Open AccessAutophagy-Associated Protein SmATG12 Is Required for Fruiting-Body Formation in the Filamentous Ascomycete Sordaria macrospora
Author(s) -
A. Werner,
Britta Herzog,
Stefan Frey,
Stefanie Pöggeler
Publication year - 2016
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0157960
Subject(s) - atg8 , biology , autophagy , vacuole , microbiology and biotechnology , atg12 , autophagosome , hypha , atg5 , ubiquitin , cytoplasm , gene , biochemistry , apoptosis
In filamentous fungi, autophagy functions as a catabolic mechanism to overcome starvation and to control diverse developmental processes under normal nutritional conditions. Autophagy involves the formation of double-membrane vesicles, termed autophagosomes that engulf cellular components and bring about their degradation via fusion with vacuoles. Two ubiquitin-like (UBL) conjugation systems are essential for the expansion of the autophagosomal membrane: the UBL protein ATG8 is conjugated to the lipid phosphatidylethanolamine and the UBL protein ATG12 is coupled to ATG5. We recently showed that in the homothallic ascomycete Sordaria macrospora autophagy-related genes encoding components of the conjugation systems are required for fruiting-body development and/or are essential for viability. In the present work, we cloned and characterized the S . macrospora (Sm)atg12 gene. Two-hybrid analysis revealed that SmATG12 can interact with SmATG7 and SmATG3. To examine its role in S . macrospora , we replaced the open reading frame of Smatg12 with a hygromycin resistance cassette and generated a homokaryotic ΔSmatg12 knockout strain, which displayed slower vegetative growth under nutrient starvation conditions and was unable to form fruiting bodies. In the hyphae of S . macrospora EGFP-labeled SmATG12 was detected in the cytoplasm and as punctate structures presumed to be phagophores or phagophore assembly sites. Delivery of EGFP-labelled SmATG8 to the vacuole was entirely dependent on SmATG12.