Lipid droplets in Arabidopsis thaliana leaves contain myosin-binding proteins and enzymes associated with furan-containing fatty acid biosynthesis

Yuto Omata; Reina Sato; Emi Mishiro-Sato; Keiko Kano; Haruko Ueda; Ikuko Hara-Nishimura; Takashi L Shimada

doi:10.3389/fpls.2024.1331479

Lipid droplets in Arabidopsis thaliana leaves contain myosin-binding proteins and enzymes associated with furan-containing fatty acid biosynthesis

Front Plant Sci. 2024 Mar 1:15:1331479. doi: 10.3389/fpls.2024.1331479. eCollection 2024.

Authors

Yuto Omata¹, Reina Sato¹, Emi Mishiro-Sato², Keiko Kano², Haruko Ueda³, Ikuko Hara-Nishimura³, Takashi L Shimada^{1

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Affiliations

¹ Faculty of Horticulture, Chiba University, Matsudo, Japan.
² World Premier International Research Center Initiative-Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, Japan.
³ Faculty of Science and Engineering, Konan University, Kobe, Japan.
⁴ Graduate School of Horticulture, Chiba University, Matsudo, Japan.
⁵ Plant Molecular Science Center, Chiba University, Chiba, Japan.
⁶ Research Center for Space Agriculture and Horticulture, Chiba University, Matsudo, Japan.

Abstract

Lipid droplets (LDs) are lipid storage organelles in plant leaves and seeds. Seed LD proteins are well known, and their functions in lipid metabolism have been characterized; however, many leaf LD proteins remain to be identified. We therefore isolated LDs from leaves of the leaf LD-overaccumulating mutant high sterol ester 1 (hise1) of Arabidopsis thaliana by centrifugation or co-immunoprecipitation. We then performed LD proteomics by mass spectrometry and identified 3,206 candidate leaf LD proteins. In this study, we selected 31 candidate proteins for transient expression assays using a construct encoding the candidate protein fused with green fluorescent protein (GFP). Fluorescence microscopy showed that MYOSIN BINDING PROTEIN14 (MYOB14) and two uncharacterized proteins localized to LDs labeled with the LD marker. Subcellular localization analysis of MYOB family members revealed that MYOB1, MYOB2, MYOB3, and MYOB5 localized to LDs. LDs moved along actin filaments together with the endoplasmic reticulum. Co-immunoprecipitation of myosin XIK with MYOB2-GFP or MYOB14-GFP suggested that LD-localized MYOBs are involved in association with the myosin XIK-LDs. The two uncharacterized proteins were highly similar to enzymes for furan fatty acid biosynthesis in the photosynthetic bacterium Cereibacter sphaeroides, suggesting a relationship between LDs and furan fatty acid biosynthesis. Our findings thus reveal potential molecular functions of LDs and provide a valuable resource for further studies of the leaf LD proteome.

Keywords: Arabidopsis thaliana; actin filament; endoplasmic reticulum; enzymes for furan-containing fatty acid biosynthesis; lipid droplet proteomics; myosin-binding protein.

Grants and funding

The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. This work was supported by Grants-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (JSPS) to TS (nos. 19K05809 and 23K17986), HU (nos. 19K06732 and 18H05496), and IH-N (no. 15H05776); Kato Memorial Bioscience Foundation (to TS); a SUNBOR GRANT from the Suntory Foundation for Life Sciences (to TS); Takeda Science Foundation (to TS); a research grant from The Yanmar Environmental Sustainability Support Association to TS; Inamori Foundation (to TS); JGC-S Scholarship Foundation (to TS); the Leading Initiative for Excellent Young Researchers (LEADER) from the Ministry of Education, Culture, Sports, Science and Technology in Japan (MEXT) to TS (no. J16HJ00026); the Phytochemical Plant Molecular Science of Strategic Priority Research Promotion Program from Chiba University (to TS and KS); and the Hirao Taro Foundation of KONAN GAKUEN for Academic Research (to HU and IH-N).