DISTRIBUTION IN THE GENUS STREPTOMYCES OF A HOMOLOG TO NUSG, A GENE ENCODING A TRANSCRIPTIONAL ANTITERMINATOR

The presence of the vbrA gene encoding the transcriptional antitermina tor NusG equivalent protein of Streptomyces virginiae was tested for i n 73 Streptomyces species by Southern hybridization. Fifty-five strain s (75%) including S. griseus, S. lividans TK-21 and S. coelicolor A3(2 ) showed clear hybridization signals, indicating wide distribution of vbrA or vbrA homologs in Streptomyces species. With hybridization patt erns against 3 different probes, i.e., probes covering vbrA alone, the downstream gene rplK alone, and both vbrA-rplK, the 55 strains were c lassified into 4 groups. In the groups I, II and III (total 50 strains ) vbrA was found to be adjacent to rplK, indicating that the gene arra ngement vbrA-rplK is common in Streptomyces and that these genes may c onstitute a part of gene cluster encoding several components of the tr anscription and translation apparatus, as in Escherichia coli.