title: Arabidopsis homologues of the autophagy protein Atg8 are a novel family of microtubule binding proteins.
abstract: Autophagy is the non-selective transport of proteins and superfluous organelles destined for degradation to the vacuole in fungae, or the lysosome in animal cells. Some of the genes encoding components of the autophagy pathway are conserved in plants, and here we show that Arabidopsis homologues of yeast Atg8 (Apg8/Aut7) and Atg4 (Apg4/Aut2) partially complement the yeast deletion strains. The yeast double mutant, a deletion strain with respect to both Atg8 and Atg4, could not be complemented by Arabidopsis Atg8, indicating that Arabidopsis Atg8 requires Atg4 for its function. Moreover, Arabidopsis Atg8 and Arabidopsis Atg4 interact directly in a two-hybrid assay. Interestingly, Atg8 shows significant homology with the microtubule binding light chain 3 of MAP1A and B, and here we show that Arabidopsis Atg8 binds microtubules. Our results demonstrate that a principle component of the autophagic pathway in plants is similar to that in yeast and we suggest that microtubule binding plays a role in this process.
authors.affiliation: The Integrative Cell Biology Laboratory, School of Biological and Biomedical Sciences, University of Durham, South Road, Durham DH1 3LE, UK.
authors.forename: Tijs
authors.initials: T
authors.lastname: Ketelaar
authors.forename: Christiane
authors.initials: C
authors.lastname: Voss
authors.forename: Simon A
authors.initials: SA
authors.lastname: Dimmock
authors.forename: Michael
authors.initials: M
authors.lastname: Thumm
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Hussey
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D001343:Autophagy / Q000235:genetics* / Q000502:physiology; D005816:Genetic Complementation Test; D008869:Microtubule-Associated Proteins / Q000235:genetics* / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism* / Q000648:ultrastructure; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D017385:Sequence Homology; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; D008869:Microtubule-Associated Proteins; D009842:Oligopeptides; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; C587254:asparagyl-tyrosyl-glutaminyl-glutaminyl-asparagine