Toxoplasma gondii Tic20 is essential for apicoplast protein import
Open Access
- 9 September 2008
- journal article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences of the United States of America
- Vol. 105 (36), 13574-13579
- https://doi.org/10.1073/pnas.0803862105
Abstract
Apicomplexan parasites harbor a secondary plastid that has lost the ability to photosynthesize yet is essential for the parasite to multiply and cause disease. Bioinformatic analyses predict that 5-10% of all proteins encoded in the parasite genome function within this organelle. However, the mechanisms and molecules that mediate import of such large numbers of cargo proteins across the four membranes surrounding the plastid remain elusive. In this work, we identify a highly diverged member of the Tic20 protein family in Apicomplexa. We demonstrate that Tic20 of Toxoplasma gondii is an integral protein of the innermost plastid membrane. We engineer a conditional null-mutant and show that TgTic20 is essential for parasite growth. To characterize this mutant functionally, we develop several independent biochemical import assays to reveal that loss of TgTic20 leads to severe impairment of apicoplast protein import followed by organelle loss and parasite death. TgTic20 is the first experimentally validated protein import factor identified in apicoplasts. Our studies provide experimental evidence for a common evolutionary origin of import mechanisms across the innermost membranes of primary and secondary plastids.Keywords
This publication has 26 references indexed in Scilit:
- A transient forward-targeting element for microneme-regulated secretion in Toxoplasma gondiiBiology of the Cell, 2008
- Evolution of malaria parasite plastid targeting sequencesProceedings of the National Academy of Sciences of the United States of America, 2008
- Apicoplast fatty acid synthesis is essential for organelle biogenesis and parasite survival inToxoplasma gondiiProceedings of the National Academy of Sciences of the United States of America, 2006
- Tic21 Is an Essential Translocon Component for Protein Translocation across the Chloroplast Inner Envelope MembranePlant Cell, 2006
- Toxoplasma gondii scavenges host-derived lipoic acid despite its de novo synthesis in the apicoplastThe EMBO Journal, 2006
- Monophyly of Primary Photosynthetic Eukaryotes: Green Plants, Red Algae, and GlaucophytesCurrent Biology, 2005
- High-Throughput Growth Assay forToxoplasma gondiiUsing Yellow Fluorescent ProteinAntimicrobial Agents and Chemotherapy, 2003
- Role of Toxoplasma gondii Myosin A in Powering Parasite Gliding and Host Cell InvasionScience, 2002
- In Vivo Analysis of the Role of atTic20 in Protein Import into ChloroplastsPlant Cell, 2002
- Expression, selection, and organellar targeting of the green fluorescent protein in Toxoplasma gondiiMolecular and Biochemical Parasitology, 1998