Dataset Information

Functional Escherichia coli 23S rRNAs containing processed and unprocessed intervening sequences from Salmonella typhimurium.

ABSTRACT: We have introduced the intervening sequence (IVS) from 23S rRNA of the rrnD operon of Salmonella typhimurium into the equivalent position of Escherichia coli 23S rRNA. Salmonella typhimurium 23S rRNA is fragmented due to the RNase III-dependent removal of the approximately 100 nt stem-loop structure that comprises the IVS. In this study, we have found that insertion of the S. typhimurium IVS into E. coli 23S rRNA causes fragmentation of the RNA but does not affect ribosome function. Cells expressing the fragmented 23S rRNA exhibited wild-type growth rates. Fragmented RNA was found in the actively translating polysome pool and did not alter the sedimentation profile of ribosomal subunits, 70S ribosomes or polysomes. Finally, hybrid 23S rRNA carrying the A2058G mutation conferred high level erythromycin resistance indistinguishable from that of intact 23S rRNA carrying this mutation. These observations indicate that the presence of this IVS and its removal are phenotypically silent. As observed in an RNase III-deficient strain, processing of the IVS was not required for the production of functional ribosomes.

SUBMITTER: Gregory ST

PROVIDER: S-EPMC146334 | biostudies-other | 1996 Dec

REPOSITORIES: biostudies-other

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Functional Escherichia coli 23S rRNAs containing processed and unprocessed intervening sequences from Salmonella typhimurium.

Gregory S T ST O'Connor M M Dahlberg A E AE

Nucleic acids research 19961201 24

We have introduced the intervening sequence (IVS) from 23S rRNA of the rrnD operon of Salmonella typhimurium into the equivalent position of Escherichia coli 23S rRNA. Salmonella typhimurium 23S rRNA is fragmented due to the RNase III-dependent removal of the approximately 100 nt stem-loop structure that comprises the IVS. In this study, we have found that insertion of the S. typhimurium IVS into E. coli 23S rRNA causes fragmentation of the RNA but does not affect ribosome function. Cells expres ...[more]

PMID: 9016661

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Project description:Histophilus somni is a Gram-negative bacterial organism that acts as an opportunistic pathogen and is a fastidious member of the Pasteurellaceae family associated with diseases of respiratory, reproductive, cardiac, and other tissues of ruminants. We identified an intervening sequence (IVS) embedded in all five copies of the 23S rRNA gene in the closed genome sequence of the H. somni isolate USDA-ARS-USMARC-63250 that may play an important role in affecting the biology of the organism. Sequencing the RNA from this isolate shows that most of the IVS is cleaved from the transcript, resulting in independent fragments of this structural rRNA that remain functional within the bacterial ribosome. The IVS lies between positions 1170 and 1278 bp of the 3,017-bp gene and exhibits self-complementarity between its 5' and 3' ends that predicts a stem-loop structure interrupting helix-45 in the transcribed 23S rRNA. Excision removes a 94-nucleotide (nt) stem-loop structure that displays an unusual 1-nt 3' end overhang instead of the more typical 2-nt overhang commonly observed at the ends of other excised IVS stem-loops. A comparison with genomes of other H. somni isolates indicates that this IVS is highly conserved, with 31 of 32 complete genomes having similar interruptions of canonical 23S rRNA genes. The potential biological effects of either the released IVS or the fragmentation of the functional 23S rRNA are unknown, but fragmentation may enhance rRNA degradation in ways that contribute to the regulation of gene expression. IMPORTANCE The genome biology underlying H. somni virulence, pathogenicity, environmental adaptability, and broad tissue tropism is understood poorly. We identified a novel H. somni 109-nt IVS stem-loop structure, of which the central portion is excised from the 23S rRNA transcript, resulting in the fragmentation of this rRNA in the H. somni isolate USDA-ARS-USMARC-63250 and the release of a 94-nt structured RNA of unknown function. We determined that this peculiar rRNA biology is widespread among sequenced H. somni isolates, suggesting it has importance to organism biology. The fragmented 23S rRNA molecules remain functional in the ribosome, given that the isolate grows in culture. The structured excised portion of the IVS, presumably due to the action of the endoribonuclease III, has an unusual 1-nt 3' end overhang. This newly discovered H. somni 23S rRNA fragmentation may enhance rRNA degradation providing a previously unrecognized avenue for regulating H. somni biological processes.

Dataset Information

Functional Escherichia coli 23S rRNAs containing processed and unprocessed intervening sequences from Salmonella typhimurium.

Publications

Functional Escherichia coli 23S rRNAs containing processed and unprocessed intervening sequences from Salmonella typhimurium.

Similar Datasets

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