Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Proc Natl Acad Sci U S A. 2011 Aug 2;108(31):12887-92. doi: 10.1073/pnas.1108265108. Epub 2011 Jul 18.
Caenorhabditis elegans exhibits a diverse range of behaviors in response to bacteria. The presence of bacterial food influences C. elegans aerotaxis, aggregation, locomotion, and pathogen avoidance behaviors through the activity of the NPR-1 neuropeptide receptor. Here, we show that mucoid strains of bacteria that produce an exopolysaccharide matrix do not induce NPR-1-dependent behaviors. In the presence of mucoid strains of bacteria, the C. elegans laboratory wild-type (WT) strain N2 exhibits behaviors characteristic of wild isolates and mutants with reduced NPR-1 activity. Specifically, N2 exhibits lawn bordering and roaming behavior on mucoid nonpathogenic bacteria and loss of pathogen avoidance on mucoid Pseudomonas aeruginosa. Alginate biosynthesis by laboratory and clinical isolates of mucoid P. aeruginosa is necessary and sufficient to attenuate NPR-1-mediated behavior and it suppresses C. elegans pathogen avoidance behavior. Our data suggest that the specific interaction with nonmucoid bacteria induces NPR-1-dependent behaviors of C. elegans. These observations provide an example of how exopolysaccharide matrix biosynthesis by a community of bacteria may inhibit specific host responses to microbes.
秀丽隐杆线虫在面对细菌时会表现出多种多样的行为。通过 NPR-1 神经肽受体的活动，细菌食物的存在会影响秀丽隐杆线虫的趋气性、聚集性、运动性和病原体回避行为。在这里，我们发现产生胞外多糖基质的粘液菌菌株不会诱导 NPR-1 依赖性行为。在粘液菌菌株存在的情况下，秀丽隐杆线虫实验室野生型（WT）菌株 N2 表现出与 NPR-1 活性降低的野生分离株和突变体相似的行为。具体来说，N2 在粘液非致病性细菌上表现出草坪边界和漫游行为，而在粘液铜绿假单胞菌上则失去了病原体回避行为。粘液铜绿假单胞菌实验室和临床分离株的海藻酸钠生物合成是减弱 NPR-1 介导行为所必需和充分的，它抑制了秀丽隐杆线虫的病原体回避行为。我们的数据表明，与非粘液菌的特定相互作用诱导了秀丽隐杆线虫 NPR-1 依赖性行为。这些观察结果提供了一个例子，说明细菌群落的胞外多糖基质生物合成如何抑制宿主对微生物的特定反应。
