title: Apicoplast fatty acid synthesis is essential for pellicle formation at the end of cytokinesis in Toxoplasma gondii.
abstract: The apicomplexan protozoan Toxoplasma gondii, the causative agent of toxoplasmosis, harbors an apicoplast, a plastid-like organelle with essential metabolic functions. Although the FASII fatty acid biosynthesis pathway located in the apicoplast is essential for parasite survival, the cellular effects of FASII disruption in T. gondii had not been examined in detail. Here, we combined light and electron microscopy techniques - including focused ion beam scanning electron microscopy (FIB-SEM) - to characterize the effect of FASII disruption in T. gondii, by treatment with the FASII inhibitor triclosan or by inducible knockdown of the FASII component acyl carrier protein. Morphological analyses showed that FASII disruption prevented cytokinesis completion in T. gondii tachyzoites, leading to the formation of large masses of 'tethered' daughter cells. FIB-SEM showed that tethered daughters had a mature basal complex, but a defect in new membrane addition between daughters resulted in incomplete pellicle formation. Addition of exogenous fatty acids to medium suppressed the formation of tethered daughter cells and supports the notion that FASII is essential to generate lipid substrates required for the final step of parasite division.
authors.affiliation: Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil, 21.941-902 Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens, Rio de Janeiro, Brazil, 21.941-902 erica@biof.ufrj.br wsouza@biof.ufrj.br.
authors.forename: Érica S
authors.identifier: 0000-0003-0925-6953
authors.initials: ÉS
authors.lastname: Martins-Duarte
authors.affiliation: Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil, 21.941-902 Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens, Rio de Janeiro, Brazil, 21.941-902.
authors.forename: Maira
authors.initials: M
authors.lastname: Carias
authors.affiliation: Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil, 21.941-902 Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens, Rio de Janeiro, Brazil, 21.941-902.
authors.forename: Rossiane
authors.initials: R
authors.lastname: Vommaro
authors.affiliation: Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, India, 560064.
authors.forename: Namita
authors.initials: N
authors.lastname: Surolia
authors.affiliation: Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil, 21.941-902 Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens, Rio de Janeiro, Brazil, 21.941-902 erica@biof.ufrj.br wsouza@biof.ufrj.br.
authors.forename: Wanderley
authors.initials: W
authors.lastname: de Souza
mesh_terms: D000818:Animals; D063546:Apicoplasts / Q000378:metabolism* / Q000648:ultrastructure; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D048749:Cytokinesis; D064429:Fatty Acid Synthases / Q000378:metabolism; D005227:Fatty Acids / Q000096:biosynthesis*; D055785:Gene Knockdown Techniques; D008018:Life Cycle Stages / Q000187:drug effects; D008253:Macaca mulatta; D010271:Parasites / Q000166:cytology / Q000187:drug effects / Q000254:growth & development / Q000648:ultrastructure; D014122:Toxoplasma / Q000166:cytology* / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure; D014260:Triclosan / Q000494:pharmacology
chemical_list: D005227:Fatty Acids; D014260:Triclosan; D064429:Fatty Acid Synthases
keywords: Apicomplexa; Bradyzoite; Cell division; Cleavage furrow; Triclosan