Quantitative live-cell PALM reveals nanoscopic Faa4 redistributions and dynamics on lipid droplets during metabolic transitions of yeast

Santosh Adhikari, Joe Moscatelli, Elias M. Puchner

Research output: Contribution to journalArticlepeer-review

Abstract

Lipid droplets (LDs) are dynamic organelles for lipid storage and homeostasis. Cells respond to metabolic changes by regulating the spatial distribution of LDs and enzymes required for LD growth and turnover. The small size of LDs precludes the observation of their associated enzyme densities and dynamics with conventional fluorescence microscopy. Here we employ quantitative photo-activated localization microscopy to study the density of the fatty acid (FA) activating enzyme Faa4 on LDs in live yeast cells with single-molecule sensitivity and 30 nm resolution. During the log phase LDs colocalize with the endoplasmic reticulum (ER) where their emergence and expansion are mediated by the highest observed Faa4 densities. During transition to the stationary phase, LDs with a ∼2-fold increased surface area translocate to the vacuolar surface and lumen and exhibit a ∼2.5-fold increase in Faa4 density. The increased Faa4 density on LDs further suggests its role in LD expansion, is caused by its ∼5-fold increased expression level, and is specific to exogenous FA chain-lengths. When lipolysis is induced by refreshed medium, Faa4 shuttles through ER- and lipophagy to the vacuole, where it may activate FAs for membrane expansion and degrade Faa4 to reset its cellular abundance to levels in the log phase.

Original languageEnglish (US)
Pages (from-to)1565-1578
Number of pages14
JournalMolecular biology of the cell
Volume32
Issue number17
DOIs
StatePublished - Aug 15 2021

Bibliographical note

Funding Information:
We thank Doug Mashek and his lab as well as Christer Ejsing and Florian Froehlich for helpful discussions. From the Puchner lab, we thank Maria-Paz Ramirez Lopez for making the Sec63 yeast strain. Research reported in this publication was supported by the National Institute of General Medical Sciences of the National Institutes of Health under Award number R21GM127965.

Publisher Copyright:
© 2021 Adhikari et al.

PubMed: MeSH publication types

  • Journal Article
  • Research Support, N.I.H., Extramural

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