Molecular determinants that mediate the sorting of human ATG9A from the endoplasmic reticulum.
ATG9A is a multispanning membrane protein required for autophagosome formation. Under basal conditions, neosynthesized ATG9A proteins travel to the Golgi apparatus and cycle between the trans-Golgi network and endosomes. In the present work, we searched for molecular determinants involved in the subcellular trafficking of human ATG9A in HeLa cells using sequential deletions and point mutations. Deletion of amino acids L(340) to L(354) resulted in the retention of ATG9A in the endoplasmic reticulum. In addition, we found that substitution of the L(711)YM(713) sequence (located in the C-terminal region of ATG9A) by alanine residues severely impaired its transport through the Golgi apparatus. This defect could be corrected by oligomerization of the mutant protein with co-transfected wild-type ATG9A, suggesting that ATG9A oligomerization may help its sorting through biosynthetic compartments. Lastly, the study of the consequences of the LYM/AAA mutation on the intracellular trafficking of ATG9A highlighted that some newly synthesized ATG9A can bypass the Golgi apparatus to reach the plasma membrane. Taken together, these findings provide new insights into the intracellular pathways followed by ATG9A to reach different subcellular compartments, and into the intramolecular determinants that drive the sorting of this protein.
URPhyM-Laboratoire de Chimie Physiologique, Université de Namur, Belgium.
Catherine
C
Staudt
URPhyM-Laboratoire de Chimie Physiologique, Université de Namur, Belgium.
Florentine
F
Gilis
URPhyM-Laboratoire de Chimie Physiologique, Université de Namur, Belgium.
Marielle
M
Boonen
URPhyM-Laboratoire de Chimie Physiologique, Université de Namur, Belgium. Electronic address: michel.jadot@unamur.be.
Michel
M
Jadot
D000595:Amino Acid Sequence; D000071183:Autophagy-Related Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D053898:Biosynthetic Pathways; D002451:Cell Compartmentation; D002462:Cell Membrane / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D011992:Endosomes / Q000378:metabolism; D006031:Glycosylation; D006056:Golgi Apparatus / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D050505:Mutant Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D011134:Polysaccharides / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D055503:Protein Multimerization; D055550:Protein Stability; D021381:Protein Transport; D059748:Proteolysis; D033921:Vesicular Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
C574794:ATG9A protein, human; D000071183:Autophagy-Related Proteins; D008565:Membrane Proteins; D050505:Mutant Proteins; D011134:Polysaccharides; D033921:Vesicular Transport Proteins; D046988:Proteasome Endopeptidase Complex
ATG9A; Endoplasmic reticulum; Intracellular transport; Oligomerization; Sorting signal