Study for the factor involved in endotoxin ercognition

内毒素识别相关因素的研究

基本信息

批准号：
16590078
负责人：
KAWASAKI Kiyoshi
金额：
$ 2.24万
依托单位：
National Insititute of Infectious Diseases
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

项目摘要

Salmonella typhimurium remodels its outer membrane, including the lipid A component of lipopolysaccharide, to survive within animals. Activation of the sensor kinase PhoQ by host environments, promotes synthesis of enzymes that deacylate, palmitoylate, hydroxylate and attach aminoarabinose to lipid A, which is known as endotoxin. Deacylated- and/or palmitoylated-lipid A species were generated, and I examined their ability to induce cellular signaling through Toll-like receptor 4. The ability was reduced by the modifications, suggesting that the modifications are beneficial for bacteria to evade from host recognition.The Salmonellae lipid A 3-O-deacylase PagL, is an outer membrane protein whose expression is regulated by PhoQ. Upon PhoQ-activation, 3-O-deacylated lipid A species were not detected in S.typhimurium despite induction of the PagL expression. In contrast, strains defective for aminoarabinose modification of the outer membrane demonstrated in vivo PagL activity, indicating that this membrane modification inhibited PagL enzymatic activity. Since not all lipid A molecules are modified with aminoarabinose upon PhoQ-activation, these results suggested that PagL enzymatic deacylation was post-translationally inhibited by membrane environments sequestering PagL from its substrate or altering its conformations. PagL-dependent deacylation was detected in sonically disrupted membrane and membrane treated with octylglucoside, suggesting that damages of intact membrane releases PagL from the post-translational inhibition.

鼠伤寒沙门氏菌重塑其外膜，包括脂质的脂多糖成分，以在动物中生存。通过宿主环境激活传感器激酶PHOQ，促进脱酰酸盐，棕榈酸酯，羟基甲酯和氨基酰胺糖与脂质A的酶合成，以脂质A（称为内毒素）。 Deacylated- and/or palmitoylated-lipid A species were generated, and I examined their ability to induce cellular signaling through Toll-like receptor 4. The ability was reduced by the modifications, suggesting that the modifications are beneficial for bacteria to evade from host recognition.The Salmonellae lipid A 3-O-deacylase PagL, is an outer membrane protein whose expression is regulated by PhoQ. pHOQ激活后，尽管诱导了PAGL表达，但仍未检测到3-O-二甲基化的脂质A物种。相比之下，外膜的氨基氨基糖修饰有缺陷表现出体内PAGL活性，表明该膜修饰抑制了PAGL酶促活性。由于并非所有脂质A分子在phoQ激活后都用氨基酰胺糖修饰，因此这些结果表明PAGL酶促脱酰化在后翻译后被膜环境从其底物中隔离PAGL或改变其构象。在超声中断的膜和用辛基葡萄糖剂处理的膜中检测到PAGL依赖性脱酰化，这表明完整膜的损害可从翻译后抑制中释放PAGL。