Plasmodium myosin A drives parasite invasion by an atypical force generating mechanism

Abstract

Plasmodium parasites are obligate intracellular protozoa and causative agents of malaria, responsible for half a million deaths each year. The lifecycle progression of the parasite is reliant on cell motility, a process driven by myosin A, an unconventional single-headed class XIV molecular motor. Here we demonstrate that myosin A from Plasmodium falciparum (PfMyoA) is critical for red blood cell invasion. Further, using a combination of X-ray crystallography, kinetics, and in vitro motility assays, we elucidate the non-canonical interactions that drive this motor’s function. We show that PfMyoA motor properties are tuned by heavy chain phosphorylation (Ser19), with unphosphorylated PfMyoA exhibiting enhanced ensemble force generation at the expense of speed. Regulated phosphorylation may therefore optimize PfMyoA for enhanced force generation during parasite invasion or for fast motility during dissemination. The three PfMyoA crystallographic structures presented here provide a blueprint for discovery of specific inhibitors designed to prevent parasite infection.

Structural role of essential light chains in the apicomplexan glideosome

“…Crystal structures of T. gondii and P. falciparum MyoA [23, 24] as well as structures of their distal light chains MLC1 (MTIP) [15, 22] have already been determined. To shed light on the architecture and folding of the recently identified proximal essential light chains (ELCs) we studied their structure in the context of their interaction partners.…”

“…However, both TgMyoA-C as well as PfMyoA-C are unfolded or partially unfolded in isolation (S3C Fig). Indeed, the C-terminal amino acid residues of the recently published TgMyoA [23] and PfMyoA [24] motor domain structures could not be resolved, likely due to their intrinsically disordered nature. We hypothesized that the essential light chains can induce α-helical structure in MyoA upon binding, therefore we measured circular dichroism of TgMyoA-C ELC and TgELC2 in isolation and in the complex (Fig 4D).…”

“…Structural information on individual members and subcomplexes of the glideosome are limited and the architecture of the entire glideosome is elusive. So far, only the structures of P. falciparum PfGAP50 soluble domain [21], a T. gondii dimeric complex between the TgMyoA C-terminus and MLC1 [15], a homologous dimeric complex in P. falciparum between PfMyoA C-terminus and MTIP [22], and the motor domains of the T. gondii TgMyoA [23] and P. falciparum PfMyoA [24] are available (S1 Table).…”

Phosphorylation-Dependent Assembly of a 14-3-3 Mediated Signaling Complex During Red Blood Cell Invasion byPlasmodium falciparumMerozoites

“…Various myosin molecules, PfMyoA, PfMyoB and PfMyoE, as well as glideosome-associated proteins, PfGAP40 and PfGAP45, were phosphorylated. It has been proposed recently that regulated phosphorylation of S19 in PfMyoA may enhance force generation during parasite invasion (18).…”

Conformational distributions of isolated myosin motor domains encode their mechanochemical properties

“…Myosin-Va and Vb from all organisms were assumed to have high duty ratios and Myosin-Vc was assumed to have a low duty ratio. Plasmodium falciparum MyoA (6I7D) has been shown to have a high duty ratio (Robert-Paganin et al, 2019).…”