title: Induction of chromosomal beta-lactamase expression in enterobacteria.
abstract: Enterobacteria and Pseudomonas express evolutionarily related chromosomally encoded beta-lactamases. These enzymes have a high affinity for modern cephalosporins, and beta-lactamase overproduction is the most important factor in the development of resistance against such drugs. In some species the beta-lactamase is produced constitutively at a low level, and mutations to high expression occur only infrequently. In other species beta-lactamase synthesis can be induced by beta-lactams, and mutation to constitutive overexpression of the enzyme is a frequent event. We discuss the current knowledge concerning the genetic basis of the two different modes of beta-lactamase regulation, as well as the mechanisms through which a high level of beta-lactamase synthesis is reached.
mesh_terms: D001483:Base Sequence; D002876:Chromosomes, Bacterial; D004755:Enterobacteriaceae / Q000201:enzymology* / Q000235:genetics; D004790:Enzyme Induction; D005786:Gene Expression Regulation; D011549:Pseudomonas / Q000201:enzymology* / Q000235:genetics; D001618:beta-Lactamases / Q000096:biosynthesis*
chemical_list: D001618:beta-Lactamases