Identification of a general O-linked protein glycosylation system in Acinetobacter baumannii and its role in virulence and biofilm formation.
Identification of a general O-linked protein glycosylation system in Acinetobacter baumannii and its role in virulence and biofilm formation.
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DOI：
10.1371/journal.ppat.1002758
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发表时间：
2012
期刊：
影响因子：
6.7
通讯作者：
Feldman MF
中科院分区：
文献类型：
--
作者：
Iwashkiw JA;Seper A;Weber BS;Scott NE;Vinogradov E;Stratilo C;Reiz B;Cordwell SJ;Whittal R;Schild S;Feldman MF
鲍曼不动杆菌是一种新出现的医院感染的原因。对多种抗生素耐药的菌株的分离正在以惊人的速度增加。尽管A.鲍曼不动杆菌被认为是对我们的医疗保健系统更具威胁性的“超级细菌之一，但对其致病因素知之甚少。在这项工作中，我们表明，A.鲍曼不动杆菌ATCC 17978具有负责多种蛋白质糖基化的O-糖基化系统。2D-DIGE和质谱鉴定了7个A.功能未知的鲍曼不动杆菌糖蛋白。使用MS和NMR技术的组合测定聚糖结构，其由含有N-乙酰半乳糖胺、葡萄糖、半乳糖、N-乙酰葡糖胺和葡萄糖醛酸衍生物的支链五糖组成。通过同源重组产生糖基化缺陷菌株。该菌株没有显示出任何生长缺陷，但表现出产生生物膜的能力严重降低。破坏的糖基化机制也导致在两种感染模型，变形虫Dictyosteelium discoideum和幼虫的昆虫大蜡螟的毒力降低，并减少在体内健身的小鼠模型腹膜败血症。尽管A.由于鲍曼不动杆菌基因组的可塑性，O-糖基化机制似乎存在于所有测试的临床分离株以及所有测序的基因组中。这表明存在一种强大的进化压力来保留这种系统。这些结果共同表明A.鲍曼不动杆菌是完全毒力所必需的，因此代表了开发新抗生素的新靶点。多重耐药（MDR）鲍曼不动杆菌菌株是全球医院感染的一个日益增长的原因。由于A.鲍曼不动杆菌对抗生素产生抗药性，这种细菌现在被认为是“超级细菌。A.也已经分离出对所有已知的临床相关抗生素具有抗性的鲍曼不动杆菌菌株。虽然MDR A.鲍曼不动杆菌仍在全球范围内传播，但其致病机制尚不清楚。实验结果表明，A.鲍曼不动杆菌ATCC 17978具有功能性O-连接蛋白糖基化系统，该系统似乎存在于所有鲍曼不动杆菌菌株中。鲍曼不动杆菌和几个临床分离株。我们鉴定了7种糖蛋白，并阐明了聚糖部分的结构。产生了糖基化缺陷菌株。该菌株产生严重减少的生物膜，并在阿米巴、昆虫和小鼠模型中表现出减弱的毒力。这些实验表明，糖基化可能在毒力中发挥重要作用，并可能为新药发现策略奠定基础，这些策略可以阻止这种新兴的人类病原体的传播，这种病原体已成为医疗保健系统的主要威胁。
Acinetobacter baumannii is an emerging cause of nosocomial infections. The isolation of strains resistant to multiple antibiotics is increasing at alarming rates. Although A. baumannii is considered as one of the more threatening “superbugs” for our healthcare system, little is known about the factors contributing to its pathogenesis. In this work we show that A. baumannii ATCC 17978 possesses an O-glycosylation system responsible for the glycosylation of multiple proteins. 2D-DIGE and mass spectrometry methods identified seven A. baumannii glycoproteins, of yet unknown function. The glycan structure was determined using a combination of MS and NMR techniques and consists of a branched pentasaccharide containing N-acetylgalactosamine, glucose, galactose, N-acetylglucosamine, and a derivative of glucuronic acid. A glycosylation deficient strain was generated by homologous recombination. This strain did not show any growth defects, but exhibited a severely diminished capacity to generate biofilms. Disruption of the glycosylation machinery also resulted in reduced virulence in two infection models, the amoebae Dictyostelium discoideum and the larvae of the insect Galleria mellonella, and reduced in vivo fitness in a mouse model of peritoneal sepsis. Despite A. baumannii genome plasticity, the O-glycosylation machinery appears to be present in all clinical isolates tested as well as in all of the genomes sequenced. This suggests the existence of a strong evolutionary pressure to retain this system. These results together indicate that O-glycosylation in A. baumannii is required for full virulence and therefore represents a novel target for the development of new antibiotics. Multidrug resistant (MDR) Acinetobacter baumannii strains are an increasing cause of nosocomial infections worldwide. Due to the remarkable ability of A. baumannii to gain resistance to antibiotics, this bacterium is now considered to be a “superbug”. A. baumannii strains resistant to all clinically relevant antibiotics known have also been isolated. Although MDR A. baumannii continues to disseminate globally, very little is known about its pathogenesis mechanisms. Our experiments revealed that A. baumannii ATCC 17978 has a functional O-linked protein glycosylation system, which seems to be present in all strains of A. baumannii sequenced to date and several clinical isolates. We identified seven glycoproteins and elucidated the structure of the glycan moiety. A glycosylation-deficient strain was generated. This strain produced severely reduced biofilms, and exhibited attenuated virulence in amoeba, insect, and murine models. These experiments suggest that glycosylation may play an important role in virulence and may lay the foundation for new drug discovery strategies that could stop the dissemination of this emerging human pathogen, which has become a major threat for healthcare systems.
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影响因子：
3.7
作者：
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作者：
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影响因子：
15.3
作者：
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