Staying in touch: the molecular era of organelle contact sites

Elbaz, Yael; Schuldiner, Maya

doi:10.1016/j.tibs.2011.08.004

Cited by 207 publications

(156 citation statements)

References 75 publications

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“…Although the exact trafficking mechanism remains unclear, it is possible that this transfer is facilitated by the direct physical association between the membranes of the ER and the chloroplast outer envelope. In support of this possibility, ER-chloroplast membrane contact sites have been reported in a number of microscopy studies (Wang and Benning, 2012), and interorganelle contact sites have been proposed as possible conduits for the trafficking of lipids and other metabolites in plants (Andersson et al, 2007) and other eukaryotes (Levine and Loewen, 2006;Elbaz and Schuldiner, 2011). Alternatively, DGAT1 or the soluble DGAT3 may be involved in the acylation of DAG derived from SFR2 into TAG at the outer chloroplast envelope.…”

Section: Pdat1 and Sdp1 Function Cooperatively In Directing Fas Towarmentioning

confidence: 86%

Arabidopsis Lipins, PDAT1 Acyltransferase, and SDP1 Triacylglycerol Lipase Synergistically Direct Fatty Acids toward β-Oxidation, Thereby Maintaining Membrane Lipid Homeostasis

et al. 2014

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Triacylglycerol (TAG) metabolism is a key aspect of intracellular lipid homeostasis in yeast and mammals, but its role in vegetative tissues of plants remains poorly defined. We previously reported that PHOSPHOLIPID:DIACYLGLYCEROL ACYLTRANSFERASE1 (PDAT1) is crucial for diverting fatty acids (FAs) from membrane lipid synthesis to TAG and thereby protecting against FA-induced cell death in leaves. Here, we show that overexpression of PDAT1 enhances the turnover of FAs in leaf lipids. Using the trigalactosyldiacylglycerol1-1 (tgd1-1) mutant, which displays substantially enhanced PDAT1-mediated TAG synthesis, we demonstrate that disruption of SUGAR-DEPENDENT1 (SDP1) TAG lipase or PEROXISOMAL TRANSPORTER1 (PXA1) severely decreases FA turnover, leading to increases in leaf TAG accumulation, to 9% of dry weight, and in total leaf lipid, by 3-fold. The membrane lipid composition of tgd1-1 sdp1-4 and tgd1-1 pxa1-2 double mutants is altered, and their growth and development are compromised. We also show that two Arabidopsis thaliana lipin homologs provide most of the diacylglycerol for TAG synthesis and that loss of their functions markedly reduces TAG content, but with only minor impact on eukaryotic galactolipid synthesis. Collectively, these results show that Arabidopsis lipins, along with PDAT1 and SDP1, function synergistically in directing FAs toward peroxisomal b-oxidation via TAG intermediates, thereby maintaining membrane lipid homeostasis in leaves.

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Section: Pdat1 and Sdp1 Function Cooperatively In Directing Fas Towarmentioning

confidence: 86%

Arabidopsis Lipins, PDAT1 Acyltransferase, and SDP1 Triacylglycerol Lipase Synergistically Direct Fatty Acids toward β-Oxidation, Thereby Maintaining Membrane Lipid Homeostasis

et al. 2014

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“…One way in which organelles communicate and coordinate cellular activities is through the membrane contact sites (MCS), regions where the membranes of two organelles come within 10 -30 nm of one another (Elbaz and Schuldiner , 2011 ;Toulmay and Prinz , 2011 ). The MCSs are laterally differentiated subcompartments that contain the molecular tethers, by which two opposing organelles are physically interconnected as well as proteins that are specialized to mediate the inter-organelle transfer of metabolic cues and small molecules, such as ions and lipids (Figure 3 ).…”

Section: Organellar Contact Zones As Novel Microcompartmentsmentioning

confidence: 99%

“…They also include contact zones between distinct membranes (Elbaz and Schuldiner , 2011 ) or defined regions within the bacterial plasma membrane (Shapiro et al , 2009 ). Even the cytosol of bacteria and eukaryotic cells, and the lumen of the nucleus contain subcompartments, which use protein scaffolds such as the cytoskeleton, or RNA and DNA polymers as an assembly platform (Eulalio et al , 2007 ;Kaganovich et al , 2008 ;Shapiro et al , 2009 ).…”

