Preliminary crystallographic analysis of leishmania siamensis triosephosphate isomerase complexed with its novel inhibitor

Leishmania siamensis (Ls), a recently identified protozoan species that causes visceral leishmaniasis (VL), was isolated from a VL patient in Thailand. The putative gene encoding L. siamensis triosephosphate isomerase (LsTIM) was cloned and heterologously expressed as an N-terminal hexa-histidine-tag fusion protein in Escherichia coli. The purified recombinant LsTIM was found to fully function as a homodimeric enzyme, which could be crystallized and diffracted to the highest resolution of 1.93 Å using the rotating anode X-ray generator and 1.88 Å using the monochromatic X-ray from SLRI-beamline 7.2WLS at the Siam Photon Light Source. Chlorobiocin (NCI-227186), a novel inhibitor of LsTIM, was co-crystallized successfully with the enzyme by the microbatch method. The complex crystal diffracted synchrotron light at SLRI-beamline 7.2WLS to the resolution of 2.50 Å. Our preliminary crystallographic data presented in this study would help in elucidating the specific inhibitory binding sites of LsTIM that can be further designed as a drug target against VL.