| Abstract [eng] |
Klebsiella spp. bacteria pose a significant threat to human health, particularly in individuals with compromised immune systems. Therefore, effective strategies to combat this pathogen must be developed. Klebsiella genus bacteria are known to exhibit multi-antibiotic resistance and are difficult to eradicate due to their virulence factors. However, bacteriophages may offer hope to affected patients, as their inherent nature is to "reproduce" and "kill" by exploiting bacterial vitality. The RaK2 virus is one of many bacteriophages capable of lysing Klebsiella pneumoniae. However, its uniqueness lies in its genome size – as it is classified as a jumbo phage belonging to the Alcyoneusvirus genus – and in the distinctive morphology of its adsorption complex. Notably, viruses within this genus remain largely understudied, particularly regarding the structure and function of their adsorption complexes. Therefore, the primary aim of this dissertation was to investigate the branched long tail fibres located within the adsorption complex of the RaK2 phage. The study encompassed a variety of experiments focused on the proteins that comprise the fibre, including the determination of their location, structure, and function. Specifically, structural modelling, phage adsorption inhibition assays, immuno-labelling, and enzymatic specificity analyses were utilised. As a result, a probable architecture of the RaK2 branched long tail fibre was proposed, and key proteins involved in initiating phage infection – gp531 and gp098 – were identified. Furthermore, the enzymatic specificity of the associated depolymerase gp531 was determined to be beta-(1,4)-glucosidase, which targets and degrades the capsular polysaccharide of K. pneumoniae K54 serotype. |
