Pepsin-mediated processing of the cytoplasmic histone H2A to strong antimicrobial peptide buforin I.

摘要: The intestinal epithelium forms a first line of innate host defense by secretion proteins with antimicrobial activity against microbial infection. Despite the extensive studies on in many gastrointestinal tracts, little is known about system stomach. potent peptide buforin I, consisting 39 aa, was isolated recently from stomach tissue an Asian toad, Bufo bufo gargarizans. In this study we examined mechanism I production toad tissue. Buforin produced action pepsin isozymes, named Ca and Cb, cleaving Tyr39-Ala40 bond histone H2A. Immunohistochemical analysis revealed that present extracellularly mucosal surface, unacetylated H2A, precursor localized cytoplasm gastric gland cells. Furthermore, Western blot showed also fluids, immunoelectron microscopy detected localization H2A cytoplasmic granules distinct subcellular distribution detection both surface lumen suggest secreted into subsequently processed pepsins. Our results indicate along pepsins vertebrate may contribute to invading microorganisms.