Coregulation of processing and translation: mature 5' termini of Escherichia coli 23S ribosomal RNA form in polysomes.

AUTOR(ES)

Srivastava, A K

RESUMO

In Escherichia coli, the final maturation of rRNA occurs in precursor particles, and recent experiments have suggested that ongoing protein synthesis may somehow be required for maturation to occur. The protein synthesis requirement for the formation of the 5' terminus of 23S rRNA has been clarified in vitro by varying the substrate of the reaction. In cell extracts, pre-23S rRNA in free ribosomes was not matured, but that in polysomes was efficiently processed. The reaction occurred in polysomes without the need for an energy source or other additives required for protein synthesis. Furthermore, when polysomes were dissociated into ribosomal subunits, they were no longer substrates for maturation; but the ribosomes became substrates again when they once more were incubated in the conditions for protein synthesis. All of these results are consistent with the notion that protein synthesis serves to form a polysomal complex that is the true substrate for maturation. Ribosomes in polysomes, possibly in the form of 70S initiation complexes, may more easily adopt a conformation that facilitates maturation cleavage. As a result, the rates of ribosome formation and protein synthesis could be coregulated.

Documentos Relacionados

• Escherichia coli 23S ribosomal RNA truncated at its 5' terminus.
• Extensions of the known sequences at the 3' and 5' ends of 23S ribosomal RNA from Escherichia coli, possible base pairing between these 23S RNA regions and 16S ribosomal RNA.
• Processing of the 5' end of Escherichia coli 16S ribosomal RNA.
• Ordered processing of Escherichia coli 23S rRNA in vitro.
• Divergent mechanisms of 5′ 23S rRNA IVS processing in the α-proteobacteria