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Arabidopsis lipid droplet‐associated protein (LDAP) – interacting protein ( LDIP ) influences lipid droplet size and neutral lipid homeostasis in both leaves and seeds
Author(s) -
Pyc Michal,
Cai Yingqi,
Gidda Satinder K.,
Yurchenko Olga,
Park Sunjung,
Kretzschmar Franziska K.,
Ischebeck Till,
Valerius Oliver,
Braus Gerhard H.,
Chapman Kent D.,
Dyer John M.,
Mullen Robert T.
Publication year - 2017
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.13754
Subject(s) - arabidopsis , endoplasmic reticulum , microbiology and biotechnology , lipid droplet , biology , gene knockdown , oleosin , mutant , biochemistry , gene
Summary Cytoplasmic lipid droplets ( LD s) are found in all types of plant cells; they are derived from the endoplasmic reticulum and function as a repository for neutral lipids, as well as serving in lipid remodelling and signalling. However, the mechanisms underlying the formation, steady‐state maintenance and turnover of plant LD s, particularly in non‐seed tissues, are relatively unknown. Previously, we showed that the LD ‐associated proteins ( LDAP s) are a family of plant‐specific, LD surface‐associated coat proteins that are required for proper biogenesis of LD s and neutral lipid homeostasis in vegetative tissues. Here, we screened a yeast two‐hybrid library using the Arabidopsis LDAP 3 isoform as ‘bait’ in an effort to identify other novel LD protein constituents. One of the candidate LDAP 3‐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 α‐helical targeting sequence, and participates in both homotypic and heterotypic associations with itself and LDAP 3, respectively. Analysis of LDIP T‐ DNA knockdown and knockout mutants showed a decrease in LD abundance and an 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 LD s and increases in total amounts of seed oil. Collectively, these data identify LDIP as a new player in LD biology that modulates both LD size and cellular neutral lipid homeostasis in both leaves and seeds.