Section: Introductionmentioning

confidence: 99%

Cellular microcompartments constitute general suborganellar functional units in cells

Holthuis

Ungermann

2013

Biological Chemistry

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All cells are compartmentalized to facilitate enzymatic reactions or cellular dynamics. In eukaryotic cells, organelles differ in their protein/lipid repertoire, luminal ion composition, pH, and redox status. In addition, organelles contain specialized subcompartments even within the same membrane or within its lumen. Moreover, the bacterial plasma membrane reveals a remarkable degree of organization, which is recapitulated in eukaryotic cells and often linked to cell signaling. Finally, protein-based compartments are also known in the bacterial and eukaryotic cytosol. As the organizing principle of such cellular subcompartments is likely similar, previous definitions like rafts, microdomains, and all kinds of ' -somes ' fall short as a general denominator to describe such suborganellar structures. Within this review, we will introduce the term cellular microcompartment as a general suborganellar functional unit and discuss its relevance to understand subcellular organization and function.

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“…The ER has been found to make close contact with other organelles (Toulmay and Prinz, 2011;Elbaz and Schuldiner, 2011). At these regions, often called membrane contact sites (MCSs), the ER membrane and a second organelle are closely apposed, typically within about 20 nm of one another.…”

Section: Introductionmentioning

confidence: 99%

“…A number of proteins have been proposed to maintain these contacts in mammalian cells (Toulmay and Prinz, 2011;Elbaz and Schuldiner, 2011). Whether similar complexes exist in yeast is not known.…”

Section: Introductionmentioning

confidence: 99%

ER-shaping proteins facilitate lipid exchange between the ER and mitochondria in S. cerevisiae

Voss

Lahiri

Young

et al. 2012

Journal of Cell Science

107

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SummaryThe endoplasmic reticulum (ER) forms a network of sheets and tubules that extends throughout the cell. Proteins required to maintain this complex structure include the reticulons, reticulon-like proteins, and dynamin-like GTPases called atlastins in mammals and Sey1p in Saccharomyces cerevisiae. Yeast cells missing these proteins have abnormal ER structure, particularly defects in the formation of ER tubules, but grow about as well as wild-type cells. We screened for mutations that cause cells that have defects in maintaining ER tubules to grow poorly. Among the genes we found were members of the ER mitochondria encounter structure (ERMES) complex that tethers the ER and mitochondria. Close contacts between the ER and mitochondria are thought to be sites where lipids are moved from the ER to mitochondria, a process that is required for mitochondrial membrane biogenesis. We show that ER to mitochondria phospholipid transfer slows significantly in cells missing both ER-shaping proteins and the ERMES complex. These cells also have altered steady-state levels of phospholipids. We found that the defect in ER to mitochondria phospholipid transfer in a strain missing ER-shaping proteins and a component of the ERMES complex was corrected by expression of a protein that artificially tethers the ER and mitochondria. Our findings indicate that ER-shaping proteins play a role in maintaining functional contacts between the ER and mitochondria and suggest that the shape of the ER at ER-mitochondria contact sites affects lipid exchange between these organelles.

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Staying in touch: the molecular era of organelle contact sites

Cited by 207 publications

References 75 publications

Arabidopsis Lipins, PDAT1 Acyltransferase, and SDP1 Triacylglycerol Lipase Synergistically Direct Fatty Acids toward β-Oxidation, Thereby Maintaining Membrane Lipid Homeostasis

Arabidopsis Lipins, PDAT1 Acyltransferase, and SDP1 Triacylglycerol Lipase Synergistically Direct Fatty Acids toward β-Oxidation, Thereby Maintaining Membrane Lipid Homeostasis

Cellular microcompartments constitute general suborganellar functional units in cells

ER-shaping proteins facilitate lipid exchange between the ER and mitochondria in S. cerevisiae

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