Cloning and transcriptional analysis of the rplKA-or f31-rplJL gene cluster of Streptomyces griseus

Abstract

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 sequencing and transcription studies. By sequence comparison of the deduced proteins, five genes and part of an open reading frame (orf ) were identified. The genes encoding the ribosomal (r-) proteins L1 (rplA), L7/12 (rplJ ), L10 (rplK ) and L11 (rplL), a protein of unknown function (orf31), and the N-terminus of the β subunit of RNA polymerase (rpoB), are organised in three operons, rplKA, rplJL and rpoB(C), and the monocistronic transcription unit orf31. The promoters of these transcription units, rplKp, orf31p, rplJp, and rpoBp, were identified and the growth-phase dependence of the transcription of these operons was analysed. Binding sites for the ribosomal proteins L1 and L10 were identified by sequence comparison, suggesting that the r-proteins RplA and RplJ are involved in feedback regulation of their respective operons by binding to specific RNA-binding sites present in both the mRNA and the 23S rRNA, as has been described for other bacteria. The analyses of the rpoBp promoter by means of promoter-probe plasmids suggested a possible attenuator-based regulatory mechanism for the transcription of the rpoB(C) operon.