Arabidopsis EARLY RESPONSIVE TO DEHYDRATION 7 associates with lipid droplets via its senescence domain

ABSTRACT: Lipid droplets (LDs) are neutral lipid-containing organelles found in all kingdoms of life and are decorated with proteins that carry out a variety of functions. Despite the similar subcellular location, the LD proteins that carry out these functions vary between kingdoms, and only a few LD proteins share obvious amino acid sequence identity between plants and mammals. To better understand the many cellular roles of LDs in plants, a more comprehensive inventory and characterization of LD proteins is required. To this end, we analyzed proteomics data of isolated LDs and identified EARLY RESPONSIVE TO DEHYDRATION 7 (ERD7) as a putative LD protein. mCherry-tagged ERD7 localized to both LDs and to the cytosol when transiently expressed in Nicotiana benthamiana leaves, whereas a fragment of ERD7 containing a “senescence domain” (SD) localized exclusively to LDs with no appreciable accumulation in the cytosol. Similarly, the SDs of the two Arabidopsis ERD7 homologs, here termed SENESCENCE-ASSOCIATED A2 (SENA2) and SENA3, localized exclusively to LDs as did the SD of a phylogenetically distant SD-containing protein, human spartin. In contrast, SDs of the Arabidopsis SENESCENCE-ASSOCIATED B (SENB) family proteins did not localize to LDs and instead localized to mitochondria. Arabidopsis erd7 mutants did not display any observable LD phenotypes in seeds, seedlings or senescent leaves, perhaps due to genetic redundancy of the SENA protein family. A yeast-two-hybrid screen revealed that the S4 family of MYB transcription factors interacts with ERD7, providing a potential avenue for the exploration of ERD7 function. In summary, we here report a previously unappreciated family of plant LD-associated proteins, SENA, which contain SDs that localize to LDs.

INSTRUMENT(S): Q Exactive HF

ORGANISM(S): Arabidopsis Thaliana (mouse-ear Cress)

TISSUE(S): Photosynthetic Cell, Leaf

SUBMITTER: Till Ischebeck  

LAB HEAD: Till Ischebeck

PROVIDER: PXD023047 | Pride | 2021-03-29

REPOSITORIES: Pride