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Publication Abstract from PubMed

Most plastids proteins are post-translationally imported into organelles through multisubunit translocons. The TIC and TOC complexes perform this role in the two membranes of the plant chloroplast and in the inner two membranes of the apicoplasts of the apicomplexan parasites, T. gondii and P. falciparum. Tic22 is a ubiquitous intermembrane translocon component that interacts with translocating proteins. Here, we demonstrate that T. gondii Tic22 is an apicoplast-localized protein, essential for parasite survival and protein import into the apicoplast stroma. The structure of Tic22 from P. falciparum reveals a fold conserved from cyanobacteria to plants, which displays a non-polar groove on each sides of the molecule. We show that these grooves allow Tic22 to act as a chaperone. General chaperones are common components of protein translocation systems where they maintain cargo proteins in an unfolded conformation during transit. Such a chaperone had not been identified in the intermembrane space of plastids and we propose that Tic22 fulfils this role.

Tic22 is an essential chaperone required for protein import into the apicoplast.,Glaser S, van Dooren GG, Agrawal S, Brooks CF, McFadden GI, Striepen B, Higgins MK J Biol Chem. 2012 Oct 1. PMID:23027875^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.