Experimental Determination of the Membrane Topology of the Plasmodium Protease Plasmepsin V

PLoS One

Andrew R. Osborne¹  Sarah J. Tarr¹ 

[1] Institute of Structural and Molecular Biology, Division of Biosciences, Birkbeck and University College London, London, United Kingdom

关键词: Endoplasmic reticulum;    Plasmodium;    Cytosol;    Fluorescence imaging;    Proteases;    Red blood cells;    Immunoblotting;    Malarial parasites;   

DOI  :  10.1371/journal.pone.0121786

学科分类：医学（综合）

来源: Public Library of Science

【 摘 要 】

The malaria parasite exports hundreds of proteins into its host cell. The majority of exported proteins contain a Host-Targeting motif (also known as a Plasmodium export element) that directs them for export. Prior to export, the Host-Targeting motif is cleaved by the endoplasmic reticulum-resident protease Plasmepsin V and the newly generated N-terminus is N-α-acetylated by an unidentified enzyme. The cleaved, N-α-acetylated protein is trafficked to the parasitophorous vacuole, where it is translocated across the vacuole membrane. It is clear that cleavage and N-α-acetylation of the Host-Targeting motif occur at the endoplasmic reticulum, and it has been proposed that Host-Targeting motif cleavage and N-α-acetylation occur either on the luminal or cytosolic side of the endoplasmic reticulum membrane. Here, we use self-associating ‘split’ fragments of GFP to determine the topology of Plasmepsin V in the endoplasmic reticulum membrane; we show that the catalytic protease domain of Plasmepsin V faces the endoplasmic reticulum lumen. These data support a model in which the Host-Targeting motif is cleaved and N-α-acetylated in the endoplasmic reticulum lumen. Furthermore, these findings suggest that cytosolic N-α-acetyltransferases are unlikely to be candidates for the N-α-acetyltransferase of Host-Targeting motif-containing exported proteins.

【 授权许可】

CC BY