MyD88 adaptor protein (MAL) / TIR domain-containing adaptor protein (TIRAP) is a key player in the Toll-like receptor (TLR) signalling cascade of the human immune system. As the TLRs are stimulated, the Toll/ interleukin-1 receptor (TIR) domain of MAL binds to the intracellular domain of the TLR to relay the signal to MyD88 and in turn activate the production of NF-kB and cytokines.
Our group recently solved the crystal structure of MAL, which showed that specific cysteines formed two disulphide bonds that could contribute to the stability of the protein. However, it has been hypothesised that those cysteines may in fact participate in redox-mediated conformational change of the protein. In addition, another pair of cysteines that are in close proximity to each other, while not forming a disulfide bond, may be involved in binding and signal transduction.
Based on these observations, the sample conditions were optimised for NMR and the backbone assigned to give insight into the redox state of the cysteine residues in solution. Future work will be focused on the functional role of cysteines in the MAL protein.