title: Dissecting the function of Atg1 complex in Dictyostelium autophagy reveals a connection with the pentose phosphate pathway enzyme transketolase.
abstract: The network of protein-protein interactions of the Dictyostelium discoideum autophagy pathway was investigated by yeast two-hybrid screening of the conserved autophagic proteins Atg1 and Atg8. These analyses confirmed expected interactions described in other organisms and also identified novel interactors that highlight the complexity of autophagy regulation. The Atg1 kinase complex, an essential regulator of autophagy, was investigated in detail here. The composition of the Atg1 complex in D. discoideum is more similar to mammalian cells than to Saccharomyces cerevisiae as, besides Atg13, it contains Atg101, a protein not conserved in this yeast. We found that Atg101 interacts with Atg13 and genetic disruption of these proteins in Dictyostelium leads to an early block in autophagy, although the severity of the developmental phenotype and the degree of autophagic block is higher in Atg13-deficient cells. We have also identified a protein containing zinc-finger B-box and FNIP motifs that interacts with Atg101. Disruption of this protein increases autophagic flux, suggesting that it functions as a negative regulator of Atg101. We also describe the interaction of Atg1 kinase with the pentose phosphate pathway enzyme transketolase (TKT). We found changes in the activity of endogenous TKT activity in strains lacking or overexpressing Atg1, suggesting the presence of an unsuspected regulatory pathway between autophagy and the pentose phosphate pathway in Dictyostelium that seems to be conserved in mammalian cells.
authors.affiliation: Instituto de Investigaciones Biomédicas Alberto Sols, CSIC/UAM, Madrid, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Mesquita
authors.affiliation: Instituto de Investigaciones Biomédicas Alberto Sols, CSIC/UAM, Madrid, Spain.
authors.forename: Luis C
authors.initials: LC
authors.lastname: Tábara
authors.affiliation: Instituto de Investigaciones Biomédicas Alberto Sols, CSIC/UAM, Madrid, Spain.
authors.forename: Oscar
authors.identifier: http://orcid.org/0000-0003-4893-2205
authors.initials: O
authors.lastname: Martinez-Costa
authors.affiliation: Instituto de Investigaciones Biomédicas Alberto Sols, CSIC/UAM, Madrid, Spain.
authors.forename: Natalia
authors.initials: N
authors.lastname: Santos-Rodrigo
authors.affiliation: Instituto de Investigaciones Biomédicas Alberto Sols, CSIC/UAM, Madrid, Spain.
authors.forename: Olivier
authors.identifier: http://orcid.org/0000-0003-4355-5367
authors.initials: O
authors.lastname: Vincent
authors.affiliation: Instituto de Investigaciones Biomédicas Alberto Sols, CSIC/UAM, Madrid, Spain rescalante@iib.uam.es.
authors.forename: Ricardo
authors.identifier: http://orcid.org/0000-0001-8547-531X
authors.initials: R
authors.lastname: Escalante
mesh_terms: D001343:Autophagy; D015415:Biomarkers; D002352:Carrier Proteins; D004023:Dictyostelium / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D017930:Genes, Reporter; D042541:Intracellular Space / Q000378:metabolism; D009154:Mutation; D010427:Pentose Phosphate Pathway; D011485:Protein Binding; D025941:Protein Interaction Mapping / Q000379:methods; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits; D021381:Protein Transport; D015203:Reproducibility of Results; D014174:Transketolase / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D025801:Ubiquitin / Q000378:metabolism
chemical_list: D015415:Biomarkers; D002352:Carrier Proteins; D021122:Protein Subunits; D025801:Ubiquitin; D014174:Transketolase; D017346:Protein Serine-Threonine Kinases
keywords: Atg1 complex; Atg101; Atg8; Dictyostelium; autophagy; transketolase