Arabidopsis LDIP is an LDAP-interacting protein that influences lipid droplet biogenesis and neutral lipid homeostasis in both leaves and seeds

ABSTRACT: Cytoplasmic lipid droplets (LDs) are found in all types of plant cells where they are derived from the endoplasmic reticulum (ER) and function as a repository for neutral lipids, as well as serving in lipid remodelling and signalling. However, the mechanisms underlying the formation and functioning of plant LDs, particularly in non-seed tissues, are relatively unknown. Previously, we showed that the LD-Associated Proteins (LDAPs) are a family of plant-specific, LD surface-associated coat proteins that are required for proper LD biogenesis and neutral lipid homeostasis in vegetative tissues. Here, we screened a yeast two-hybrid library using Arabidopsis LDAP3 as ‘bait’ in an effort to identify other novel LD protein constituents. One of the candidate LDAP3-interacting proteins was Arabidopsis At5g16550, which is a plant-specific protein of unknown function that we termed LDIP (LDAP-interacting protein). Using a combination of biochemical and cellular approaches, we show that LDIP targets specifically to the LD surface, contains a discrete amphipathic -helical targeting sequence, and participates in both homotypic and heterotypic associations with itself and LDAP3, respectively. Analysis of LDIP T-DNA knockdown and knockout mutants showed a decrease in LD abundance and increase in variability of LD size in leaves, with concomitant increases in total neutral lipid content. Similar phenotypes were observed in plant seeds, which showed enlarged LDs and increases in total seed oil amounts. Collectively, these data identify LDIP as a new player in LD biogenesis in plants that modulates both LD size and cellular neutral lipid homeostasis. Potential mechanisms of LDIP activity are discussed.

INSTRUMENT(S): LTQ Orbitrap Velos

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

TISSUE(S): Seedling

SUBMITTER: Till Ischebeck  

LAB HEAD: Till Ischebeck

PROVIDER: PXD007192 | Pride | 2017-11-06

REPOSITORIES: Pride