CLONING AND TRANSCRIPTIONAL ANALYSIS OF THE RPLKA-ORF31-RPLJL GENE-CLUSTER OF STREPTOMYCES-GRISEUS

A 5018-bp DNA fragment of the rpl/rpoBC gene cluster (here called the rif cluster) of Streptomyces griseus N2-3-11 was analysed by DNA seque ncing and transcription studies. By sequence comparison of the deduced proteins, five genes and part of an open reading frame (orf) were ide ntified. The genes encoding the ribosomal (r-) proteins LI (rplA), L7/ 12 (rplJ), L10 (rplK) and L11 (rplL), a protein of unknown function (o rf31), and the N-terminus of the beta subunit of RNA polymerase (rpoB) , are organised in three operons, rplKA, rplJL and rpoB(C), and the mo nocistronic transcription unit orf31. The promoters of these transcrip tion units, rplKp, orf31p, rplJp, and rpoBp, were identified and the g rowth-phase dependence of the transcription of these operons was analy sed. Binding sites for the ribosomal proteins L1 and L10 were identifi ed by sequence comparison, suggesting that the r-proteins Rp1A and Rp1 J are involved in feedback regulation of their respective operons by b inding to specific RNA-binding sites present in both the mRNA and the 23S rRNA, as has been described for other bacteria. The analyses of th e rpoBp promoter by means of promoter-probe plasmids suggested a possi ble attenuator-based regulatory mechanism for the transcription of the rpoB(C) operon.