Characterization of the dual functions of Leishmania CK1.2 in both the parasite and the macrophage.

Leishmania CK1.2 (L-CK1.2) is a serine/threonine protein kinase essential for the survival of the protozoan parasite Leishmania, the causative agent of leishmaniasis. This study investigates the dynamic localization pattern of L-CK1.2 and the broad spectrum of its interacting partners within the parasite. Using proteomic analysis and confocal microscopy, we identified 230 L-CK1.2-associated proteins across the major parasite life stages. This analysis revealed the ubiquitous presence of L-CK1.2 in various cellular structures, including the cytoskeleton, basal body, and flagellum. Using an in vitro system, sixty-four host proteins, involved in critical host biological processes such as immune response, apoptosis, and purine biosynthesis, were identified as potential interacting partners of L-CK1.2. These processes are known to be regulated by Leishmania during infection. The study highlights the potential dual function of L-CK1.2, in the parasite (cis) and within the host cell (trans), positioning this kinase as a key player in host-pathogen interactions. This work provides a comprehensive map of L-CK1.2 interactions and suggests its potential importance in regulating intracellular Leishmania survival, providing potential targets for leishmaniasis therapy. Furthermore, given the evolutionary conservation of CK1.2 across other parasitic organisms, our findings may have broader implications for understanding and managing parasitic infections.