Identification of a palmitoyl acyltransferase required for protein sorting to the flagellar membrane.
Protein palmitoylation has diverse effects in regulating protein membrane affinity, localization, binding partner interactions, turnover and function. Here, we show that palmitoylation also contributes to the sorting of proteins to the eukaryotic flagellum. African trypanosomes are protozoan pathogens that express a family of unique Ca(2+)-binding proteins, the calflagins, which undergo N-terminal myristoylation and palmitoylation. The localization of calflagins depends on their acylation status. Myristoylation alone is sufficient for membrane association, but, in the absence of palmitoylation, the calflagins localize to the pellicular (cell body) membrane. Palmitoylation, which is mediated by a specific palmitoyl acyltransferase, is then required for subsequent trafficking of calflagin to the flagellar membrane. Coincident with the redistribution of calflagin from the pellicular to the flagellar membrane is their association with lipid rafts, which are highly enriched in the flagellar membrane. Screening of candidate palmitoyl acyltranferases identified a single enzyme, TbPAT7, that is necessary for calflagin palmitoylation and flagellar membrane targeting. Our results implicate protein palmitoylation in flagellar trafficking, and demonstrate the conservation and specificity of palmitoyl acyltransferase activity by DHHC-CRD proteins across kingdoms.
Emmer
Brian T
BT
Departments of Pathology and Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
Souther
Christina
C
Toriello
Krista M
KM
Olson
Cheryl L
CL
Epting
Conrad L
CL
Engman
David M
DM
D000215:Acylation; D000217:Acyltransferases / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001710:Biotin / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000201:enzymology*; D005407:Flagella / Q000201:enzymology*; D017125:Genes, Protozoan; D007700:Kinetics; D054878:Lipoylation; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009154:Mutation / Q000235:genetics; D019814:Myristic Acid / Q000378:metabolism; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D015800:Protozoan Proteins / Q000737:chemistry / Q000378:metabolism*; D014346:Trypanosoma brucei brucei / Q000166:cytology* / Q000201:enzymology* / Q000235:genetics
D002135:Calcium-Binding Proteins; D015800:Protozoan Proteins; C061478:flagellar calcium-binding protein, Trypanosoma cruzi; D019814:Myristic Acid; D001710:Biotin; D000217:Acyltransferases