E. coli. In the present study, we found that Spr deficiency attenuated the ability of UPEC to infect kidneys and induced a fitness defect during bladder colonization in a mouse model of UTI. Based on the liquid chromatography (LC)/mass spectrometry (MS)/MS analysis of the bacterial envelope, spr deletion changed the levels of some envelope-associated proteins, suggesting that Spr deficiency interfere with the components of the bacterial structure. Among the proteins, FliC was significantly downregulated in the spr mutant, which is resulted in reduced motility. Lack of Spr might hinder the function of the flagellar transcriptional factor FlhDC to decrease FliC expression. The motility downregulation contributed to the reduced fitness in urinary tract colonization. Additionally, spr deletion compromised the ability of UPEC to evade complement-mediated attack and to resist intracellular killing of phagocytes, consequently decreasing UPEC bloodstream survival. Spr deficiency also interfered with the UPEC morphological switch from bacillary to filamentous shapes during UTI. It is known that bacterial filamentation protects UPEC from phagocytosis by phagocytes. In conclusion, Spr deficiency was shown to compromise multiple virulence properties of UPEC, leading to attenuation of the pathogen in urinary tract colonization and bloodstream survival. These findings indicate that Spr is a potential antimicrobial target for further studies attempting to develop novel strategies in managing UPEC UTIs.

尿路感染（UTIs）最常见的病原体为尿路致病性大肠杆菌（UPEC）。抗生素治疗是此类感染的传统管理措施。然而，抗生素耐药性的迅速出现已降低了抗生素治疗的有效性。鉴于病原体完全致病所需的细菌因子是潜在的治疗靶点，识别这些因子可能有助于开发针对UPEC UTIs的新型治疗策略。肽聚糖（PG）内肽酶Spr（亦称MepS）对于大肠杆菌中的PG生物合成是必需的。在本研究中，我们发现Spr缺陷削弱了UPEC感染肾脏的能力，并在UTI小鼠模型中膀胱定植期间诱导了适应性缺陷。基于细菌包膜的液相色谱（LC）/质谱（MS）/MS分析，spr缺失改变了某些包膜相关蛋白的水平，这表明Spr缺陷干扰了细菌结构的组成成分。在这些蛋白中，FliC在spr突变体中显著下调，导致运动能力降低。Spr缺乏可能阻碍了鞭毛转录因子FlhDC的功能，从而降低FliC的表达。运动能力的下调有助于在尿路定植中的适应性降低。此外，spr缺失损害了UPEC逃避补体介导的攻击和抵抗吞噬细胞细胞内杀灭的能力，从而降低了UPEC在血液循环中的存活率。Spr缺陷还干扰了UPEC在UTI期间从杆状到丝状形态的转变。众所周知，细菌丝状化可以保护UPEC免受吞噬细胞的吞噬。总之，Spr缺陷已被证明损害了UPEC的多种致病特性，导致病原体在尿路定植和血液循环中的存活能力减弱。这些发现表明，Spr是进一步研究、旨在开发管理UPEC UTIs新策略的潜在抗菌靶点。