Identification and characterization of adhesion proteins in lactobacilli targeting actin as receptor

Actin as the main constitution of cytoskeleton in host cells plays an important role in mediating bacterial colonization. To identify the actin-binding proteins in Lactobacillus (L.) paracasei, L. plantarum, and L. brevis, actin immobilized to 24-well plate was used to probe adhesion proteins. Five adhesion proteins were identified and characterized by electrophoresis and LC-MS/MS: pyruvate kinase (PK), glucose-6-phosphate isomerase (PGI), phosphoglycerate kinase (PGK), chaperonin GroEL, and EF-Tu, all of which could display on the cell surface, indicating their possible role in mediating bacterial adhesion to host. This is in accordance with previous studies, which reported that these five proteins participated in and promoted the adhesion of pathogen or lactic acid bacteria to host. Moreover, PGK-actin binding domain analysis reveals that lysine (K) at amino acid position 127 in PGK might play a key role in mediating bacterial attachment to actin.