Deletions in the tL structure upstream to the rRNA genes in the E. coli rrnB operon cause transcription polarity.

AUTOR(ES)

Zacharias, M

RESUMO

A number of deletions have been constructed within the leader region of the rrnB operon from E. coli. The deletions remove a potential transcription terminator structure downstream from an antitermination recognition sequence (Box A), which precedes the structural gene for the 16S RNA. Cells harbouring plasmids, where the terminator structure was deleted, partially or totally, showed a reduction in growth rate under minimal growth conditions. Measurement of the ribosomal RNA synthesis rates of such cells determined by pulselabeling and hybridisation to appropriate DNA probes, showed that the amount of the more distally located 23S RNA was reduced compared to the promoter-proximal 16S RNA. This polarity in transcription, resulting in a non-stoichiometric synthesis of the ribosomal RNAs, is most likely the result of a defective antitermination. The reduction in the amount of 23S RNA in such cells is compensated for by an increase in the overall ribosomal RNA synthesis, in concordance with the ribosomal RNA feedback regulation model. The accumulation of transcripts of the tRNAGlu2 gene, coded in the spacer region between the 16S and 23S RNA genes, in cells with an altered rRNA stoichiometry supports this interpretation.

Documentos Relacionados

• Fusion of the promoter region of rRNA operon rrnB to lac Z gene.
• In vivo translation of a region within the rrnB 16S rRNA gene of Escherichia coli.
• The tRNAGlu2 gene in the rrnB operon of E. coli is a prerequisite for correct RNase III processing in vitro.
• Characterization of an rRNA Operon (rrnB) of Mycobacterium fortuitum and Other Mycobacterial Species: Implications for the Classification of Mycobacteria
• Point mutations in the leader boxA of a plasmid-encoded Escherichia coli rrnB operon cause defective antitermination in vivo.