A complete lipopolysaccharide inner core oligosaccharide is required for resistance of Burkholderia cenocepacia to antimicrobial peptides and bacterial survival in vivo
A complete lipopolysaccharide inner core oligosaccharide is required for resistance of Burkholderia cenocepacia to antimicrobial peptides and bacterial survival in vivo
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DOI：
10.1128/jb.188.6.2073-2080.2006
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发表时间：
2006-03-01
影响因子：
3.2
通讯作者：
Valvano, MA
中科院分区：
文献类型：
--
作者：
Loutet, SA;Flannagan, RS;Valvano, MA
新洋葱伯克霍尔德菌是囊性纤维化患者的重要条件致病菌。这种细菌本质上对多种抗菌剂具有耐药性，包括高浓度的抗菌肽。我们推测B. cenocepacia对于抗微生物肽的毒力和抗性都是重要的。我们在B中鉴定了hldA和hldD基因。新洋葱菌株K56-2。这两个基因编码参与庚糖在掺入LPS核心寡糖之前的修饰的酶。我们构建了一个突变体，SAL 1，这是在hldA和hldD的表达缺陷，并通过进行互补研究，我们证实了这两个B编码的功能。合成完整的LPS核心寡糖需要cenocepacia基因。由SAL 1产生的LPS由短的脂质A-核心寡糖组成，并且不含0抗原。SAM对抗菌肽多粘菌素B、蜂毒素和人中性粒细胞肽1敏感。相比之下，另一个B.产生完全脂质A-核心寡糖但缺乏多聚0抗原的新洋葱属突变菌株对多粘菌素B或蜂毒肽不敏感。如通过肺感染的大鼠琼脂珠模型所确定的，SAL 1突变体在体内具有存活缺陷，因为它不能从感染后14天的感染大鼠的肺中恢复。总之，这些数据表明，B。新洋葱LPS内核寡糖是对三种结构上不相关的抗微生物肽的体外抗性和慢性肺部感染大鼠模型的体内存活所必需的。
Burkholderia cenocepacia is an important opportunistic pathogen of patients with cystic fibrosis. This bacterium is inherently resistant to a wide range of antimicrobial agents, including high concentrations of antimicrobial peptides. We hypothesized that the lipopolysaccha ride (LPS) of B. cenocepacia is important for both virulence and resistance to antimicrobial peptides. We identified hldA and hldD genes in B. cenocepacia strain K56-2. These two genes encode enzymes involved in the modification of heptose sugars prior to their incorporation into the LPS core oligosaccharide. We constructed a mutant, SAL1, which was defective in expression of both hldA and hldD, and by performing complementation studies we confirmed that the functions encoded by both of these B. cenocepacia genes were needed for synthesis of a complete LPS core oligosaccharide. The LPS produced by SAL1 consisted of a short lipid A-core oligosaccharide and was devoid of 0 antigen. SAM was sensitive to the antimicrobial peptides polymyxin B, melittin, and human neutrophil peptide 1. In contrast, another B. cenocepacia mutant strain that produced complete lipid A-core oligosaccharide but lacked polymeric 0 antigen was not sensitive to polymyxin B or melittin. As determined by the rat agar bead model of lung infection, the SAL1 mutant had a survival defect in vivo since it could not be recovered from the lungs of infected rats 14 days postinfection. Together, these data show that the B. cenocepacia LPS inner core oligosaccharide is needed for in vitro resistance to three structurally unrelated antimicrobial peptides and for in vivo survival in a rat model of chronic lung infection.