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Updated: Jun 8, 2026
Combined Nucleotide and Protein Extractions in Caenorhabditis elegans
Published on: March 17, 2019
Neisseria meningitidis rifampicin resistant strains: analysis of protein differentially expressed
Arianna Neri1, Giuseppina Mignogna, Cecilia Fazio
1Department of Infectious, Parasitic and Immune-mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
Background:
Several mutations have been described as responsible for rifampicin resistance in Neisseria meningitidis. However, the intriguing question on why these strains are so rare remains open. The aim of this study was to investigate the protein content and to identify differential expression in specific proteins in two rifampicin resistant and one susceptible meningococci using two-dimensional electrophoresis (2-DE) combined with mass spectrometry.
Results:
In our experimental conditions, able to resolve soluble proteins with an isoelectric point between 4 and 7, twenty-three proteins have been found differentially expressed in the two resistant strains compared to the susceptible. Some of them, involved in the main metabolic pathways, showed an increased expression, mainly in the catabolism of pyruvate and in the tricarboxylic acid cycle. A decreased expression of proteins belonging to gene regulation and to those involved in the folding of polypeptides has also been observed. 2-DE analysis showed the presence of four proteins displaying a shift in their isoelectric point in both resistant strains, confirmed by the presence of amino acid changes in the sequence analysis, absent in the susceptible.
Conclusions:
The analysis of differentially expressed proteins suggests that an intricate series of events occurs in N. meningitidis rifampicin resistant strains and the results here reported may be considered a starting point in understanding their decreased invasion capacity. In fact, they support the hypothesis that the presence of more than one protein differentially expressed, having a role in the metabolism of the meningococcus, influences its ability to infect and to spread in the population. Different reports have described and discussed how a drug resistant pathogen shows a high biological cost for survival and that may also explain why, for some pathogens, the rate of resistant organisms is relatively low considering the widespread use of a particular drug. This seems the case of rifampicin resistant meningococci.
Insights
Rifampicin resistance in Neisseria meningitidis is rare, likely due to a biological cost. Differential protein expression in resistant strains affects metabolism and reduces invasion capacity, explaining their low prevalence.
Area of Science:
- Microbiology
- Proteomics
- Molecular Biology
Background:
- Rifampicin resistance mutations in Neisseria meningitidis are known, but the low prevalence of resistant strains remains unexplained.
- Investigating the proteomic differences between resistant and susceptible meningococci is crucial for understanding resistance mechanisms and strain rarity.
Purpose of the Study:
- To investigate the protein content and identify differentially expressed proteins in rifampicin-resistant Neisseria meningitidis compared to susceptible strains.
- To elucidate the potential impact of these protein expression changes on meningococcal fitness and virulence.
Main Methods:
- Two-dimensional electrophoresis (2-DE) was employed to separate and visualize proteins from resistant and susceptible meningococcal strains.
- Mass spectrometry was used in conjunction with 2-DE to identify differentially expressed proteins and analyze amino acid sequence changes.
Main Results:
- Twenty-three proteins showed differential expression in rifampicin-resistant strains compared to susceptible strains.
- Resistant strains exhibited increased expression of proteins involved in pyruvate catabolism and the tricarboxylic acid cycle, and decreased expression of proteins related to gene regulation and protein folding.
- Four proteins displayed altered isoelectric points in resistant strains, indicating amino acid sequence variations.
Conclusions:
- Differential protein expression in rifampicin-resistant Neisseria meningitidis suggests complex metabolic and regulatory changes.
- These proteomic alterations may contribute to a reduced invasion capacity and explain the low prevalence of resistant strains, supporting the concept of a biological cost associated with drug resistance.
