Stable oil bodies sheltered by a unique caleosin in cycad megagametophytes

Jiang, Pei-Luen; Chen, Jeff C.F.; Chiu, Sherry Yueh‐Hsia; Tzen, Jason T.C.

doi:10.1016/j.plaphy.2009.07.004

Cited by 36 publications

(23 citation statements)

References 29 publications

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“…Caleosin is also found in more primitive species, such as cycad and microalgae, and thus is assumed to be an oil-body protein more primitive than oleosin in evolution [95,139]. Phylogenetic tree analysis supports that microalgal caleosin is the most primitive caleosin found in oil bodies to date [8,23,139].…”

Section: Caleosin Isoformsmentioning

confidence: 79%

“…The structural role of caleosin is clearly verified by the observation of stable cycad (Cycas revoluta) seed oil bodies that are mainly sheltered by caleosin without the presence of any oleosin isoform [95]. The investigation also invalidates a prevalent concept in this research area for two decades, declaring that oleosin is an essential constituent and can be regarded as a marker protein of plant oil bodies.…”

Section: Proposed Functions Of Caleosinmentioning

confidence: 95%

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Integral Proteins in Plant Oil Bodies

Tzen

2012

ISRN Botany

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Hydrophobic storage neutral lipids are stably preserved in specialized organelles termed oil bodies in the aqueous cytosolic compartment of plant cells via encapsulation with surfactant molecules including phospholipids and integral proteins. To date, three classes of integral proteins, termed oleosin, caleosin, and steroleosin, have been identified in oil bodies of angiosperm seeds. Proposed structures, targeting traffic routes, and biological functions of these three integral oil-body proteins were summarized and discussed. In the viewpoint of evolution, isoforms of oleosin and caleosin are found in oil bodies of pollens as well as those of more primitive species; moreover, caleosin-and steroleosin-like proteins are also present in other subcellular locations besides oil bodies. Technically, artificial oil bodies of structural stability similar to native ones were successfully constituted and seemed to serve as a useful tool for both basic research studies and biotechnological applications.

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Section: Caleosin Isoformsmentioning

confidence: 79%

Section: Proposed Functions Of Caleosinmentioning

confidence: 95%

Integral Proteins in Plant Oil Bodies

Tzen

2012

ISRN Botany

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“…The biological functions of caleosins have been shown to stabilize the oil body (alias of lipid droplet) of cycad megagametophytes (42) and to interact with vacuoles and promote degradation of storage lipids in Arabidopsis seeds (43). These results suggested that LD structural proteins are likely conserved between diverse eukaryotic species.…”

Section: Resultsmentioning

confidence: 98%

Dynamics of the Lipid Droplet Proteome of the Oleaginous Yeast Rhodosporidium toruloides

et al. 2015

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c Lipid droplets (LDs) are ubiquitous organelles that serve as a neutral lipid reservoir and a hub for lipid metabolism. Manipulating LD formation, evolution, and mobilization in oleaginous species may lead to the production of fatty acid-derived biofuels and chemicals. However, key factors regulating LD dynamics remain poorly characterized. Here we purified the LDs and identified LD-associated proteins from cells of the lipid-producing yeast Rhodosporidium toruloides cultured under nutrient-rich, nitrogen-limited, and phosphorus-limited conditions. The LD proteome consisted of 226 proteins, many of which are involved in lipid metabolism and LD formation and evolution. Further analysis of our previous comparative transcriptome and proteome data sets indicated that the transcription level of 85 genes and protein abundance of 77 proteins changed under nutrient-limited conditions. Such changes were highly relevant to lipid accumulation and partially confirmed by reverse transcription-quantitative PCR. We demonstrated that the major LD structure protein Ldp1 is an LD marker protein being upregulated in lipid-rich cells. When overexpressed in Saccharomyces cerevisiae, Ldp1 localized on the LD surface and facilitated giant LD formation, suggesting that Ldp1 plays an important role in controlling LD dynamics. Our results significantly advance the understanding of the molecular basis of lipid overproduction and storage in oleaginous yeasts and will be valuable for the development of superior lipid producers. Lipid droplets (LDs), intracellular organelles with deposits of neutral lipids and involved in many cellular activities, are widely present in both eukaryotic and prokaryotic cells (1-4). These organelles consist of a neutral lipid core surrounded by a phospholipid monolayer and associated proteins (3, 5). It has been known that LDs serve as the energy reservoir of cells, which may increase the adaptation by mobilization and degradation of lipids during nutrient deprivation, and also connect with other cellular processes, including lipid transport, membrane biogenesis, lipotoxicity relief, protein storage and degradation, pathogenicity, and autophagy (6-9). Because the biology of LDs is closely linked to some diseases, such as obesity, type 2 diabetes, and atherosclerosis, great progress has been made in elucidating the cellular trafficking, dynamics, and biogenesis of LDs in mammalian cells (2, 7, 10). However, there have been few studies on LDs in other species, especially naturally lipid-producing microorganisms (11-13). Analysis of these microorganisms is motivated by the fact that microbial lipid production holds a great promise to convert waste materials, including lignocellulosic biomass, into fatty acid-derived fuel molecules and chemicals in a scenario of biorefinery and sustainable development (14, 15).The major components of LDs are neutral lipids, including triacylglycerols (TAGs), sterol esters, and ether lipids (16). Neutral lipids constitute more than 90% of LDs by weight, but the ratio of TAGs to ste...

