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Analysis of the regulated transcriptome of Neisseria meningitidis in human blood using a tiling array
Elena Del Tordello1, Silvia Bottini, Alessandro Muzzi
1Novartis Vaccines and Diagnostics, Siena, Italy.
Abstract:
Neisseria meningitidis is the major cause of septicemia and meningococcal meningitis. During the course of infection, the bacterium must adapt to different host environments as a crucial factor for survival and dissemination; in particular, one of the crucial factors in N. meningitidis pathogenesis is the ability to grow and survive in human blood. We recently showed that N. meningitidis alters the expression of 30% of the open reading frames (ORFs) of the genome during incubation in human whole blood and suggested the presence of fine regulation at the gene expression level in order to control this step of pathogenesis. In this work, we used a customized tiling oligonucleotide microarray to define the changes in the whole transcriptional profile of N. meningitidis in a time course experiment of ex vivo bacteremia by incubating bacteria in human whole blood and then recovering RNA at different time points. The application of a newly developed bioinformatic tool to the tiling array data set allowed the identification of new transcripts--small intergenic RNAs, cis-encoded antisense RNAs, mRNAs with extended 5' and 3' untranslated regions (UTRs), and operons--differentially expressed in human blood. Here, we report a panel of expressed small RNAs, some of which can potentially regulate genes involved in bacterial metabolism, and we show, for the first time in N. meningitidis, extensive antisense transcription activity. This analysis suggests the presence of a circuit of regulatory RNA elements used by N. meningitidis to adapt to proliferate in human blood that is worthy of further investigation.
Insights
Neisseria meningitidis adapts to human blood by altering gene expression, including novel small RNAs and antisense transcripts. This discovery reveals a regulatory RNA network crucial for bacterial survival during infection.
Area of Science:
- Microbiology
- Genomics
- Molecular Biology
Background:
- Neisseria meningitidis causes severe infections like meningitis and septicemia.
- Bacterial adaptation to host environments, especially human blood, is critical for pathogenesis.
- Previous studies indicated significant gene expression changes in N. meningitidis during blood exposure.
Purpose of the Study:
- To comprehensively analyze the transcriptional profile of N. meningitidis in human blood over time.
- To identify novel transcripts and regulatory elements involved in adaptation to ex vivo bacteremia.
- To elucidate the role of small RNAs and antisense transcription in N. meningitidis pathogenesis.
Main Methods:
- Utilized a customized tiling oligonucleotide microarray for whole-transcriptome profiling.
- Conducted time-course experiments incubating N. meningitidis in human whole blood.
- Applied a novel bioinformatic tool for analyzing microarray data and identifying new transcripts.
Main Results:
- Identified differential expression of numerous transcripts, including small intergenic RNAs and cis-encoded antisense RNAs.
- Discovered mRNAs with extended 5' and 3' untranslated regions (UTRs) and novel operons.
- Reported extensive antisense transcription activity and a panel of expressed small RNAs with potential regulatory functions.
Conclusions:
- N. meningitidis employs a complex regulatory network involving small RNAs and antisense transcripts to adapt to human blood.
- This regulatory circuit is essential for bacterial proliferation and survival during infection.
- Further investigation into these RNA elements is warranted to understand N. meningitidis pathogenesis.
