AUTHOR=Wang Ya-nan , Liu Fang-jie , Liu Hong-di , Zhang Yue , Jiao Xiang , Ye Ming-liang , Zhao Zong-bao Kent , Zhang Su-fang TITLE=Regulation of autophagy and lipid accumulation under phosphate limitation in Rhodotorula toruloides JOURNAL=Frontiers in Microbiology VOLUME=13 YEAR=2023 URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.1046114 DOI=10.3389/fmicb.2022.1046114 ISSN=1664-302X ABSTRACT=Background

It is known that autophagy is essential for cell survival under stress conditions. Inorganic phosphate (Pi) is an essential nutrient for cell growth and Pi-limitation can trigger autophagy and lipid accumulation in oleaginous yeasts, yet protein (de)-phosphorylation and related signaling events in response to Pi limitation and the molecular basis linking Pi-limitation to autophagy and lipid accumulation remain elusive.

Results

Here, we compared the proteome and phosphoproteome of Rhodotorula toruloides CGMCC 2.1389 under Pi-limitation and Pi-repletion. In total, proteome analysis identified 3,556 proteins and the phosphoproteome analysis identified 1,649 phosphoproteins contained 5,659 phosphosites including 4,499 pSer, 978 pThr, and 182 pTyr. We found Pi-starvation-induced autophagy was regulated by autophagy-related proteins, but not the PHO pathway. When ATG9 was knocked down, the engineered strains produced significantly less lipids under Pi-limitation, suggesting that autophagy required Atg9 in R. toruloides and that was conducive to lipid accumulation.

Conclusion

Our results provide new insights into autophagy regulation under Pi-limitation and lipid accumulation in oleaginous yeast, which should be valuable to guide further mechanistic study of oleaginicity and genetic engineering for advanced lipid producing cell factory.