Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA.
Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
J Bacteriol. 2017 Dec 5;200(1). doi: 10.1128/JB.00389-17. Print 2018 Jan 1.
A hallmark of bacterial biofilms is the production of an xtraellular atrix (ECM) that encases and protects the community from environmental stressors. Biofilm formation is an integral portion of the roathogenic (UPEC) life cycle. Approximately 2% of UPEC isolates are cysteine auxotrophs. Here, we investigated how cysteine homeostasis impacted UPEC UTI89 strain biofilm formation and, specifically, the production of the ECM components curli and cellulose. Cysteine auxotrophs produced less cellulose and slightly more curli compared to wild-type (WT) strains, and cysteine auxotrophs formed smooth, nonrugose colonies. Cellulose production was restored in cysteine auxotrophs when YfiR was inactivated. YfiR is a redox-sensitive regulator of the diguanylate cyclase, YfiN. The production of curli, a temperature-regulated appendage, was independent of temperature in UTI89 cysteine auxotrophs. In a screen of UPEC isolates, we found that ∼60% of UPEC cysteine auxotrophs produced curli at 37°C, but only ∼2% of cysteine prototrophic UPEC isolates produced curli at 37°C. Interestingly, sublethal concentrations of amdinocillin and trimethoprim-sulfamethoxazole inhibited curli production, whereas strains auxotrophic for cysteine continued to produce curli even in the presence of amdinocillin and trimethoprim-sulfamethoxazole. The dysregulation of ECM components and resistance to amdinocillin in cysteine auxotrophs may be linked to hyperoxidation, since the addition of exogenous cysteine or glutathione restored WT biofilm phenotypes to mutants unable to produce cysteine and glutathione. Uropathogenic (UPEC) bacteria are the predominant causative agent of urinary tract infections (UTIs). UTIs account for billions of dollars of financial burden annually to the health care industry in the United States. Biofilms are an important aspect of the UPEC pathogenesis cascade and for the establishment of chronic infections. Approximately 2% of UPEC isolates from UTIs are cysteine auxotrophs, yet there is relatively little known about the biofilm formation of UPEC cysteine auxotrophs. Here we show that cysteine auxotrophs have dysregulated biofilm components due to a change in the redox state of the periplasm. Additionally, we show the relationship between cysteine auxotrophs, biofilms, and antibiotics frequently used to treat UTIs.
细菌生物膜的一个标志是产生细胞外基质 (ECM)，它将群落包裹并保护起来，使其免受环境胁迫。生物膜的形成是尿路致病性大肠杆菌 (UPEC) 生命周期的一个组成部分。大约 2%的 UPEC 分离株是半胱氨酸营养缺陷型。在这里，我们研究了半胱氨酸动态平衡如何影响 UPEC UTI89 菌株生物膜的形成，特别是细胞外基质成分卷曲和纤维素的产生。与野生型 (WT) 菌株相比，半胱氨酸营养缺陷型产生的纤维素较少，卷曲更多，并且形成光滑、非粗糙的菌落。当失活 YfiR 时，半胱氨酸营养缺陷型中纤维素的产生得以恢复。YfiR 是双鸟苷酸环化酶 YfiN 的氧化还原敏感调节剂。在 UTI89 半胱氨酸营养缺陷型中，温度调节附属物卷曲的产生不依赖于温度。在 UPEC 分离株的筛选中，我们发现约 60%的 UPEC 半胱氨酸营养缺陷型在 37°C 时产生卷曲，但只有约 2%的半胱氨酸原养型 UPEC 分离株在 37°C 时产生卷曲。有趣的是，亚致死浓度的氨丁西林和甲氧苄啶抑制卷曲的产生，而半胱氨酸营养缺陷型菌株即使在存在氨丁西林和甲氧苄啶的情况下也继续产生卷曲。细胞外基质成分的失调和对半氨西林的耐药性与超氧化有关，因为外源性半胱氨酸或谷胱甘肽的添加恢复了不能产生半胱氨酸和谷胱甘肽的突变体的 WT 生物膜表型。尿路致病性大肠杆菌 (UPEC) 是尿路感染 (UTI) 的主要病原体。UTI 每年给美国医疗保健行业带来数十亿美元的经济负担。生物膜是 UPEC 发病机制级联和慢性感染建立的一个重要方面。大约 2%的 UTI 中 UPEC 分离株是半胱氨酸营养缺陷型，但人们对 UPEC 半胱氨酸营养缺陷型生物膜的形成知之甚少。在这里，我们发现由于周质氧化还原状态的改变，半胱氨酸营养缺陷型生物膜的组成部分失调。此外，我们还展示了半胱氨酸营养缺陷型、生物膜和抗生素之间的关系，抗生素是治疗 UTI 常用的药物。
