Cloning of the rplA gene encoding ribosomal protein L1 from Streptomyces aureofaciens and its transcriptional analysis in the course of differentiation

Using the method for the identification of promoters recognized by the sporulation-specific σ factor RpoZ, we identified a positive 882-bp Sau3AI DNA fragment in Streptomyces aureofaciens. Sequence analysis revealed a complete open reading frame encoding a protein of 242 amino acids with a M_r of 25974. The deduced protein product showed high sequence similarity to all ribosomal proteins L1, with maximum similarity to several Streptomyces spp. L1 (97% identity). The 5′-truncated rplK gene encoding ribosomal protein L11 was located upstream of the rplA gene. However, the putative rpoZ-dependent promoter, P_ren25, was located divergently in the coding region of the rplA gene and was inactive in S. aureofaciens. To investigate expression of the rplA gene, Northern blot hybridization was performed using RNA prepared from S. aureofaciens in various developmental stages. These studies suggested that the rplA gene is expressed in all stages of differentiation as a 1400-nucleotides transcript. The amount of the transcript decreased during differentiation.