Bactericidal Permeability-Increasing Proteins Shape Host-Microbe Interactions

摘要: We characterized bactericidal permeability-increasing proteins (BPIs) of the squid Euprymna scolopes, EsBPI2 and EsBPI4. They have molecular characteristics typical other animal BPIs, are closely related to one another, nest phylogenetically among invertebrate BPIs. Purified EsBPIs had antimicrobial activity against squid's symbiont, Vibrio fischeri, which colonizes light organ crypt epithelia. Activity both was abrogated by heat treatment coincubation with specific antibodies. Pretreatment under acidic conditions similar those during symbiosis initiation rendered V. fischeri more resistant proteins. Immunocytochemistry localized symbiotic epithelial surfaces interacting ambient seawater. The differed in intracellular distribution. Further, whereas EsBPI4 restricted epithelia, also occurred blood a transient juvenile that mediates hatching. data provide evidence these BPIs play different defensive roles early life E. modulating interactions symbiont.IMPORTANCE This study describes new functions for (BPIs), members lipopolysaccharide-binding protein (LBP)/BPI family. dual role modulation bacteria. In squid-vibrio model, control symbiont populations tissues where cells occur dense monoculture and, concomitantly, inhibit from colonizing animal.