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Updated: May 2, 2026
Antimicrobial Peptides Produced by Selective Pressure Incorporation of Non-canonical Amino Acids
Published on: May 4, 2018
Small molecule inhibitors of Staphylococcus aureus RnpA alter cellular mRNA turnover, exhibit antimicrobial activity,
Patrick D Olson1, Lisa J Kuechenmeister, Kelsi L Anderson
1Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.
Abstract:
Methicillin-resistant Staphylococcus aureus is estimated to cause more U.S. deaths annually than HIV/AIDS. The emergence of hypervirulent and multidrug-resistant strains has further amplified public health concern and accentuated the need for new classes of antibiotics. RNA degradation is a required cellular process that could be exploited for novel antimicrobial drug development. However, such discovery efforts have been hindered because components of the Gram-positive RNA turnover machinery are incompletely defined. In the current study we found that the essential S. aureus protein, RnpA, catalyzes rRNA and mRNA digestion in vitro. Exploiting this activity, high through-put and secondary screening assays identified a small molecule inhibitor of RnpA-mediated in vitro RNA degradation. This agent was shown to limit cellular mRNA degradation and exhibited antimicrobial activity against predominant methicillin-resistant S. aureus (MRSA) lineages circulating throughout the U.S., vancomycin intermediate susceptible S. aureus (VISA), vancomycin resistant S. aureus (VRSA) and other Gram-positive bacterial pathogens with high RnpA amino acid conservation. We also found that this RnpA-inhibitor ameliorates disease in a systemic mouse infection model and has antimicrobial activity against biofilm-associated S. aureus. Taken together, these findings indicate that RnpA, either alone, as a component of the RNase P holoenzyme, and/or as a member of a more elaborate complex, may play a role in S. aureus RNA degradation and provide proof of principle for RNA catabolism-based antimicrobial therapy.
Insights
Researchers identified a novel small molecule inhibitor targeting the essential Staphylococcus aureus protein RnpA. This discovery offers a promising new strategy for developing antibiotics against drug-resistant bacteria like MRSA.
Area of Science:
- Microbiology
- Molecular Biology
- Drug Discovery
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant public health threat due to increasing drug resistance.
- Novel antibiotic classes are urgently needed to combat resistant bacterial strains.
- RNA degradation is a crucial cellular process with potential for antimicrobial drug development, but its machinery in Gram-positive bacteria is not fully understood.
Purpose of the Study:
- To investigate the role of Staphylococcus aureus protein RnpA in RNA degradation.
- To identify small molecule inhibitors of RnpA-mediated RNA degradation.
- To evaluate the antimicrobial potential of identified inhibitors against resistant bacterial strains.
Main Methods:
- In vitro assays to assess RnpA's catalytic activity on rRNA and mRNA.
- High-throughput and secondary screening to identify RnpA inhibitors.
- Testing antimicrobial activity against various S. aureus strains (MRSA, VISA, VRSA) and other Gram-positive pathogens.
- In vivo studies using a systemic mouse infection model and assessment of activity against biofilm-associated S. aureus.
Main Results:
- The essential S. aureus protein RnpA was found to catalyze rRNA and mRNA digestion in vitro.
- A small molecule inhibitor of RnpA-mediated RNA degradation was identified.
- The inhibitor demonstrated efficacy in limiting cellular mRNA degradation and exhibited antimicrobial activity against MRSA, VISA, VRSA, and other Gram-positive pathogens.
- The RnpA inhibitor ameliorated disease in a mouse model and showed activity against biofilm-associated S. aureus.
Conclusions:
- RnpA plays a role in S. aureus RNA degradation, potentially as part of RNase P or other complexes.
- The identified RnpA inhibitor provides proof of principle for RNA catabolism-based antimicrobial therapy.
- Targeting RnpA represents a promising novel strategy for developing new antibiotics against challenging Gram-positive bacterial infections.
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