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Eukaryotic Cell, September 2009, p. 1330-1340, Vol. 8, No. 9
1535-9778/09/$08.00+0     doi:10.1128/EC.00092-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

The Longin Domain Regulates the Steady-State Dynamics of Sec22 in Plasmodium falciparum{triangledown}

Lawrence Ayong,1 Avanthi Raghavan,1 Timothy G. Schneider,3 Theodore F. Taraschi,3 David A. Fidock,2 and Debopam Chakrabarti1*

Department of Molecular Biology and Microbiology, Burnett School of Biomedical Sciences, University of Central Florida, Orlando, Florida 32826,1 Departments of Microbiology and Medicine, Columbia University, New York, New York 10032,2 Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 191073

Received 20 March 2009/ Accepted 6 July 2009

The specificity of vesicle-mediated transport is largely regulated by the membrane-specific distribution of SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins. However, the signals and machineries involved in SNARE protein targeting to the respective intracellular locations are not fully understood. We have identified a Sec22 ortholog in Plasmodium falciparum (PfSec22) that contains an atypical insertion of the Plasmodium export element within the N-terminal longin domain. This Sec22 protein partially associates with membrane structures in the parasitized erythrocytes when expressed under the control of the endogenous promoter element. Our studies indicate that the atypical longin domain contains signals that are required for both endoplasmic reticulum (ER)/Golgi apparatus recycling of PfSec22 and partial export beyond the ER/Golgi apparatus interface. ER exit of PfSec22 is regulated by motifs within the {alpha}3 segment of the longin domain, whereas the recycling and export signals require residues within the N-terminal hydrophobic segment. Our data suggest that the longin domain of PfSec22 exhibits major differences from the yeast and mammalian orthologs, perhaps indicative of a novel mechanism for Sec22 trafficking in malaria parasites.

* Corresponding author. Mailing address: 12722 Research Parkway, University of Central Florida, Orlando, FL 32826-3227. Phone: (407) 864-2256. Fax: (407) 384-2062. E-mail: dchak{at}mail.ucf.edu

{triangledown} Published ahead of print on 17 July 2009.

Eukaryotic Cell, September 2009, p. 1330-1340, Vol. 8, No. 9
1535-9778/09/$08.00+0     doi:10.1128/EC.00092-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.





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