Dataset Information

Intervening sequence with conserved open reading frame in eubacterial 23S rRNA genes.

ABSTRACT: An intervening sequence (IVS) occurred in the 23S rRNA genes (rrl) of some, but not all, strains of four species of the spirochete genus Leptospira and was absent from strains in three other species. The IVS varied in size from 485 to 759 base pairs and replaced bases 1224-1245 in both copies of rrl. The two ends of each IVS shared 22-35 bases of complementarity that could form a stable double helix. The presence of an IVS correlated with a cleaved mature 23S rRNA that probably results from removal of the IVS without religation. The 3' site of cleavage was mapped within the inverted repeat of the IVS. An open reading frame of 121-133 amino acids was conserved in the IVS in all four species, oriented so that the sense strand was in the rRNA transcript. When the open reading frames were compared between species, they predicted polypeptides that showed between 51% and 78% amino acid conservation and similar DNA sequence conservation, indicating selection for protein function.

SUBMITTER: Ralph D

PROVIDER: S-EPMC47033 | biostudies-other | 1993 Jul

REPOSITORIES: biostudies-other

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Intervening sequence with conserved open reading frame in eubacterial 23S rRNA genes.

Ralph D D McClelland M M

Proceedings of the National Academy of Sciences of the United States of America 19930701 14

An intervening sequence (IVS) occurred in the 23S rRNA genes (rrl) of some, but not all, strains of four species of the spirochete genus Leptospira and was absent from strains in three other species. The IVS varied in size from 485 to 759 base pairs and replaced bases 1224-1245 in both copies of rrl. The two ends of each IVS shared 22-35 bases of complementarity that could form a stable double helix. The presence of an IVS correlated with a cleaved mature 23S rRNA that probably results from remo ...[more]

PMID: 8341711

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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

Intervening sequence with conserved open reading frame in eubacterial 23S rRNA genes.

Publications

Intervening sequence with conserved open reading frame in eubacterial 23S rRNA genes.

Similar Datasets

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