Structural characterisation of a phage-like bacteriocin from Pseudomonas sp. by cryo-Electron Microscopy

DOI: 10.1051/bioconf/202412921010

Authors: Eilis Bragginton (Diamond Light Source) , Miles Graham (Diamond Light Source; University of Oxford) , Liam Mead (Diamond Light Source) , Matthew Byrne (Diamond Light Source) , Karen Davies (Diamond Light Source)
Co-authored by industrial partner: No

Type: Conference Paper
Conference: The 17th European Microscopy Congress (EMC 2024)
Peer Reviewed: No

State: Published (Approved)
Published: October 2024

Abstract: Background incl. aims: Antibiotic resistance is a global health crisis with the ever growing need to develop novel antibiotics and strategies to treat resistant infections. Bacteriophage therapy is often highlighted as an alternative approach due to its high specificity to kill a certain bacterial strain. However, bacteriophage propagate through a replication cycle within the target bacterium, with the potential to generate mutations with detrimental consequences. Strains of Pseudomonas sp. produce phage tail-like bacteriocins (PTLBs) which have evolved from bacteriophage. Although sharing many similarities, they differ from bacteriophage lacking a capsid and therefore the ability to replicate. These unique features highlight the potential of PTLBs as an alternative therapy to treat bacterial infections as they can be tittered to a specific dose. However, for PTLBs to be implemented as a bactericidal treatment, further information is needed regarding their structure, mechanism of action and how they recognise their target strains. We have isolated a contracting PTLB from an environmental strain of P. veronii and determined its structure by cryo-EM. Methods: The PTLB was purified by ammonium sulphate precipitation and visualised by cryo-EM. The structure of the PTLB was determined using a combination approach of single particle and helical analysis. Results: The structure was determined of a new clade of contracting PTLBs in both its uncontracted and contracted states. We also identified the lack of a ‘ruler protein’ for the purified PTLBs, observing varying lengths in the collected micrographs. Conclusion: We solved the structure of a novel contracting PTLB and show that it shares structural similarities with the previously characterised contractile nanomachine from P. aeruginosa. We also observe that inconsistent lengths of PTLBs does not appear to affect the lethality of the PTLB to its target strain.

Journal Keywords: Bacteriocin; filament; cryo-EM

Diamond Keywords: Bacteria

Subject Areas: Biology and Bio-materials, Chemistry

Diamond Offline Facilities: Electron Bio-Imaging Centre (eBIC)
Instruments: Krios I-Titan Krios I at Diamond

Added On: 24/10/2024 10:40

Documents:
bioconf_emc2024_21010.pdf

Discipline Tags:

Pathogens Antibiotic Resistance Infectious Diseases Health & Wellbeing Biochemistry Chemistry Structural biology Life Sciences & Biotech

Technical Tags:

Microscopy Electron Microscopy (EM) Cryo Electron Microscopy (Cryo EM)