Using biophysical techniques to uncover a novel mechanism of immune evasion by Klebsiella pneumoniae KivA

Abstract

The bacterium Klebsiella pneumoniae, a leading cause of hospital-acquired infections, has gathered significant attention in recent years due to its escalating antibiotic resistance. This bacterium is being closely monitored, to prevent its morbidity and mortality from reaching an unbearable level, with an urgent need for new therapeutic treatments. During pathogenic invasion, the Interleukin 17 signalling pathway plays a crucial role in recruiting immune cells and other factors to effectively combat pathogens. K. pneumoniae has developed a strategy to suppress one of the key receptors in the IL-17 family, namely IL-17RA. The signalling of IL-17RA relies on SEFIR-SEFIR interactions between the SEFIR domain in IL-17RA and the adaptor protein Act1's SEFIR domain. By disrupting the SEFIR-SEFIR signalling through the self-generated SEFIR domain-containing protein called KivA, K. pneumoniae can evade the immune response initiated by IL-17RA. The objective of this thesis is to produce, biophysically characterise, and crystallise both KivA and the SEFIR domain of K. pneumoniae. While previous research on KivA has primarily focused on understanding its role in immune evasion by K. pneumoniae, this thesis aims to provide insights into the molecular properties of KivA. The results obtained from this thesis will be utilized in future studies investigating the interactions of KivA with its hypothesised binding partners, as well as in the production of crystals necessary for determining the 3D structure of KivA.