Differential palmitoylation of the endosomal SNAREs syntaxin 7 and syntaxin 8.
Palmitoylation is a posttranslational modification that regulates protein trafficking and stability. In this study we investigated whether the endosomal soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNARE) proteins syntaxin 7 and syntaxin 8 are modified with palmitate. Using metabolic labeling and site-directed mutagenesis, we show that human syntaxins 7 and 8 are modified with palmitate through a thioester linkage. Palmitoylation is dependent upon cysteine 239 of human syntaxin 7 and cysteine 214 of syntaxin 8, residues that are located on the cytoplasmic face of the transmembrane domain (TMD). Palmitoylation of syntaxin 8 is minimally affected by the Golgi-disturbing agent brefeldin A (BFA), whereas BFA dramatically inhibits palmitoylation of syntaxin7. The differential effect of BFA suggests that palmitoylation of syntaxins 7 and 8 occurs in distinct subcellular compartments. Palmitoylation does not affect the rate of protein turnover of syntaxins 7 and 8 nor does it influence the steady-state localization of syntaxin 8 in late endosomes. Syntaxin 7 actively cycles between endosomes and the plasma membrane. Palmitoylation-defective syntaxin 7 is selectively retained on the plasma membrane, suggesting that palmitoylation is important for intercompartmental transport of syntaxin 7.
He
Yuhong
Y
Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110.
Linder
Maurine E
ME
Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110. Electronic address: mlinder@wustl.edu.
D020126:Brefeldin A / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D011992:Endosomes / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006207:Half-Life; D006367:HeLa Cells; D006801:Humans; D054878:Lipoylation / Q000187:drug effects; D018613:Microscopy, Confocal; D046912:Multiprotein Complexes; D016297:Mutagenesis, Site-Directed; D050765:Qa-SNARE Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014162:Transfection
D018076:DNA, Complementary; D046912:Multiprotein Complexes; D050765:Qa-SNARE Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D020126:Brefeldin A