An atlas of novel microtubule-associated proteins in the malaria parasite <i>Plasmodium falciparum</i>

Mature gametocytes of <i>Plasmodium falciparum</i> exhibit a characteristic falciform shape, which is conferred by a complex array of subpellicular microtubules (SPMTs) associated with the inner membrane complex (IMC). While several microtubule-associated proteins (MAPs) have been characterized in the related apicomplexan parasite <i>Toxoplasma gondii</i>, the identity and function of MAPs in <i>Plasmodium</i> remain poorly understood. Here, we employed proximity-dependent biotinylation (BioID) using <i>Pf</i>SPM3, a subpellicular MAP, as a bait in order to identify proteins associated with <i>P. falciparum</i> gametocyte SPMTs. Mass spectrometry analysis revealed 37 high-confidence proteins in the immediate vicinity of <i>Pf</i>SPM3 constituting its "proxiome." Using GFP tags on the endogenous proteins of 11 highly enriched candidates, we provide a spatial localization atlas of previously uncharacterized proteins. Notably, many of these putative MAPs showed a distinct localization to different structures within the SPMT network, highlighting its complexity in developing gametocytes. Among these, we demonstrate that functional knockout of one MAP, PF3D7_1003400, which exhibits a localization pattern consistent with positioning near the IMC suture/SPMT boundary, interferes with gametocytogenesis and prevents falciform gametocyte development. These findings provide the first atlas of the SPMT network required to coordinate cytoskeletal dynamics, IMC organization, and gametocyte development. Understanding these interactions offers new avenues for blocking gametocyte cytoskeleton development and malaria transmission.IMPORTANCETransmission of <i>Plasmodium falciparum</i> relies on the formation of falciform gametocytes, a process dependent on the dynamic interplay between subpellicular microtubules (SPMTs) and the inner membrane complex (IMC). In this study, we employed proximity-dependent biotinylation using <i>Pf</i>SPM3, an SPMT-associated protein, as a bait. We present a comprehensive list of highly enriched proteins and a validation of the top candidates revealing novel components of the cytoskeleton of gametocytes that might play a role in their morphogenesis and transmission.