AMPLIFICATION OF THE BACA GENE CONFERS BACITRACIN RESISTANCE TO ESCHERICHIA-COLI

An Escherichia coli genomic library was constructed in order to facili tate selection for genes which confer bacitracin resistance through am plification. One of the plasmids from the library, plasmid pXV62, prov ided a high level of bacitracin resistance for E. coli. Deletion and n ucleotide sequence analyses of bacitracin resistance plasmid pXV62 rev ealed that a single open reading frame, designated the bacA gene, was sufficient for antibiotic resistance. The bacA gene mapped to approxim ately 67 min on the E. coli chromosome by proximity to a previously ma pped locus. The deduced amino acid sequence of the bacA-encoded protei n suggests an extremely hydrophobic protein of 151 amino acids, approx imately 65% of which were nonpolar amino acids. E. coli cells containi ng plasmid pXV62 have increased isoprenol kinase activity. The physica l characteristics of the deduced protein and enhanced lipid kinase act ivity suggest that the bacA gene may confer resistance to bacitracin b y phosphorylation of undecaprenol.