| Under the conditions of starvation, low energy, hypoxia or Rapamycin, adouble-membrane structure forms in cytosol and engulfs target protein or damagedorganelle, then fuses with lysosome to generate autolysosome in order to degrade theengulfed protein with the acid hydrolase. This process is defined as autophagy.Research shows that autophagy will be induced when cells are treated with HDACinhibitors such as TSA or VPA. This indicates that acetylation plays a crucial role inautophagy regulation.With genetic screening, we found that HAT Esa1and HDAC Rpd3contribute tothe regulation of autophagy. Combining biochemistry, genetic and cell biology analysis,we identified autophagy-related protein ATG3as the substrate of HAT. Then, we usedacetylation immunoprecipitation to prove that Atg3is the substrate of Esa1and Rpd3.K19and K48sites of Atg3are found to be acetylated using mass spectrum. Mutationanalysis of the acetylated sites showed that Atg3K19R and K48R greatly impairautophagy and acetylated Atg3regulates autophagy by influencing its interaction withAtg8, which in turn induces the lipidation of Atg8. Besides, we found that theacetylation level of Atg3increases at the beginning of nitrogen starvation while itdecreases as starvation proceeds. Esa1can bind to PAS and Atg3dynamically and theincrease of Atg3acetylation level will enhance the intensity and duration of autophagy.In conclusion, HAT Esa1contributes to the regulation of autophagy by acetylating Atg3to induce its binding with Atg8，the research provides a soild foundation for furtherstudy about how acetylation regulates autophagy，which also has important theoreticalsignificance on autophagy formation and regulation.We also identified an evolutionarily conserved site K292in Atg3, whose mutationaffects autophagy severely. Further research shows that Atg3-K292R will increase thebinding between Atg3and Atg8dramatically in nitrogen starvation and inhibit thelipidation of Atg8to PE, thus inhibit autophagy. |
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