Department of Clinical Pathology, Cheng Hsin General Hospital, Taipei, Taiwan.
Department of Restaurant, Hotel and Institutional Management, Fu-Jen Catholic University, New Taipei City, Taiwan.
BMC Microbiol. 2020 Oct 14;20(1):312. doi: 10.1186/s12866-020-01989-z.
Stenotrophomonas maltophilia, an opportunistic pathogen, is ubiquitously present in various environments, signifying its high capability of environmental adaptation. Two-component regulatory system (TCS) is a powerful implement to help organisms to survive in different environments. In clinic, treatment of S. maltophilia infection is difficult because it is naturally resistant to many antibiotics, highlighting the necessity to develop novel drugs or adjuvants. Given their critical and extensively regulatory role, TCS system has been proposed as a convincing target for novel drugs or adjuvants. PhoPQ TCS, a highly conserved TCS in several pathogens, plays crucial roles in low-magnesium adaption, polymyxin resistance, and virulence. In this study, we aimed to characterize the role of PhoPQ TCS of S. maltophilia in antibiotic susceptibility, physiology, stress adaptation, and virulence.
To characterize PhoPQ system, phoP single mutant as well as phoP and phoQ double mutant were constructed. Distinct from most phoPQ systems of other microorganisms, two features were observed during the construction of phoP and phoQ single deletion mutant. Firstly, the phoQ mutant was not successfully obtained. Secondly, the compromised phenotypes of phoP mutant were not reverted by complementing an intact phoP gene, but were partially restored by complementing a phoPQ operon. Thus, wild-type KJ, phoP mutant (KJΔPhoP), phoPQ mutant (KJΔPhoPQ), and complemented strain (KJΔPhoPQ (pPhoPQ)) were used for functional assays, including antibiotic susceptibility, physiology (swimming motility and secreted protease activity), stress adaptation (oxidative, envelope, and iron-depletion stresses), and virulence to Caenorhabditis elegans. KJΔPhoPQ totally lost swimming motility, had enhanced secreted protease activity, increased susceptibility to antibiotics (β-lactam, quinolone, aminoglycoside, macrolide, chloramphenicol, and sulfamethoxazole/ trimethoprim), menadione, HO, SDS, and 2,2'-dipyridyl, as well as attenuated virulence to C. elegans. Trans-complementation of KJΔPhoPQ with phoPQ reverted these altered phenotypes to the wild-type levels.
Given the critical and global roles of PhoPQ TCS in antibiotic susceptibility, physiology, stress adaptation, and virulence, PhoPQ is a potential target for the design of drugs or adjuvants.
嗜麦芽窄食单胞菌是一种机会致病菌，广泛存在于各种环境中，表明其具有很强的环境适应能力。双组分调控系统（TCS）是一种帮助生物体在不同环境中生存的强大工具。在临床上，嗜麦芽窄食单胞菌感染的治疗很困难，因为它天然对抗生素具有多种耐药性，这凸显了开发新型药物或佐剂的必要性。鉴于 TCS 系统在调控中的关键作用及其广泛的作用，它已被提议作为新型药物或佐剂的有吸引力的靶标。PhoPQ TCS 是几种病原体中高度保守的 TCS，在低镁适应、多粘菌素耐药性和毒力中发挥关键作用。在这项研究中，我们旨在研究嗜麦芽窄食单胞菌 PhoPQ TCS 在抗生素敏感性、生理、应激适应和毒力中的作用。
为了研究 PhoPQ 系统，构建了 phoP 单突变体和 phoP 和 phoQ 双突变体。与其他微生物的大多数 phoPQ 系统不同，在构建 phoP 和 phoQ 单缺失突变体时观察到两个特征。首先，无法成功获得 phoQ 突变体。其次，phoP 突变体的表型缺陷不能通过互补完整的 phoP 基因来恢复，但通过互补 phoPQ 操纵子部分恢复。因此，使用野生型 KJ、phoP 突变体（KJΔPhoP）、phoPQ 突变体（KJΔPhoPQ）和互补菌株（KJΔPhoPQ（pPhoPQ））进行功能测定，包括抗生素敏感性、生理（泳动和分泌蛋白酶活性）、应激适应（氧化、包膜和铁耗竭应激）和对秀丽隐杆线虫的毒力。KJΔPhoPQ 完全丧失泳动能力，分泌蛋白酶活性增强，对β-内酰胺类、喹诺酮类、氨基糖苷类、大环内酯类、氯霉素和磺胺甲噁唑/甲氧苄啶、甲萘醌、HO、SDS 和 2,2'-联吡啶的敏感性增加，对秀丽隐杆线虫的毒力减弱。用 phoPQ 对 KJΔPhoPQ 的反式互补恢复了这些表型改变至野生型水平。
鉴于 PhoPQ TCS 在抗生素敏感性、生理、应激适应和毒力方面的关键和全局作用，PhoPQ 是设计药物或佐剂的潜在靶标。
