title: Identification of the major functional proteins of prokaryotic lipid droplets.
abstract: Storage of cellular triacylglycerols (TAGs) in lipid droplets (LDs) has been linked to the progression of many metabolic diseases in humans, and to the development of biofuels from plants and microorganisms. However, the biogenesis and dynamics of LDs are poorly understood. Compared with other organisms, bacteria seem to be a better model system for studying LD biology, because they are relatively simple and are highly efficient in converting biomass to TAG. We obtained highly purified LDs from Rhodococcus sp. RHA1, a bacterium that can produce TAG from many carbon sources, and then comprehensively characterized the LD proteome. Of the 228 LD-associated proteins identified, two major proteins, ro02104 and PspA, constituted about 15% of the total LD protein. The structure predicted for ro02104 resembles that of apolipoproteins, the structural proteins of plasma lipoproteins in mammals. Deletion of ro02104 resulted in the formation of supersized LDs, indicating that ro02104 plays a critical role in cellular LD dynamics. The putative α helix of the ro02104 LD-targeting domain (amino acids 83-146) is also similar to that of apolipoproteins. We report the identification of 228 proteins in the proteome of prokaryotic LDs, identify a putative structural protein of this organelle, and suggest that apolipoproteins may have an evolutionarily conserved role in the storage and trafficking of neutral lipids.
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Beijing, China; National Laboratory of Biomacromolecules, Graduate University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Yunfeng
authors.initials: Y
authors.lastname: Ding
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Beijing, China; National Laboratory of Biomacromolecules, Graduate University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Li
authors.initials: L
authors.lastname: Yang
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Beijing, China.
authors.forename: Shuyan
authors.initials: S
authors.lastname: Zhang
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Beijing, China; National Laboratory of Biomacromolecules, Graduate University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Wang
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Beijing, China; National Laboratory of Biomacromolecules, Department of Histology and Embryology, University of South China, Hengyang, Hunan Province, China.
authors.forename: Yalan
authors.initials: Y
authors.lastname: Du
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Beijing, China; National Laboratory of Biomacromolecules, Graduate University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Pu
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Beijing, China; National Laboratory of Biomacromolecules, Graduate University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Gong
authors.initials: G
authors.lastname: Peng
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Beijing, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Chen
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Beijing, China.
authors.forename: Huina
authors.initials: H
authors.lastname: Zhang
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Beijing, China; National Laboratory of Biomacromolecules, Graduate University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Jinhai
authors.initials: J
authors.lastname: Yu
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Beijing, China.
authors.forename: Haiying
authors.initials: H
authors.lastname: Hang
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Beijing, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Wu
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Beijing, China.
authors.forename: Fuquan
authors.initials: F
authors.lastname: Yang
authors.affiliation: National Laboratory of Biomacromolecules, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia.
authors.forename: Hongyuan
authors.initials: H
authors.lastname: Yang
authors.affiliation: National Laboratory of Biomacromolecules, Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität, D-48149 Münster, Germany, and King Abdulaziz University, Jeddah, Saudi Arabia. Electronic address: alexander.steinbuechel@uni-muenster.de.
authors.forename: Alexander
authors.initials: A
authors.lastname: Steinbüchel
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Beijing, China. Electronic address: pliu@sun5.ibp.ac.cn.
authors.forename: Pingsheng
authors.initials: P
authors.lastname: Liu
mesh_terms: D001053:Apolipoproteins / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism*; D015153:Blotting, Western; D002855:Chromatography, Thin Layer; D002479:Inclusion Bodies / Q000378:metabolism*; D008055:Lipids / Q000737:chemistry*; D013058:Mass Spectrometry; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D040901:Proteomics / Q000379:methods; D012240:Rhodococcus / Q000378:metabolism; D014280:Triglycerides / Q000378:metabolism
chemical_list: D001053:Apolipoproteins; D001426:Bacterial Proteins; D008055:Lipids; D014280:Triglycerides