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“…Caleosins were fi rst reported as minor constituents of purifi ed LDs from sesame seeds ( 56 ) but have since been found associated with LDs from seeds of many different plant species (57)(58)(59)(60). Like oleosins, caleosins contain a long, central hydrophobic hairpin structure that contains a proline knot motif for LD association.…”

Section: Caleosinsmentioning

confidence: 99%

“…Evidence for a role of caleosin in structural maintenance of LDs is based in part on observations that certain lower plant species such as cycads (sago palms) contain caleosin, rather than oleosin, as their major LD-associated protein ( 59,62 ). Caleosins can also bind to and stabilize artifi cial LDs in vitro ( 41,63 ), and suppression of oleosin genes in soybean (via RNAi) results in a corresponding increase in the amount of caleosin proteins in LDs ( 32 ).…”

Section: Steroleosinsmentioning

confidence: 99%

Biogenesis and functions of lipid droplets in plants

Chapman

Dyer

Mullen

2012

Journal of Lipid Research

331

162

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Journal of Lipid Research Volume 53, 2012 215developing seeds and other plant tissues that contribute to the synthesis of TAGs, although the relative contributions of these alternative pathways to TAG accumulation may vary depending on the tissue and/or species ( 1 ).There also has been a growing appreciation in the past few years that the compartmentation of neutral lipids in LDs of plants extends well beyond their role as simply static depots for carbon storage in seeds and, consequently, there is renewed interest in the cellular ontogeny and dynamics of this organelle. For instance, LDs are observed in nearly all cell types in plants, and although the biogenesis of LDs in nonseed tissues is still poorly understood, we now know that they are involved in many unique processes, such as stress response, pathogen resistance, and hormone metabolism. Furthermore, there are highly specialized roles for LDs in anther development, wherein LDs contribute signifi cantly to the formation of the hydrophobic barrier of the pollen coat as tapetal tissues undergo programmed cell death. Interestingly, this process is somewhat similar to the specialized role that LDs play in the formation of the hydrophobic barrier that comprises the outer layer of mammalian skin.Overall, knowledge of LD function in both seed and nonseed tissues has been greatly enhanced by efforts to characterize the major proteins that specifi cally associate with these organelles, namely oleosins, caleosins, and sterol dehydrogenases (steroleosins) ( Fig. 1 ). Here, after a brief description of LD biogenesis in plant cells, we review the functional properties of these major LD-associated proteins and discuss how they compare with the properties of their known or potential counterparts in yeasts and mammals. We also describe the specialized role of LDs in pollen coat formation and how this process has some The seeds of plants store signifi cant amounts of neutral lipids, namely triacylglycerols (TAGs), in cytosolic lipid droplets (LDs), most of which are subsequently mobilized immediately after germination in order to fuel the growth and development of the seedling prior to photosynthetic establishment. In developing seeds, TAGs are assembled in the endoplasmic reticulum (ER) from acyl-CoAs and glycerol by the conserved "Kennedy" pathway that operates in all eukaryotes. Recently, however, additional acylCoA-independent reactions have been identifi ed in

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Stable oil bodies sheltered by a unique caleosin in cycad megagametophytes

Cited by 36 publications

References 29 publications

Integral Proteins in Plant Oil Bodies

Integral Proteins in Plant Oil Bodies

Dynamics of the Lipid Droplet Proteome of the Oleaginous Yeast Rhodosporidium toruloides

Biogenesis and functions of lipid droplets in plants

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