title: The Plasmodium translocon of exported proteins (PTEX) component thioredoxin-2 is important for maintaining normal blood-stage growth.
abstract: Plasmodium parasites remodel their vertebrate host cells by translocating hundreds of proteins across an encasing membrane into the host cell cytosol via a putative export machinery termed PTEX. Previously PTEX150, HSP101 and EXP2 have been shown to be bona fide members of PTEX. Here we validate that PTEX88 and TRX2 are also genuine members of PTEX and provide evidence that expression of PTEX components are also expressed in early gametocytes, mosquito and liver stages, consistent with observations that protein export is not restricted to asexual stages. Although amenable to genetic tagging, HSP101, PTEX150, EXP2 and PTEX88 could not be genetically deleted in Plasmodium berghei, in keeping with the obligatory role this complex is postulated to have in maintaining normal blood-stage growth. In contrast, the putative thioredoxin-like protein TRX2 could be deleted, with knockout parasites displaying reduced grow-rates, both in vivo and in vitro, and reduced capacity to cause severe disease in a cerebral malaria model. Thus, while not essential for parasite survival, TRX2 may help to optimize PTEX activity. Importantly, the generation of TRX2 knockout parasites that display altered phenotypes provides a much-needed tool to dissect PTEX function.
authors.affiliation: School of Medicine, Deakin University, Waurn Ponds, Vic., 3216, Australia.
authors.forename: Kathryn
authors.initials: K
authors.lastname: Matthews
authors.forename: Ming
authors.initials: M
authors.lastname: Kalanon
authors.forename: Scott A
authors.initials: SA
authors.lastname: Chisholm
authors.forename: Angelika
authors.initials: A
authors.lastname: Sturm
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Goodman
authors.forename: Matthew W A
authors.initials: MW
authors.lastname: Dixon
authors.forename: Paul R
authors.initials: PR
authors.lastname: Sanders
authors.forename: Thomas
authors.initials: T
authors.lastname: Nebl
authors.forename: Fiona
authors.initials: F
authors.lastname: Fraser
authors.forename: Silvia
authors.initials: S
authors.lastname: Haase
authors.forename: Geoffrey I
authors.initials: GI
authors.lastname: McFadden
authors.forename: Paul R
authors.initials: PR
authors.lastname: Gilson
authors.forename: Brendan S
authors.initials: BS
authors.lastname: Crabb
authors.forename: Tania F
authors.initials: TF
authors.lastname: de Koning-Ward
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D017353:Gene Deletion; D016779:Malaria, Cerebral / Q000469:parasitology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018512:Parasitemia / Q000469:parasitology*; D010962:Plasmodium berghei / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D016019:Survival Analysis; D013879:Thioredoxins / Q000235:genetics / Q000378:metabolism*; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D037521:Virulence Factors; D013879:Thioredoxins