Screening and verification of outer membrane proteins of Cronobacter sakazakii with potential adhesion capability to human ileocecal adenocarcinoma cells

Abstract

Cronobacter sakazakii (C. sakazakii), a food-borne pathogen, can cause severe intestinal diseases, such as intestinal damage and necrotizing enterocolitis, and even death in neonates and infants through its adhesion to intestinal epithelium cells by protein-protein interaction and translocation across the intestinal barrier. Nevertheless, the mechanisms of adhesion, translocation, and pathogenesis remain unclear. This study aimed to screen and validate the outer membrane proteins of C. sakazakii capable of adhering to the surface of intestinal cells through biotinylated protein adhesion and LC-MS/MS identification. A total of 319 proteins were identified. Gene Ontology and KEGG analysis revealed significant enrichment of ligand proteins in metabolism-related processes and catalytic activity. The identified 37 outer membrane proteins and 41 proteins of unknown subcellular localization or function mainly enriched in five protein-protein interaction clusters. Ten of these outer membrane/unknown proteins were selected to test their roles on C. sakazakii adhesion and invasion of intestinal cells by silencing the encoding gene expression and nine of the ten proteins, Protein_26/30/34/38/42/98/104/194/282, were shown to be critical in this process. This study contributes to the understanding of proteins involved in the host adhesion process by C. sakazakii as well as the mechanisms for its translocation across the intestinal barrier.