Ether lipid
![](https://upload.wikimedia.org/wikipedia/commons/thumb/9/98/Ether_lipid.svg/220px-Ether_lipid.svg.png)
![](https://upload.wikimedia.org/wikipedia/commons/thumb/7/72/Plasmalogen.png/220px-Plasmalogen.png)
![](https://upload.wikimedia.org/wikipedia/commons/thumb/5/55/Platelet-activating_factor.svg/220px-Platelet-activating_factor.svg.png)
Inbiochemistry,anether lipidrefers to anylipidin which the lipid "tail" group is attached to theglycerolbackbone via anether bondat any position. In contrast, conventionalglycerophospholipidsandtriglyceridesare triesters.[1]Structural types include:
- Ether phospholipids:phospholipids are known to have ether-linked "tails" instead of the usual ester linkage.[1]
- Ether on sn-1, ester on sn-2:"ether lipids" in the context of bacteria and eukaryotes refer to this class of lipids. Compared to the usual1,2-diacyl-sn-glycerol(DAG), the sn-1 linkage is replaced with an ester bond.[1][2][3]
Based on whether the sn-1 lipid is unsaturated next to the ether linkage, they can be further divided intoalkenyl-acylphospholipids( "plasmenylphospholipid", 1-0-alk-1’-enyl-2-acyl-sn-glycerol) andalkyl-acylphospholipids( "plasmanylphospholipid" ). This class of lipids have important roles in human cell signaling and structure.[4]
- Ether analogues of triglycerides:1-alkyldiacyl-sn-glycerols (alkyldiacylglycerols) are found in significant proportions in marine animals.[5]
- Other ether lipids:a number of other lipids not belonging to any of the classes above contain the ether linkage. For example,seminolipid,a vital part of the testes and sperm cells, has a ether linkage.[1]
The term "plasmalogen"can refer to any ether lipid with avinyl etherlinkage, i.e. ones with a carbon-carbondouble bondnext to the ether linkage. Without specification it generally refers to alkenyl-acylphospholipids, but "neutral plasmalogens" (alkenyldiacylglycerols) and "diplasmalogens" (dialkenylphospholipids) also exist.[1]The prototypical plasmalogen isplatelet-activating factor.[7]
In eukaryotes
[edit]Biosynthesis
[edit]The formation of the ether bond in mammals requires two enzymes,dihydroxyacetonephosphate acyltransferase(DHAPAT) andalkyldihydroxyacetonephosphate synthase(ADAPS), that reside in theperoxisome.[8]Accordingly, peroxisomal defects often lead to impairment of ether-lipid production.
Monoalkylglycerol ethers (MAGEs) are also generated from 2-acetyl MAGEs (precursors of PAF) byKIAA1363.
Functions
[edit]Structural
[edit]Plasmalogens as well as some 1-O-alkyl lipids are ubiquitous and sometimes major parts of thecell membranesinmammals.[9]Theglycosylphosphatidylinositolanchor of mammalian proteins generally consist of an 1-O-alkyl lipid.[1]
Second messenger
[edit]Differences between thecatabolismof ether glycerophospholipids by specificphospholipasesenzymesmight be involved in the generation of lipidsecond messenger systemssuch asprostaglandinsandarachidonic acidthat are important in signal transduction.[10]Ether lipids can also act directly in cell signaling, as theplatelet-activating factoris an ether lipid signaling molecule that is involved inleukocytefunction in the mammalianimmune system.[11]
Antioxidant
[edit]Another possible function of the plasmalogen ether lipids is asantioxidants,as protective effects againstoxidative stresshave been demonstrated incell cultureand these lipids might therefore play a role in serumlipoproteinmetabolism.[12]This antioxidant activity comes from the enol ether double bond being targeted by a variety ofreactive oxygen species.[13]
Synthetic ether lipid analogs
[edit]Synthetic ether lipid analogs havecytostatic and cytotoxicproperties, probably by disrupting membrane structure and acting asinhibitorsof enzymes within signal transmission pathways, such asprotein kinase Candphospholipase C.
A toxic ether lipid analoguemiltefosinehas recently been introduced as an oral treatment for the tropical diseaseleishmaniasis,which is caused byleishmania,aprotozoalparasite with a particularly high ether lipid content in its membranes.[14]
In archaea
[edit]The cell membrane ofarchaeaconsist mostly of ether phospholipids. These lipids have a flipped chirality compared to bacterial and eukaryotic membranes, a conundrum known as the "lipid divide".The" tail "groups are also not simply n-alkyl groups, but highly methylated chains made up of saturatedisoprenoidunits (e.g.phytanyl).[15]
Among different groups of archaea, diverse modifications on the basicarchaeolbackbone have emerged.
