EXPRESSION AND ANALYSIS OF 2 GYRB GENES FROM THE NOVOBIOCIN PRODUCER,STREPTOMYCES-SPHAEROIDES

A novobiocin producer, Streptomyces sphaeroides, contains two genes, d esignated gyrB(S) and gyrB(R), that encode novobiocin-sensitive and -r esistant DNA gyrase B proteins, respectively. The cloning of gyrB(R) w as reported earlier; here, we describe the cloning of gyrB(S). Both ge nes have been sequenced (the deduced products of gyrB(S) and gyrB(R) h ave M(r) values of 87.6 K and 86.5 K, respectively) and their transcri pts have been mapped. Downstream of gyrB(S), and co-transcribed with i t, is the sole gyrA gene (encoding DNA gyrase A protein). By construct ing hybrid gyrB genes, using fragments of gyrB(S) and gyrB(R), a speci fic portion of the N-terminal domain of the gyrase B protein (correspo nding to amino acid residues 134-256 of Escherichia coli gyrase B) has been implicated in the binding of novobiocin.