This Article Full Text Full Text (PDF) Supplemental material Alert me when this article is cited Alert me if a correction is posted Citation Map Services E-mail this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kalanon, M. Articles by McFadden, G. I. Search for Related Content PubMed PubMed Citation Articles by Kalanon, M. Articles by McFadden, G. I.

 Previous Article  |  Next Article 

Eukaryotic Cell, August 2009, p. 1146-1154, Vol. 8, No. 8
1535-9778/09/$08.00+0     doi:10.1128/EC.00061-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Characterization of Two Putative Protein Translocation Components in the Apicoplast of Plasmodium falciparum ^,

Ming Kalanon, Christopher J. Tonkin, and Geoffrey I. McFadden^*

School of Botany, University of Melbourne, Parkville, Victoria, Australia, 3010

Received 23 February 2009/ Accepted 1 June 2009

Protein trafficking to the stroma of the apicoplast of Plasmodium falciparum requires translocation across several membranes. To further elucidate the mechanisms responsible, we investigated two proteins: P. falciparum Tic22 (PfTic22), a putative component of the translocon of the inner chloroplast membrane; and PfsDer1-1, one of two homologues of the P. falciparum symbiont-derived Der1 (sDer1) protein, a putative component of an endoplasmic reticulum-associated degradation (ERAD) complex in the periplastid membrane. We constructed parasites expressing hemagglutinin (HA)-tagged PfTic22 and PfsDer1-1 under the control of their endogenous promoters using the 3' replacement strategy. We show that both PfTic22-HA and PfsDer1-1-HA are expressed predominantly during the trophozoite stage of the asexual replication cycle, which corresponds to the most dynamic stages of apicoplast activity. Although both proteins localize to the periphery of the apicoplast, PfTic22-HA is a membrane-associated protein while PfsDer1-1-HA is an integral membrane protein. Phylogenetic analysis indicates that PfsDer1-1 is one of two Der1 paralogues predicted to localize to the apicoplast in P. falciparum and that it has orthologues in diatom algae, supporting the chromalveolate hypothesis. These observations are consistent with putative roles for PfTic22 and PfsDer1-1 in protein translocation into the apicoplast of P. falciparum.

---

* Corresponding author. Mailing address: School of Botany, University of Melbourne, Parkville, Victoria, Australia 3010. Phone: 61 3 8344 5053. Fax: 61 3 9347 5460. E-mail: gim{at}unimelb.edu.au

Published ahead of print on 5 June 2009.

Supplemental material for this article may be found at http://ec.asm.org/.

Present address: Division of Infection and Immunity, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia 3050.

---

Eukaryotic Cell, August 2009, p. 1146-1154, Vol. 8, No. 8
1535-9778/09/$08.00+0     doi:10.1128/EC.00061-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

This article has been cited by other articles:

• Keeling, P. J. (2010). The endosymbiotic origin, diversification and fate of plastids. Phil Trans R Soc B 365: 729-748 [Abstract] [Full Text]  
• Lim, L., McFadden, G. I. (2010). The evolution, metabolism and functions of the apicoplast. Phil Trans R Soc B 365: 749-763 [Abstract] [Full Text]  
• Agrawal, S., van Dooren, G. G., Beatty, W. L., Striepen, B. (2009). Genetic Evidence that an Endosymbiont-derived Endoplasmic Reticulum-associated Protein Degradation (ERAD) System Functions in Import of Apicoplast Proteins. J. Biol. Chem. 284: 33683-33691 [Abstract] [Full Text]