Chlamydial rRNA operons: gene organization and identification of putative tandem promoters.

AUTOR(ES)

Engel, J N

RESUMO

We isolated and characterized the rRNA operons of murine Chlamydia trachomatis. By exhaustively screening a library of chlamydial DNA and by blot hybridization of genomic DNA, we showed that there are only two rRNA operons in C. trachomatis. S1 nuclease protection and primer extension analysis were used to map the 5' and 3' ends of the mature 16S and 23S transcripts in both rRNA cistrons and, additionally, to demonstrate the lack of intervening sequences in these genes. The 5' ends of the presumed primary rRNA transcript were located and found to originate at two tandem sites separated by 100 base pairs. The two tandem chlamydial rDNA transcripts were not differentially regulated. Their products were coordinately expressed and were detectable as early as 9 h postinfection. However, the upstream transcript was only 10% as abundant as the downstream transcript. The sequences surrounding the transcription initiation sites bore little homology with each other or with the classic Escherichia coli -10 and -35 promoter sequences. This finding suggests that chlamydial transcription signals may differ from those of previously studied procaryotes.

Documentos Relacionados

• In vitro transcription initiation of the spinach chloroplast 16S rRNA gene at two tandem promoters.
• Mapping and spacer identification of rRNA operons of Salmonella typhimurium.
• Efficient read-through of Tn9 and IS1 by RNA polymerase molecules that initiate at rRNA promoters.
• Rates and Consequences of Recombination between rRNA Operons
• Instability of rRNA Operons in Bacillus subtilis