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Molecular basis of bacterial electrophysiology

Principal Supervisor: Dr Munehiro AsallyLink opens in a new window

Co-supervisor: Prof Nick Dale

PhD project title: Molecular basis of bacterial electrophysiology

University of Registration: University of Warwick


Project outline:

Many bacteria carry genes that encode ion channels 1. The structure of the bacterial ion channels are remarkably similar to the neural ion channels in neurons. By this reason, the bacterial ion channels have been used as the model system for studying the molecular basis of neural electrical signalling. The primal example is the structural study of KscA potassium channel, which led Dr R MacKinnon to receive the Novel prize 2. While bacterial ion channels have been serving as high-quality models for neural investigation, the physiological roles of these ion channels in bacteria are still largely unexplored. For example, in 2002, Iyer et al wrote “prokaryotes use ion channels in roles more adaptive than providing high-quality protein to structural biologists3. However, the physiological roles of ion channels have received limited attention by microbiologists.

Recent studies, including ours, have shown that bacterial ion channels can mediate electrical signalling bacterial biofilms 4,5. Bacterial electrical signalling allow coordination of resource allocation in biofilms, mechanosensation and quality control during spore formation 5,6. While the bacterial electrical signalling propagates much more slowly than neural signalling, there are also similarities between bacterial electrical signalling and neural signalling.

Besides electrical signalling in biofilms, bacterial membrane potential has been shown to relate to antibiotic tolerance 7. Therefore, understanding the molecular basis of membrane potential regulation is an important research question with broad potential applications in biological and biomedical research.

This topic is in a good synergy with recent development in other domains of biology where electrical signalling has been shown to take place in plants and tumours. Investigation of bioelectrical signalling is a timely research topic.

This project aims to systematically analyse all putative ion channels in the Gram-positive model bacterium Bacillus subtilis. Two main objectives of the project are:

Objective 1. Electrophysiological characterisation of putative ion channel

Objective 2. Characterisation of Cl- dynamics in bacterial electrical signalling

For Objective 1, putative ion channels have been already listed by a machine-learning tool to predict ion channels, PSIONplus 8. To carry on patch clamp assays, the ion channel proteins will be expressed in HeLa cells. The conductivity of each protein will be quantitatively characterised by patch clamp. This will be the first systematic analysis of bacterial ion channels. For Objective 2, fluorescent reporter protein for chloride will be established in Bacillus subtilis.

Keywords: bioelectricity, bioelectrical engineering, bacterial electrophysiology, microbiology, biophysics, physics of life

References:

  1. Delcour, A. H. Electrophysiology of Bacteria. Annu. Rev. Microbiol. 67, 179–197 (2013).
  2. MacKinnon, R. Potassium Channels and the Atomic Basis of Selective Ion Conduction (Nobel Lecture). Angew. Chemie Int. Ed. 43, 4265–4277 (2004).
  3. Iyer, R., Iverson, T. M., Accardi, A. & Miller, C. A biological role for prokaryotic CIC chloride channels. Nature 419, 715–718 (2002).
  4. Prindle, A. et al. Ion channels enable electrical communication in bacterial communities. Nature 527, 59–63 (2015).
  5. Benarroch, J. M. J. M. J. M. & Asally, M. The Microbiologist’s Guide to Membrane Potential Dynamics. Trends Microbiol. 28, 304–314 (2020).
  6. Galera-Laporta, L., Comerci, C. J., Garcia-Ojalvo, J. & Süel, G. M. IonoBiology: The functional dynamics of the intracellular metallome, with lessons from bacteria. Cell Syst. 12, 497–508 (2021).
  7. Bruni, G. N. & Kralj, J. M. Membrane voltage dysregulation driven by metabolic dysfunction underlies bactericidal activity of aminoglycosides. Elife 9, 1–25 (2020).
  8. Gao, J., Cui, W., Sheng, Y., Ruan, J. & Kurgan, L. PSIONplus: Accurate sequence-based predictor of ion channels and their types. PLoS One 11, 1–18 (2016)

 

BBSRC Strategic Research Priority: Understanding the rules of life Microbiology

 

Techniques that will be undertaken during the project:

- Molecular cloning

- Time-lapse Fluorescence microscopy

- Patch clamp

- Quantitative image analysis

- Plate reader assays

 

Contact: Dr Munehiro AsallyLink opens in a new window