Conserved portion in bacterial ribosomal RNA

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• Bacterial ribosomal RNA (rRNA) plays a crucial role in protein synthesis.
• Understanding conserved regions in rRNA is vital for bacterial taxonomy and drug development.
• Previous studies have explored rRNA sequence homology, but detailed analysis of conserved portions remains important.

Purpose of the Study:

• To investigate the conserved regions within bacterial 23S ribosomal RNA (rRNA) using DNA-RNA hybridization.
• To quantify the extent of sequence similarity between Bacillus subtilis and Escherichia coli 23S rRNA.
• To characterize the properties of hybridized RNA molecules.

Main Methods:

• DNA-RNA hybridization was employed to assess sequence complementarity.
• Sucrose density gradient centrifugation and Sephadex gel filtration were used to estimate RNA chain lengths.
• Nucleotide composition analysis of hybridized RNA was performed.

Main Results:

• Hybridization percentages between homologous DNA and 23S rRNA were low (B. subtilis: 0.16%, E. coli: 0.15%).
• Heterologous hybridization (B. subtilis DNA with E. coli rRNA, and vice versa) yielded very low percentages (0.03% and 0.04%, respectively), indicating significant sequence divergence.
• Rehybridization of RNA from heterologous hybrids confirmed the presence of conserved sequences.
• Estimated average chain lengths of RNA in hybrids exceeded 30 nucleotides.
• RNA from hybrids showed higher molar percentages of guanylic acid and cytidylic acid compared to whole rRNA.

Conclusions:

• Bacterial 23S rRNA sequences, particularly between B. subtilis and E. coli, exhibit limited homology.
• Despite overall divergence, conserved nucleotide regions within the 23S rRNA exist.
• The characterized RNA fragments are substantial and possess distinct nucleotide compositions, suggesting functional significance of these conserved regions.