A conserved glycine residue in the C-terminal region of human ATG9A is required for its transport from the endoplasmic reticulum to the Golgi apparatus.
ATG9A is the only polytopic protein of the mammalian autophagy-related protein family whose members regulate autophagosome formation during macroautophagy. At steady state, ATG9A localizes to several intracellular sites, including the Golgi apparatus, endosomes and the plasma membrane, and it redistributes towards autophagosomes upon autophagy induction. Interestingly, the transport of yeast Atg9 to the pre-autophagosomal structure depends on its self-association, which is mediated by a short amino acid motif located in the C-terminal region of the protein. Here, we investigated whether the residues that align with this motif in human ATG9A (V515-C519) are also required for its trafficking in mammalian cells. Interestingly, our findings support that human ATG9A self-interacts as well, and that this process promotes transport of ATG9A molecules through the Golgi apparatus. Furthermore, our data reveal that the transport of ATG9A out of the ER is severely impacted after mutation of the conserved V515-C519motif. Nevertheless, the mutated ATG9A molecules could still interact with each other, indicating that the molecular mechanism of self-interaction differs in mammalian cells compared to yeast. Using sequential amino acid substitutions of glycine 516 and cysteine 519, we found that the stability of ATG9A relies on both of these residues, but that only the former is required for efficient transport of human ATG9A from the endoplasmic reticulum to the Golgi apparatus.
URPhyM-Laboratoire de Chimie Physiologique, University of Namur, 61 Rue de Bruxelles, 5000 Namur, Belgium.
Catherine
C
Staudt
URPhyM-Laboratoire de Chimie Physiologique, University of Namur, 61 Rue de Bruxelles, 5000 Namur, Belgium.
Florentine
F
Gilis
URPhyM-Laboratoire de Chimie Physiologique, University of Namur, 61 Rue de Bruxelles, 5000 Namur, Belgium.
Virginie
V
Tevel
URPhyM-Laboratoire de Chimie Physiologique, University of Namur, 61 Rue de Bruxelles, 5000 Namur, Belgium.
Michel
M
Jadot
URPhyM-Laboratoire de Chimie Physiologique, University of Namur, 61 Rue de Bruxelles, 5000 Namur, Belgium. Electronic address: marielle.boonen@unamur.be.
Marielle
M
Boonen
D000409:Alanine / Q000737:chemistry; D020816:Amino Acid Motifs; D000071183:Autophagy-Related Proteins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D003545:Cysteine / Q000737:chemistry; D004721:Endoplasmic Reticulum / Q000378:metabolism; D017353:Gene Deletion; D005998:Glycine / Q000737:chemistry*; D006056:Golgi Apparatus / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D000072417:Protein Domains; D021381:Protein Transport; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism*
C574794:ATG9A protein, human; D000071183:Autophagy-Related Proteins; D008565:Membrane Proteins; D033921:Vesicular Transport Proteins; D003545:Cysteine; D000409:Alanine; D005998:Glycine
ATG9A; Endoplasmic reticulum; Self-interaction; Subcellular trafficking