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Ribonuclease III-mediated processing of specific Neisseria meningitidis mRNAs

Eliana De Gregorio1, Chiara Abrescia, M Stella Carlomagno

  • 1Dipartimento di Biologia e Patologia Cellulare e Molecolare L. Califano, Università degli Studi di Napoli Federico II, Via S. Pansini 5, 80131 Napoli, Italy.

The Biochemical Journal
|June 27, 2003
PubMed

Insights

Neisseria meningitidis Correia (nemis) elements are processed by RNase III, but specific terminal repeat sequences can inhibit this cleavage. This regulation impacts mRNA levels and stability.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Genetics

Background:

  • Neisseria meningitidis possesses small DNA insertion sequences called nemis elements, comprising ~2% of its genome.
  • These nemis elements feature terminal inverted repeats (TIRs) of 26-27 base pairs.
  • Nemis elements are co-transcribed with flanking genes, and resulting mRNAs are processed at double-stranded RNA structures formed by TIRs.

Purpose of the Study:

  • To investigate the processing of nemis+ RNAs by N. meningitidis RNase III.
  • To determine the role of TIR sequence complementarity in RNA hairpin processing.
  • To understand how nemis element processing affects mRNA levels and stability.

Main Methods:

  • In vitro cleavage assays using N. meningitidis RNase III.
  • Electrophoretic mobility shift assays (EMSA) to study protein-RNA interactions.
  • Analysis of mRNA levels and RNA stability in vivo and in vitro.

Main Results:

  • N. meningitidis RNase III efficiently cleaves RNA hairpins formed by nemis elements with identical TIRs (26/26 and 27/27 bp).
  • Hairpins formed by mismatched TIRs (26/27 bp) inhibit RNase III cleavage both in vitro and in vivo.
  • All hairpin types formed similar complexes with RNase III in EMSA, suggesting binding is not the sole determinant of cleavage.
  • Variations in nemis+ and nemis- mRNA levels and in vitro RNA segment stability were observed.

Conclusions:

  • RNase III-mediated processing of nemis+ RNAs is sequence-dependent, regulated by TIR complementarity.
  • Mismatched TIRs in nemis elements can inhibit processing, potentially influencing gene expression.
  • The findings highlight a novel regulatory mechanism impacting mRNA processing and stability in N. meningitidis.

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