Experimental determination of the membrane topology of the Plasmodium protease Plasmepsin V.

ABSTRACT: 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-?-acetylated by an unidentified enzyme. The cleaved, N-?-acetylated protein is trafficked to the parasitophorous vacuole, where it is translocated across the vacuole membrane. It is clear that cleavage and N-?-acetylation of the Host-Targeting motif occur at the endoplasmic reticulum, and it has been proposed that Host-Targeting motif cleavage and N-?-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-?-acetylated in the endoplasmic reticulum lumen. Furthermore, these findings suggest that cytosolic N-?-acetyltransferases are unlikely to be candidates for the N-?-acetyltransferase of Host-Targeting motif-containing exported proteins.

SUBMITTER: Tarr SJ 

PROVIDER: S-EPMC4388684 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature