A lipoprotein signal peptide plus a cysteine residue at the amino-terminal end of the periplasmic protein β-lactamase is sufficient for its lipid modification, processing and membrane localization in Escherichia coli

Abstract By genetic exchange and in vitro mutagenesis a hybrid β-lactamase was constructed that contained the pCloDF13-encoded bacteriocin release protein signal peptide plus a cysteine residue coupled to the mature portion of β-lactamase. Immunoblotting, labelling with [³H]palmitate in the presence and absence of globomycin, and pulse-chase experiments revealed that this hybrid construct is modified with lipid and processed into a lipid-modified β-lactamase. Subcellular localization studies revealed that this hybrid is localized both in the cytoplasmic and outer membranes of Escherichia coli cells. A mutant derivative with an incomplete lipobox (LVG instead of LVAC⁺¹) was not processed and was found in the cytoplasmic membranes