|Page Contents: Abstract|
Karow, Malte, Fischer, Sarah, Me?ling, Susanne, Konertz, Roman, Riehl, Jana, Xiong, Qiuhong, Rijal, Ramesh, Wagle, Prerana, Clemen, CS Christoph S, Eichinger, Ludwig, (2020)
' Functional Characterisation of the Autophagy ATG12~5/16 Complex in Dictyostelium discoideum. '
|Abstract:Macroautophagy, a highly conserved and complex intracellular degradative pathway, involves more than 20 core autophagy (ATG) proteins, among them the hexameric ATG12~5/16 complex, which is part of the essential ubiquitin-like conjugation systems in autophagy. Dictyostelium discoideumatg5 single, atg5/12 double, and atg5/12/16 triple gene knock-out mutant strains displayed similar defects in the conjugation of ATG8 to phosphatidylethanolamine, development, and cell viability upon nitrogen starvation. This implies that ATG5, 12 and 16 act as a functional unit in canonical autophagy. Macropinocytosis of TRITC dextran and phagocytosis of yeast were significantly decreased in ATG5? and ATG5?/12? and even further in ATG5?/12?/16? cells. In contrast, plaque growth on Klebsiella aerogenes was about twice as fast for ATG5? and ATG5?/12?/16? cells in comparison to AX2, but strongly decreased for ATG5?/12? cells. Along this line, phagocytic uptake of Escherichia coli was significantly reduced in ATG5?/12? cells, while no difference in uptake, but a strong increase in membrane association of E. coli, was seen for ATG5? and ATG5?/12?/16? cells. Proteasomal activity was also disturbed in a complex fashion, consistent with an inhibitory activity of ATG16 in the absence of ATG5 and/or ATG12. Our results confirm the essential function of the ATG12~5/16 complex in canonical autophagy, and furthermore are consistent with autophagy-independent functions of the complex and its individual components. They also strongly support the placement of autophagy upstream of the ubiquitin-proteasome system (UPS), as a fully functional UPS depends on autophagy.|
|Status:||epublish||Type:||Journal article||Source:||PUBMED||PubMed ID:||32397394|