Our objective is to understand the structural relationship between TLR5 human homolog, TLR11 mouse homolog and their respective ligands. The human TLR5 recognizes flagellin whereas TLR11 recognizes a structural protein profilin. The biochemical aspects of these interactions are well understood. An initial attempt in expressing hTLR5 and mTLR11 ecto domains by themselves in a baculovirus system was unsuccessful. The proteins were either degraded overtime or driven into inclusion bodies. Even under these conditions, small quantities of TLR5 were isolated from the cell pellet as a soluble protein. The extracted hTLR5 protein has shown to be glycosylated and the N-terminal signal peptide has been processed. However, the insect cellular system is unable to export the protein. Since then we have been able to overexpress the secreted TLR5 as a fusion protein in the insect cell system. Similarly, mTRL11 fusion protein was also able to express in large quantities. Currently we are in the process of troubleshooting the purification issues that are related to the fusion proteins. This method has enabled us to express the both the TLR fusion proteins, TLR5 and TLR11, in significant quantities.
