A 95 kDa protein of Plasmodium vivax and P. cynomolgi visualized by 3-D tomography in the caveola-vesicle complexes (Sch?ffner's dots) of infected erythrocytes is a member of the PHIST family

• Type of Material: Article
• Authors: Sheila Akinyi, Emory University; Eric Hanssen, The University of Melbourne; Esmeralda V S Meyer, Emory University; Jianlin Jiang, Emory University; Cindy C. Korir, Emory University; Balwan Singh, Emory University; Stacey Lapp, Emory University; John W. Barnwell, Centers for Disease Control and Prevention; Leann Tilley, The University of Melbourne; Mary R Galinski, Emory University
• Language: English
• Date: 2012-06
• Publisher: Wiley: 12 months
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2012 Blackwell Publishing Ltd
• Final Published Version (URL): http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2958.2012.08060.x/abstract
• Title of Journal or Parent Work: Molecular Microbiology
• ISSN: 0950-382X
• Volume: 84
• Issue: 5
• Start Page: 816
• End Page: 831
• Grant/Funding Information: This research was supported by National Institutes of Health grants AI24710, AI096067, and HL0788626 and the Yerkes National Primate Research Center Base grant RR-00165 awarded by the National Center for Research Resources of the National Institutes of Health. SA was also supported by funds from the Australia Research Council and the Australian National Health and Medical Research Council.
• Keywords: Plasmodium; Erythrocytes; Caveolae-Vesicle Complex; Malaria; PHIST; Tomography
• Research Categories: Biology, Microbiology; Biology, Molecular; Health Sciences, Pathology

Abstract

Summary Plasmodium vivax and P. cynomolgi produce numerous caveolae-vesicle complex (CVC) structures within the surface of the infected erythrocyte membrane. These contrast with the electron-dense knob protrusions expressed at the surface of P. falciparum infected erythrocytes. Here we investigate the 3-dimensional structure of the CVCs and the identity of a predominantly expressed 95 kDa CVC protein. Liquid chromatography - tandem mass spectrometry analysis of immunoprecipitates by monoclonal antibodies from P. cynomolgi extracts identified this protein as a member of the Plasmodium helical interspersed sub-telomeric (PHIST) superfamily with a calculated mass of 81 kDa. We named the orthologous proteins PvPHIST/CVC-8195 and PcyPHIST/CVC-8195, analyzed their structural features, including a PEXEL motif, repeated sequences and a C-terminal PHIST domain, and show that PHIST/CVC-8195 is most highly expressed in trophozoites. We generated images of CVCs in 3-D using electron tomography, and used immuno-Electron Tomography (ET) to show PHIST/CVC-8195 localizes to the cytoplasmic side of the CVC tubular extensions. Targeted gene disruptions were attempted in vivo. The pcyphist/cvc-8195 gene was not disrupted, but parasites containing episomes with the tgdhfr selection cassette were retrieved by selection with pyrimethamine. This suggests that PHIST/CVC-8195 is essential for survival of these malaria parasites.