Evidence for prenylation-dependent targeting of a Ykt6 SNARE in Plasmodium falciparum

• Published in: Molecular and biochemical parasitology Vol. 175; no. 2; pp. 162 - 168
• Main Authors: Ayong, Lawrence, DaSilva, Thiago, Mauser, Jennifer, Allen, Charles M., Chakrabarti, Debopam
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.02.2011; Amsterdam: Elsevier
• Subjects: Amino Acid Motifs; Cytoplasm - chemistry; Erythrocytes - parasitology; Escherichia coli - genetics; Farnesyltranstransferase - metabolism; Golgi Apparatus - chemistry; Intracellular Membranes - chemistry; Microscopy, Confocal; Microscopy, Fluorescence; Mutant Proteins - genetics; Mutant Proteins - metabolism; Plasmodium falciparum; Plasmodium falciparum - metabolism; Prenylation; Protein Prenylation; Protein trafficking; Protein Transport; Sequence Deletion; SNARE; SNARE Proteins - genetics; SNARE Proteins - metabolism; Ykt6; Prenylation; Plasmodium falciparum; Ykt6; SNARE; Protein trafficking
• ISSN: 0166-6851; 1872-9428
• DOI: 10.1016/j.molbiopara.2010.11.007

Our data provide the first experimental evidence for prenylation-dependent transport of Ykt6 in Plasmodium falciparum, and is the first report of geranylgeranylation of a SNARE protein. [Display omitted] ▶ PfYKt6.1 as a substrate for farnesylation and geranylgeranylation. ▶ PfYkt6.1 exhibits prenylation dependent subcellular distribution. ▶ PfYkt6.1 CAAX peptide inhibits Pf farnesyltransferase activity. Ykt6 proteins are the most versatile fusogens in eukaryotic cells, and the only SNAREs that can be both prenylated and acylated at a C-terminal CAAX motif. Unlike yeast and mammalian cells where a single Ykt6 gene is expressed, the Plasmodium falciparum genome encodes two Ykt6 proteins. We have investigated the expression and prenylation of the Ykt6 orthologue, PfYkt6.1 in intra-erythrocytic stages of P. falciparum. PfYkt6.1 localized to the parasite Golgi and other unidentified cytoplasmic compartments, and was partly cytosolic (∼50% in early trophozoites). The membrane-association of PfYkt6.1 was dependent on the presence of a conserved C-terminal CAAX motif (CCSIM). By expressing full-length and mutant proteins in Escherichia coli, we have shown that PfYkt6.1 indeed serves as substrate for prenylation by P. falciparum farnesyltransferases. Surprisingly, PfYkt6.1 could also be geranylgeranylated by parasite extracts independent of the C-terminal amino acid residue. Deletion of the CAAX motif inhibited both farnesylation and geranylgeranylation activities. Additionally, the PfYkt6.1 heptapeptide KQCCSIM, corresponding to the C-terminal CAAX sequence, inhibited the parasite farnesyltransferase activity with an IC50 of 1μM. Our findings underscore the importance of CAAX motif-derived peptidomimetics for antimalarial drug development.