The invention relates generally to the field of molecular biology and microbiology. Provided herein is an expression construct encoding a fusion protein. In one embodiment, there is provided an expression construct encoding a fusion protein, the expression construct comprising a nucleic acid encoding a first polypeptide for expression and a second polypeptide derived from the cell wall targeting region of a Lactobacillus plantarum Lys2 autolysin, wherein the first and second polypeptides are joined to form a fusion protein. In a specific embodiment, the second polypeptide comprises the CAD4a domain, which is a truncated domain containing only R1-R3 of the five-repeat SH3_5 domain of the Lys2 autolysin. Provided herein is also a fusion protein and the use of a fusion protein as defined herein.