Autophagy genes Smatg8 and Smatg4 are required for fruiting-body development, vegetative growth and ascospore germination in the filamentous ascomycete Sordaria macrospora.
Autophagy is a tightly controlled degradation process involved in various developmental aspects of eukaryotes. However, its involvement in developmental processes of multicellular filamentous ascomycetes is largely unknown. Here, we analyzed the impact of the autophagic proteins SmATG8 and SmATG4 on the sexual and vegetative development of the filamentous ascomycete Sordaria macrospora. A Saccharomyces cerevisiae complementation assay demonstrated that the S. macrospora Smatg8 and Smatg4 genes can functionally replace the yeast homologs. By generating homokaryotic deletion mutants, we showed that the S. macrospora SmATG8 and SmATG4 orthologs were associated with autophagy-dependent processes. Smatg8 and Smatg4 deletions abolished fruiting-body formation and impaired vegetative growth and ascospore germination, but not hyphal fusion. We demonstrated that SmATG4 was capable of processing the SmATG8 precursor. SmATG8 was localized to autophagosomes, whereas SmATG4 was distributed throughout the cytoplasm of S. macrospora. Furthermore, we could show that Smatg8 and Smatg4 are not only required for nonselective macroautophagy, but for selective macropexophagy as well. Taken together, our results suggest that in S. macrospora, autophagy seems to be an essential and constitutively active process to sustain high energy levels for filamentous growth and multicellular development even under nonstarvation conditions.
Institute of Microbiology and Genetics, Department of Genetics of Eukaryotic Microorganisms, Georg-August University, Göttingen, Germany.
Oliver
O
Voigt
Stefanie
S
Pöggeler
D000595:Amino Acid Sequence; D001343:Autophagy / Q000235:genetics* / Q000502:physiology; D000071190:Autophagy-Related Protein 8 Family; D000071183:Autophagy-Related Proteins; D017124:Conserved Sequence; D003593:Cytoplasm / Q000378:metabolism; D048690:Fruiting Bodies, Fungal / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D005800:Genes, Fungal; D005816:Genetic Complementation Test; D025301:Hyphae / Q000235:genetics; D008869:Microtubule-Associated Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D010588:Phagosomes / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D020037:Sordariales / Q000166:cytology / Q000235:genetics* / Q000254:growth & development* / Q000502:physiology; D013045:Species Specificity; D013172:Spores, Fungal / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques
C113757:ATG8 protein, S cerevisiae; C113755:Atg4 protein, S cerevisiae; D000071190:Autophagy-Related Protein 8 Family; D000071183:Autophagy-Related Proteins; D005656:Fungal Proteins; D008869:Microtubule-Associated Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins