Design of a novel affinity probe using the cell wall-binding domain of a Listeria monocytogenes autolysin for...

Human listeriosis is caused by consuming foods contaminated with the bacterial pathogen Listeria monocytogenes, leading to the development of a severe and life-threatening foodborne illness. Detection of L. monocytogenes present in food and food processing environments is crucial for preventing Listeria infection. The L. monocytogenes peptidoglycan hydrolase IspC anchors non-covalently to the bacterial surface through its C-terminal cell wall-binding domain (CWBD), CWBD_IspC. This study explored the surface binding property of CWBD_IspC to design, construct, characterize, and assess an affinity molecular probe for detecting L. monocytogenes. CWBD_IspC recognized a cell wall ligand lipoteichoic acid that remains evenly displayed and mostly unoccupied on the bacterial surface for interaction with the exogenously added CWBD_IspC. CWBD_IspC, when fused to the enhanced green fluorescent protein reporter or covalently conjugated onto magnetic beads, exhibited the functionality as an antibody alternative for rapid detection and efficient separation of the pathogen.