Vuong Cuong, Kocianova Stanislava, Voyich Jovanka M, Yao Yufeng, Fischer Elizabeth R, DeLeo Frank R, Otto Michael
Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories, NIAID, National Institutes of Health, Hamilton, Montana 59840, USA.
J Biol Chem. 2004 Dec 24;279(52):54881-6. doi: 10.1074/jbc.M411374200. Epub 2004 Oct 22.
Biofilms play an important role in many chronic bacterial infections. Production of an extracellular mixture of sugar polymers called exopolysaccharide is characteristic and critical for biofilm formation. However, there is limited information about the mechanisms involved in the biosynthesis and modification of exopolysaccharide components and how these processes influence bacterial pathogenesis. Staphylococcus epidermidis is an important human pathogen that frequently causes persistent infections by biofilm formation on indwelling medical devices. It produces a poly-N-acetylglucosamine molecule that emerges as an exopolysaccharide component of many bacterial pathogens. Using a novel method based on size exclusion chromatography-mass spectrometry, we demonstrate that the surface-attached protein IcaB is responsible for deacetylation of the poly-N-acetylglucosamine molecule. Most likely due to the loss of its cationic character, non-deacetylated poly-acetylglucosamine in an isogenic icaB mutant strain was devoid of the ability to attach to the bacterial cell surface. Importantly, deacetylation of the polymer was essential for key virulence mechanisms of S. epidermidis, namely biofilm formation, colonization, and resistance to neutrophil phagocytosis and human antibacterial peptides. Furthermore, persistence of the icaB mutant strain was significantly impaired in a murine model of device-related infection. This is the first study to describe a mechanism of exopolysaccharide modification that is indispensable for the development of biofilm-associated human disease. Notably, this general virulence mechanism is likely similar for other pathogenic bacteria and constitutes an excellent target for therapeutic maneuvers aimed at combating biofilm-associated infection.
生物膜在许多慢性细菌感染中发挥着重要作用。产生一种称为胞外多糖的糖聚合物细胞外混合物是生物膜形成的特征且至关重要。然而，关于胞外多糖成分的生物合成和修饰机制以及这些过程如何影响细菌致病性的信息有限。表皮葡萄球菌是一种重要的人类病原体，经常通过在植入式医疗器械上形成生物膜而导致持续性感染。它产生一种聚-N-乙酰葡糖胺分子，该分子是许多细菌病原体胞外多糖的一种成分。我们使用基于尺寸排阻色谱-质谱的新方法证明，表面附着蛋白IcaB负责聚-N-乙酰葡糖胺分子的脱乙酰化。很可能由于其阳离子特性的丧失，同基因icaB突变株中的非脱乙酰化聚乙酰葡糖胺缺乏附着于细菌细胞表面的能力。重要的是，聚合物的脱乙酰化对于表皮葡萄球菌的关键毒力机制至关重要，即生物膜形成、定植以及对中性粒细胞吞噬作用和人类抗菌肽的抗性。此外，icaB突变株在与器械相关感染的小鼠模型中的持续性显著受损。这是第一项描述胞外多糖修饰机制的研究，该机制对于生物膜相关人类疾病的发展不可或缺。值得注意的是，这种一般毒力机制可能与其他致病细菌相似，并且构成了旨在对抗生物膜相关感染的治疗策略的极佳靶点。
