Protein import into the Leishmania glycosome requires docking of the cargo-loaded peroxin 5 (PEX5) receptor to the peroxin 14 (PEX14) bound to the glycosome surface. To examine the LdPEX14–membrane interaction, we purified L. donovani promastigote glycosomes and determined the phospholipid and fatty acid composition. These membranes contained predominately phosphatidylethanolamine, phosphatidylcholine, and phosphatidylglycerol (PG) modified primarily with C18 and C22 unsaturated fatty acid. Using large unilamellar vesicles (LUVs) with a lipid composition mimicking the glycosomal membrane in combination with sucrose density centrifugation and fluorescence-activated cell sorting technique, we established that the LdPEX14 membrane-binding activity was dependent on a predicted transmembrane helix found within residues 149–179. Monolayer experiments showed that the incorporation of PG and phospholipids with unsaturated fatty acids, which increase membrane fluidity and favor a liquid expanded phase, facilitated the penetration of LdPEX14 into biological membranes. Moreover, we demonstrated that the binding of LdPEX5 receptor or LdPEX5–PTS1 receptor–cargo complex was contingent on the presence of LdPEX14 at the surface of LUVs.
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Cover Image
Cover Image
In this issue of the Biochemical Journal, Dukic et al. report that ezrin-anchored PKA phosphorylates serine 369 and 373 on connexin 43 to enhance gap junction assembly, communication, and cell fusion. The cover image, taken from Figure 6 in the article, shows HEK293 cells transfected with mammalian expression vectors encoding siRNA-resistant Cx43 without ability to bind to ezrin and with a phosphomimicking S to D substitution in residue 369.
The hydrophobic region of the Leishmania peroxin 14: requirements for association with a glycosome mimetic membrane
Normand Cyr, Terry K. Smith, Élodie Boisselier, Louis-Philippe Leroux, Anwar Hasil Kottarampatel, Amanda Davidsen, Christian Salesse, Armando Jardim; The hydrophobic region of the Leishmania peroxin 14: requirements for association with a glycosome mimetic membrane. Biochem J 31 January 2018; 475 (2): 511–529. doi: https://doi.org/10.1042/BCJ20170746
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