Structural dynamics of <i>Rhipicephalus microplus</i> serpin-3

Cattle ticks, Rhipicephalus (Boophilus) microplus, have a serious impact on livestock worldwide. For tick control, host vaccination is more sustainable than chemical. Salivary serpin (serine protease inhibitor) from R. microplus (RmS-3) potential anti-tick vaccine candidate antigen. Like other serpins, RmS-3 has suicide inhibition mechanism, where the reactive centre loop (RCL) cleaved and then inserted into main β-pleated sheet. This causes breakdown of two regions (core domain polypeptide). A small sequence variation was observed among specimens in Thailand included three extra amino acids (T147, K180, N193). Molecular Dynamics simulations previously reported (Micro) novel Thai (Thai) were conducted comparison. Overall, Micro rigid Thai. Having additional T147 K180 enhance structural flexibility Both residues are located close to areas that perform distinct conformational change, so may inhibitory activity RmS-3. In contrast, N193 seems minor effect. presence cause significant differences dynamics which lead different degrees activity. Further experimental studies required.