The Effects of Ribosomal Proteins uS2, uS3, and uS4 on Transcription

Abstract

In E. coli, transcription and translation are coupled and ribosomes can directly contact RNA polymerase. The contacts are formed between the RNA exit site of the RNA polymerase and ribosomal proteins uS2, uS3, or uS4 on the ribosome. We assessed the effects of ribosomal proteins uS2, uS3, and uS4 on transcription. In varying degrees, they all reduced termination and increased pausing. Although uS2 bound directly to the polymerase, it affected transcription the least. uS3, which did not bind the polymerase, had the most prominent effects on transcription. We suggest uS2 acts as an anchor for the polymerase during coupling of transcription and translation. Likewise, uS3 and uS4 may affect transcription depending on the length of RNA between the ribosome and polymerase. We speculate that ribosomal proteins may also coordinate the transcription of ribosomal RNAs with their assembly into ribosomes. Finally, we submit that the intrinsic effects of ribosomal proteins may drive the tight regulation of their expression in the cell.