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NmeSI restriction-modification system identified by representational difference analysis of a hypervirulent Neisseria

A Bart1, Y Pannekoek, J Dankert

  • 1Department of Medical Microbiology, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands. A.Bart@AMC.UVA.NL

Infection and Immunity
|February 17, 2001
PubMed

Insights

Lineage III *Neisseria meningitidis* strains, causing increased disease, possess a unique restriction-modification system. This system may enhance their virulence and spread by influencing gene transfer and transcription.

Area of Science:

  • Microbiology
  • Genetics
  • Molecular Biology

Background:

  • Neisseria meningitidis is a gram-negative bacterium responsible for meningitis and sepsis.
  • A rise in meningococcal disease incidence over two decades is linked to lineage III strains.
  • Genomic differences between lineage III and non-lineage III strains are not fully understood.

Purpose of the Study:

  • To identify genetic differences between lineage III and non-lineage III *Neisseria meningitidis* strains.
  • To characterize the specific genetic locus found in lineage III strains.
  • To investigate the functional role of the identified genetic element in lineage III meningococci.

Main Methods:

  • Representational difference analysis (RDA) to compare chromosomal DNA.
  • Identification and characterization of a specific 1.8-kb DNA locus.
  • Cloning and expression of a methyltransferase gene from the identified locus in *Escherichia coli*.

Main Results:

  • A 1.8-kb DNA locus, specific to lineage III meningococci, was identified.
  • This locus encodes the NmeSI restriction-modification system, including a methyltransferase gene.
  • The NmeSI enzyme was shown to modify the DNA site AGTACT.

Conclusions:

  • Lineage III meningococci are genetically distinct from endemic strains due to a specific restriction-modification system.
  • This NmeSI system may contribute to the hypervirulence and clonal nature of lineage III strains.
  • The restriction-modification system potentially influences horizontal gene transfer and transcription, impacting bacterial adaptation and pathogenesis.

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