Regulation of the beta-lactamase BlaL of Streptomyces cacaoi: the product of the blaB regulatory gene is an internal membrane-bound protein

Cloning and sequence analysis of a class A beta-lactamase from Mycobacterium tuberculosis H37Ra

A cosmid library from Mycobacterium tuberculosis H37Ra was introduced into Mycobacterium smegmatis, and eight recombinant clones with increased resistance to cefoxitin were identified. Isoelectric focusing detected an M. tuberculosis-derived beta-lactamase in one of these recombinant clones. A sequence analysis identified it as a class A beta-lactamase whose expression correlated with the increased resistance phenotype.