Molecular Analysis of -Lactamases from Four Species of Streptomyces: Comparison of Amino Acid Sequences with those of other -clactamases

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Abstract
Genes encoding extracellular .beta.-lactamases of Streptomyces badius, Streptomyces cacaoi, Streptomyces fradiae and Streptomyces lavendulae were cloned and mapped in Streptomyces lividans. DNA sequence analysis of the .beta.-lactamase genes revealed a high overall G+C content, ranging from 71 to 75 mol%, with a G+C content of 95 mol% at the third position of the codons for all four genes. The primary structure of the .beta.-lactamases including their signal peptides was deduced. The four .beta.-lactamases exhibited homology to each other and to class A .beta.-lactamases from other bacterial genera. We suggest that Streptomyces .beta.-lactamases are representatives of a superfamily of genes, from which class A .beta.-lactamases of Gram-negative bacteria may have evolved.