Abstract
Antimicrobial tolerance is the ability of a microbial population to survive, but not proliferate, during antimicrobial exposure. Significantly, it has been shown to precede the development of bona fide antimicrobial resistance. We have previously identified the two-component system CroRS as a critical regulator of tolerance to antimicrobials like teixobactin in the bacterial pathogen Enterococcus faecalis. To understand the molecular mechanism of this tolerance, we have carried out RNA-seq analyses in the E. faecalis wild-type and isogenic (Figure presented.) croRS mutant to determine the teixobactin-induced CroRS regulon. We identified a 132 gene CroRS regulon and demonstrate that CroRS upregulates biosynthesis of all major components of the enterococcal cell envelope in response to teixobactin. This suggests a coordinating role of this regulatory system in maintaining integrity of the multiple layers of the enterococcal envelope during antimicrobial stress, likely contributing to bacterial survival. Using experimental evolution, we observed that truncation of HppS, a key enzyme in the synthesis of the quinone electron carrier demethylmenaquinone, was sufficient to rescue tolerance in the croRS deletion strain. This highlights a key role for isoprenoid biosynthesis in antimicrobial tolerance in E. faecalis. Here, we propose a model of CroRS acting as a master regulator of cell envelope biogenesis and a gate-keeper between isoprenoid biosynthesis and respiration to ensure tolerance against antimicrobial challenge.
| Original language | English |
|---|---|
| Pages (from-to) | 408-424 |
| Number of pages | 17 |
| Journal | Molecular Microbiology |
| Volume | 120 |
| Issue number | 3 |
| Early online date | 20 Jul 2023 |
| DOIs | |
| Publication status | Published - Sept 2023 |
Bibliographical note
Funding Information:All authors acknowledge funding support from the Health Research Council (HRC) (NZ) 20/213, the Maurice Wilkins Centre for Molecular Biodiscovery (NZ) and the University of Otago Research Grant (NZ). F. O. Todd Rose was supported by a University of Otago PhD Scholarship (NZ), and S. Morris was supported by a GW4 BioMed Medical Research Council (MRC) Doctoral Training Partnership Scholarship (UK). The authors thank Dallas Hughes from Novobiotic for the kind gift of teixobactin. The authors thank the Otago Genomics Facility for carrying out library preparation and RNA sequencing of the RNA samples. The authors also thank Fatima Esperanca Jorge and Richard Easingwood at the Otago Micro and Nano Imaging Unit, University of Otago for their assistance in the preparation and collection of the transmission electron microscopy images. The authors thank Chris Vennard at the University of Bath facility for custom raising of the caterpillars, technical support and expert advice for their handling. Figures 2 and 6 were generated using BioRender with publishing permissions. Open access publishing facilitated by University of Otago, as part of the Wiley ‐ University of Otago agreement via the Council of Australian University Librarians. Manduca sexta
Funding
All authors acknowledge funding support from the Health Research Council (HRC) (NZ) 20/213, the Maurice Wilkins Centre for Molecular Biodiscovery (NZ) and the University of Otago Research Grant (NZ). F. O. Todd Rose was supported by a University of Otago PhD Scholarship (NZ), and S. Morris was supported by a GW4 BioMed Medical Research Council (MRC) Doctoral Training Partnership Scholarship (UK). The authors thank Dallas Hughes from Novobiotic for the kind gift of teixobactin. The authors thank the Otago Genomics Facility for carrying out library preparation and RNA sequencing of the RNA samples. The authors also thank Fatima Esperanca Jorge and Richard Easingwood at the Otago Micro and Nano Imaging Unit, University of Otago for their assistance in the preparation and collection of the transmission electron microscopy images. The authors thank Chris Vennard at the University of Bath facility for custom raising of the caterpillars, technical support and expert advice for their handling. Figures 2 and 6 were generated using BioRender with publishing permissions. Open access publishing facilitated by University of Otago, as part of the Wiley ‐ University of Otago agreement via the Council of Australian University Librarians. Manduca sexta All authors acknowledge funding support from the Health Research Council (HRC) (NZ) 20/213, the Maurice Wilkins Centre for Molecular Biodiscovery (NZ) and the University of Otago Research Grant (NZ). F. O. Todd Rose was supported by a University of Otago PhD Scholarship (NZ), and S. Morris was supported by a GW4 BioMed Medical Research Council (MRC) Doctoral Training Partnership Scholarship (UK). The authors thank Dallas Hughes from Novobiotic for the kind gift of teixobactin. The authors thank the Otago Genomics Facility for carrying out library preparation and RNA sequencing of the RNA samples. The authors also thank Fatima Esperanca Jorge and Richard Easingwood at the Otago Micro and Nano Imaging Unit, University of Otago for their assistance in the preparation and collection of the transmission electron microscopy images. The authors thank Chris Vennard at the University of Bath Manduca sexta facility for custom raising of the caterpillars, technical support and expert advice for their handling. Figures 2 and 6 were generated using BioRender with publishing permissions. Open access publishing facilitated by University of Otago, as part of the Wiley - University of Otago agreement via the Council of Australian University Librarians.
| Funders | Funder number |
|---|---|
| Australian University Librarians | |
| GW4 BioMed Medical Research Council | |
| Otago Genomics Facility | |
| University of Otago | |
| Medical Research Council | |
| Health Research Council of New Zealand | 20/213 |
| Maurice Wilkins Centre for Molecular Biodiscovery |
Keywords
- bacterial
- cell wall
- drug resistance
- Enterococcus faecalis
- isoprenoids
- regulation
- RNA-seq
- tolerance
ASJC Scopus subject areas
- Microbiology
- Molecular Biology