A LIPOPROTEIN SIGNAL PEPTIDE PLUS A CYSTEINE RESIDUE AT THE AMINO-TERMINAL END OF THE PERIPLASMIC PROTEIN BETA-LACTAMASE IS SUFFICIENT FOR ITS LIPID MODIFICATION, PROCESSING AND MEMBRANE LOCALIZATION IN ESCHERICHIA-COLI

By genetic exchange and in vitro mutagenesis a hybrid beta-lactamase was constructed that contained the pCloDF13-encoded bacteriocin release protein signal peptide plus a cysteine residue coupled to the mature portion of beta-lactamase. Immunoblotting, labelling with [H-3]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 beta-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