Abstract
A model for parasitic motility has been proposed in which parasite filamentous actin (F-actin) is attached to surface adhesins by a large component of the glideosome, known as the glideosome-associated connector protein (GAC). This large 286 kDa protein interacts at the cytoplasmic face of the plasma membrane with the phosphatidic acid-enriched inner leaflet and cytosolic tails of surface adhesins to connect them to the parasite actomyosin system. GAC is observed initially to the conoid at the apical pole and re-localised with the glideosome to the basal pole in gliding parasite. GAC presumably functions in force transmission to surface adhesins in the plasma membrane and not in force generation. Proper connection between F-actin and the adhesins is as important for motility and invasion as motor operation itself. This notion highlights the need for new structural information on GAC interactions, which has eluded the field since its discovery. We have obtained crystals that diffracted to 2.6–2.9 Å for full-length GAC from Toxoplasma gondii in native and selenomethionine-labelled forms. These crystals belong to space group P212121; cell dimensions are roughly a = 119 Å, b = 123 Å, c = 221 Å, α = 90°, β = 90° and γ = 90° with 1 molecule per asymmetric unit, suggesting a more compact conformation than previously proposed
Highlights
There are more than 5000 species of apicomplexan parasites and many are etiological agents of major diseases that are a threat to global human and animal health, in low-resource settings [1]
Most significant are malaria (Plasmodium), cryptosporidiosis (Cryptosporidium) and toxoplasmosis (Toxoplasma). The lifestyle of these obligate intracellular parasites involves crucial steps that depend on gliding motility such as host cell invasion, egress from infected cell and crossing of biological barriers [2]
Thethe molecular component thatconnector bridges the adhesin to filamentous actin (F-actin) a large novelwith protein termed glideosome associated protein (GAC), whichis translocates the termed the glideosome associated connector protein (GAC), which translocates with the moving junction from the parasite apex to the basal pole during gliding motility [8]
Summary
There are more than 5000 species of apicomplexan parasites and many are etiological agents of major diseases that are a threat to global human and animal health, in low-resource settings [1]. Most significant are malaria (Plasmodium), cryptosporidiosis (Cryptosporidium) and toxoplasmosis (Toxoplasma) The lifestyle of these obligate intracellular parasites involves crucial steps that depend on gliding motility such as host cell invasion, egress from infected cell and crossing of biological barriers [2]. Thethe molecular component thatconnector bridges the adhesin to F-actin a large novelwith protein termed glideosome associated protein (GAC), whichis translocates the termed the glideosome associated connector protein (GAC), which translocates with the moving junction from the parasite apex to the basal pole during gliding motility [8]. With secondary structure and of the purification conditions together with secondary structure analyses and extensive extensive crystallization screening, we generated high quality crystals that diffract to 2.67 crystallization screening, we generated high quality crystals that diffract to 2.67 Å resolution This represents a key breakthrough in providing the first structural insight into the GAC architecture and function within the glideosome
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