E1-like activating enzyme involved in the 2 ubiquitin-like systems required for cytoplasm to vacuole transport (Cvt) and autophagy (PubMed:29417220). Activates ATG12 for its conjugation with ATG5 and ATG8 for its conjugation with phosphatidylethanolamine (By similarity). Both systems are needed for the ATG8 association to Cvt vesicles and autophagosomes membranes (By similarity). Autophagy is essential for maintenance of amino acid levels and protein synthesis under nitrogen starvation. Required for selective autophagic degradation of the nucleus (nucleophagy) as well as for mitophagy which contributes to regulate mitochondrial quantity and quality by eliminating the mitochondria to a basal level to fulfill cellular energy requirements and preventing excess ROS production (By similarity). Required for normal mycelial growth and conidiogenesis, and regulates sclerotial formation (PubMed:29417220). Plays an essential role in pathogenesis (PubMed:29417220). Homodimer (By similarity). Interacts with ATG8 through a thioester bond between Cys-616 and the C-terminal Gly of ATG8 and with ATG12 through a thioester bond between Cys-616 and the C-terminal Gly of ATG12 (By similarity). Interacts also with ATG3 (PubMed:29417220). The C-terminal residues 721 to 760 are required for homodimerization, as well as the interactions with ATG3, ATG8 and ATG12; and the C-terminal 17 residues are required for the ATG8 lipidation (By similarity). The GxGxxG motif is important for the function, possibly through binding with ATP (By similarity). Blocks the autophagic process (PubMed:29417220). Leads to fewer aerial hyphae and slower mycelial growth rate and fails to produce any conidia (PubMed:29417220). Reduces also the production of sclerotia in cold environment (PubMed:29417220). Fails to infect wounded cucumber leaves and shows only slight virulence on wounded tomato and grape fruits (PubMed:29417220). Belongs to the ATG7 family.