Surface attachment, promoted by the actomyosin system of Toxoplasma gondii is important for efficient gliding motility and invasion

BMC Biology

Research Article

Jacqueline M. Leung¹  Gary E. Ward²  Shane R. Nelson³  Aoife Heaslip³  David M. Warshaw³  Nicole Andenmatten⁴  Gurman S. Pall⁴  Saskia Egarter⁴  Jamie A. Whitelaw⁴  Simon Gras⁴  Markus Meissner⁴  Fernanda Latorre-Barragan⁴ 

[1] Department of Biology, Indiana University, Bloomington, Myers Hall 240, 915 E 3rd St Bloomington, 47405, Bloomington, IN, USA;University of Vermont, Department of Microbiology and Molecular Genetics, College of Medicine, 05405, Burlington, VT, USA;University of Vermont, Department of Microbiology and Molecular Genetics, College of Medicine, 05405, Burlington, VT, USA;University of Vermont, Department of Molecular Physiology and Biophysics Burlington, 05405, Vermont, USA;Wellcome Trust Centre For Molecular Parasitology, Institute of Infection, Immunity & Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, G12 8TA, Glasgow, UK;

关键词: Actin;    Myosin;    Motility;    Attachment;    Toxoplasma;    Apicomplexa;    Host cell invasion;    Membrane flow;   

DOI  :  10.1186/s12915-016-0343-5

 received in 2016-09-17, accepted in 2016-12-10,  发布年份 2017

来源: Springer

【 摘 要 】

BackgroundApicomplexan parasites employ a unique form of movement, termed gliding motility, in order to invade the host cell. This movement depends on the parasite’s actomyosin system, which is thought to generate the force during gliding. However, recent evidence questions the exact molecular role of this system, since mutants for core components of the gliding machinery, such as parasite actin or subunits of the MyoA-motor complex (the glideosome), remain motile and invasive, albeit at significantly reduced efficiencies. While compensatory mechanisms and unusual polymerisation kinetics of parasite actin have been evoked to explain these findings, the actomyosin system could also play a role distinct from force production during parasite movement.ResultsIn this study, we compared the phenotypes of different mutants for core components of the actomyosin system in Toxoplasma gondii to decipher their exact role during gliding motility and invasion. We found that, while some phenotypes (apicoplast segregation, host cell egress, dense granule motility) appeared early after induction of the act1 knockout and went to completion, a small percentage of the parasites remained capable of motility and invasion well past the point at which actin levels were undetectable. Those act1 conditional knockout (cKO) and mlc1 cKO that continue to move in 3D do so at speeds similar to wildtype parasites. However, these mutants are virtually unable to attach to a collagen-coated substrate under flow conditions, indicating an important role for the actomyosin system of T. gondii in the formation of attachment sites.ConclusionWe demonstrate that parasite actin is essential during the lytic cycle and cannot be compensated by other molecules. Our data suggest a conventional polymerisation mechanism in vivo that depends on a critical concentration of G-actin. Importantly, we demonstrate that the actomyosin system of the parasite functions in attachment to the surface substrate, and not necessarily as force generator.

【 授权许可】

CC BY   
© The Author(s). 2017