SYNTHESIS OF RIBOSOMAL-PROTEINS DURING GROWTH OF STREPTOMYCES-COELICOLOR

Changes in expression of ribosomal protein genes during growth and sta tionary phase of Streptomyces coelicolor A3(2) in liquid medium were s tudied. Proteins being synthesized were pulse-labelled with [S-35]-met hionine, separated by two-dimensional polyacrylamide gel electrophores is, and quantified using the BioImage computer software. Most of the r ibosomal proteins were synthesized throughout the life cycle. Exceptio ns were two proteins whose synthesis drastically decreased at the appr oach of stationary phase. These two proteins were identified in purifi ed ribosomes as homologues of Escherichia coli ribosomal proteins L10 and L7/L12, using antibodies raised against fusion proteins between th ese ribosomal proteins and Escherichia coil P-galactosidase. The genes (rplJ and rplL) encoding the L10 and L7/L12 proteins were contained i n a 1.2kb BamHI fragment that was cloned and sequenced. The linkage an d order of the genes coincide with other L10-L7/L12 operons. However, L11 and L1 genes were not present immediately upstream of the L10 gene , as is the case for E. coli and other bacteria. Instead, two open rea ding frames of unknown function were found immediately upstream of the L10 gene, in an adjacent 1.9 kb BamHI fragment.