Jiang Haobo, Ma Congcong, Lu Zhi-Qiang, Kanost Michael R
Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA.
Insect Biochem Mol Biol. 2004 Jan;34(1):89-100. doi: 10.1016/j.ibmb.2003.09.006.
We have isolated and characterized a new beta-1,3-glucan recognition protein that is present in Manduca sexta cuticle and hemolymph. This 52 kDa protein, designated betaGRP-2, is 57% identical in sequence to betaGRP-1 from larval hymolymph of the same insect. BetaGRP-2 differs from betaGRP-1 in its absence of the naive larvae before the wandering stage begins. Transcription of the betaGRP-2 was up-regulated in larvae challenged with yeast or bacteria. BetaGRP-2 contains a region with sequence similarity to several glucanases but lacks glucanase activity. It aggregates yeasts and bacteria to, perhaps, limit the spread of invading cells and ensure a localized defense reaction. BetaGRP-2 binds laminarin and lipoteichoic acid, but not lipopolysaccharide. Laminarin-triggered prophenoloxidase activation was greatly enhanced in the induced larval hemolymph supplemented with purified betaGRP-2. Complementing other studies on pattern recognition molecules in M. sexta, these results indicate that a complex system of protein sensors is an integral component of the insect immune system and that different recognition molecules have overlapping binding specificity and functions.
我们已经分离并鉴定了一种新的β-1,3-葡聚糖识别蛋白，它存在于烟草天蛾的表皮和血淋巴中。这种52 kDa的蛋白被命名为βGRP-2，其序列与来自同一种昆虫幼虫血淋巴中的βGRP-1有57%的同源性。βGRP-2与βGRP-1的不同之处在于，在漫游阶段开始之前的幼稚幼虫中不存在βGRP-2。在用酵母或细菌攻击的幼虫中，βGRP-2的转录上调。βGRP-2包含一个与几种葡聚糖酶序列相似的区域，但缺乏葡聚糖酶活性。它聚集酵母和细菌，可能是为了限制入侵细胞的扩散，并确保局部防御反应。βGRP-2结合海带多糖和脂磷壁酸，但不结合脂多糖。在添加了纯化的βGRP-2的诱导幼虫血淋巴中，海带多糖触发的前酚氧化酶激活大大增强。这些结果补充了对烟草天蛾模式识别分子的其他研究，表明蛋白质传感器的复杂系统是昆虫免疫系统的一个组成部分，并且不同的识别分子具有重叠的结合特异性和功能。
