Patterns and regulation of ribosomal RNA transcription in <it>Borrelia burgdorferi</it>

<p>Abstract</p> <p>Background</p> <p><it>Borrelia burgdorferi </it>contains one 16S and two tandem sets of 23S-5S ribosomal (r) RNA genes whose patterns of transcription and regulation are unknown but are likely to be critical for survival and persistence in its hosts.</p> <p>Results</p> <p>RT-PCR of <it>B. burgdorferi </it>N40 and B31 revealed three rRNA region transcripts: 16S rRNA-alanine transfer RNA (tRNA^Ala); tRNA^Ile; and both sets of 23S-5S rRNA. At 34°C, there were no differences in growth rate or in accumulation of total protein, DNA and RNA in B31 cultured in Barbour-Stoenner-Kelly (BSK)-H whether rabbit serum was present or not. At 23°C, B31 grew more slowly in serum-containing BSK-H than at 34°C. DNA per cell was higher in cells in exponential as compared to stationary phase at either temperature; protein per cell was similar at both temperatures in both phases. Similar amounts of rRNA were produced in exponential phase at both temperatures, and rRNA was down-regulated in stationary phase at either temperature. Interestingly, a <it>rel_Bbu</it>deletion mutant unable to generate (p)ppGpp did not down-regulate rRNA at transition to stationary phase in serum-containing BSK-H at 34°C, similar to the relaxed phenotype of <it>E. coli relA </it>mutants.</p> <p>Conclusions</p> <p>We conclude that rRNA transcription in <it>B. burgdorferi </it>is complex and regulated both by growth phase and by the stringent response but not by temperature-modulated growth rate.</p>

Abstract licence: CC BY-NC-ND

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