concerted action of two formins in gliding motility and host cell invasion by toxoplasma gondii采取协调一致的行动滑翔二甲酸精的能动性和刚地弓形虫入侵宿主细胞.pdfVIP

Concerted Action of Two Formins in Gliding Motility and Host Cell Invasion by Toxoplasma gondii 1 1 2 1 Wassim Daher , Fabienne Plattner , Marie-France Carlier , Dominique Soldati-Favre * 1 Department of Microbiology and Molecular Medicine, CMU, University of Geneva, Geneva, Switzerland, 2 Dynamique du Cytosquelette, Laboratoire d’Enzymologie et Biochimie Structurales UPR A 9063, CNRS, Gif sur Yvette, France Abstract The invasive forms of apicomplexan parasites share a conserved form of gliding motility that powers parasite migration across biological barriers, host cell invasion and egress from infected cells. Previous studies have established that the duration and direction of gliding motility are determined by actin polymerization; however, regulators of actin dynamics in apicomplexans remain poorly characterized. In the absence of a complete ARP2/3 complex, the formin homology 2 domain containing proteins and the accessory protein profilin are presumed to orchestrate actin polymerization during host cell invasion. Here, we have undertaken the biochemical and functional characterization of two Toxoplasma gondii formins and established that they act in concert as actin nucleators during invasion. The importance of TgFRM1 for parasite motility has been assessed by conditional gene disruption. The contribution of each formin individually and jointly was revealed by an approach based upon the expression of dominant mutants with modified FH2 domains impaired in actin binding but still able to dimerize with their respective endogenous formin. These mutated FH2 domains were fused to the ligand-controlled destabilization domain (DD-FKBP) to achieve conditional expression. This strategy proved unique in identifying the non- redundant and crit