- The two tails can be linked together, forming a macrocyclic lipid.[15]
- Bipolar macrocyclic tetraether lipids (caldarchaeol), with two glycerol units connected by two C40"tail" chains, formcovalentlylinked 'bilayers'.[16][15]
- Some such covelant bilayers feature crosslinks between the two chains, giving an H-shaped molecule.[15]
- Crenarchaeolis a tetraether backbone with cyclopentane and cyclohexane rings on the cross-linked "tail" s.[15]
- Some lipids replace the glycerol backbone with four-carbon polyols (tetriols).[15]
In bacteria
[edit]Ether phospholipids are major parts of the cell membrane in anaerobic bacteria.[1]These lipids can be variously 1-O-alkyl, 2-O-alkyl, or 1,2-O-dialkyl. Some groups have, like archaea, evolved tetraether lipids.[17]
In prokaryotes
[edit]Some ether lipids found in marine animals are S-batyl alcohol,S-chimyl alcohol,and S-selachyl alcohol.
See also
[edit]References
[edit]- ^abcdefgChristie W."Ether lipids - glyceryl ethers, plasmalogens, aldehydes, structure, biochemistry, composition and analysis".lipidmaps.org.
- ^Dean JM, Lodhi IJ (February 2018)."Structural and functional roles of ether lipids".Protein & Cell.9(2): 196–206.doi:10.1007/s13238-017-0423-5.PMC5818364.PMID28523433.
- ^Ford DA, Gross RW (July 1990)."Differential metabolism of diradyl glycerol molecular subclasses and molecular species by rabbit brain diglyceride kinase".The Journal of Biological Chemistry.265(21): 12280–6.doi:10.1016/S0021-9258(19)38342-5.PMID2165056.S2CID1042240.
- ^Dean, JM; Lodhi, IJ (February 2018)."Structural and functional roles of ether lipids".Protein & Cell.9(2): 196–206.doi:10.1007/s13238-017-0423-5.PMC5818364.PMID28523433.
- ^abVillanueva, Laura; von Meijenfeldt, F. A. Bastiaan; Westbye, Alexander B.; Yadav, Subhash; Hopmans, Ellen C.; Dutilh, Bas E.; Damsté, Jaap S. Sinninghe (January 2021)."Bridging the membrane lipid divide: bacteria of the FCB group superphylum have the potential to synthesize archaeal ether lipids".The ISME Journal.15(1): 168–182.Bibcode:2021ISMEJ..15..168V.doi:10.1038/s41396-020-00772-2.PMC7852524.PMID32929208.
- ^"Di- and Tetra-Alkyl Ether Lipids of the Archaea".lipidmaps.org.
- ^Watson RR, De Meester F, eds. (2014).Omega 3 fatty acids in brain and neurological health.Elsevier Academic Press.doi:10.1016/C2012-0-06006-1.ISBN978-0-12-410527-0.
- ^Hajra AK (1995). "Glycerolipid biosynthesis in peroxisomes (microbodies)".Progress in Lipid Research.34(4): 343–64.doi:10.1016/0163-7827(95)00013-5.PMID8685243.
- ^Paltauf F (December 1994). "Ether lipids in biomembranes".Chemistry and Physics of Lipids.74(2): 101–39.doi:10.1016/0009-3084(94)90054-X.PMID7859340.
- ^Spector AA, Yorek MA (September 1985)."Membrane lipid composition and cellular function".Journal of Lipid Research.26(9): 1015–35.doi:10.1016/S0022-2275(20)34276-0.PMID3906008.Archived fromthe originalon 2008-10-10.Retrieved2007-03-08.
- ^Demopoulos CA, Pinckard RN, Hanahan DJ (October 1979)."Platelet-activating factor. Evidence for 1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine as the active component (a new class of lipid chemical mediators)".The Journal of Biological Chemistry.254(19): 9355–8.doi:10.1016/S0021-9258(19)83523-8.PMID489536.
- ^Brosche T, Platt D (August 1998). "The biological significance of plasmalogens in defense against oxidative damage".Experimental Gerontology.33(5): 363–9.doi:10.1016/S0531-5565(98)00014-X.PMID9762517.S2CID20977817.
- ^Engelmann B (February 2004). "Plasmalogens: targets for oxidants and major lipophilic antioxidants".Biochemical Society Transactions.32(Pt 1): 147–50.doi:10.1042/BST0320147.PMID14748736.
- ^Lux H, Heise N, Klenner T, Hart D, Opperdoes FR (November 2000). "Ether--lipid (alkyl-phospholipid) metabolism and the mechanism of action of ether--lipid analogues in Leishmania".Molecular and Biochemical Parasitology.111(1): 1–14.doi:10.1016/S0166-6851(00)00278-4.PMID11087912.
- ^abcdefCaforio, Antonella; Driessen, Arnold J.M. (2017)."Archaeal phospholipids: Structural properties and biosynthesis"(PDF).Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids.1862(11): 1325–1339.doi:10.1016/j.bbalip.2016.12.006.PMID28007654.S2CID27154462.
- ^Koga Y, Morii H (November 2005)."Recent advances in structural research on ether lipids from archaea including comparative and physiological aspects".Bioscience, Biotechnology, and Biochemistry.69(11): 2019–34.doi:10.1271/bbb.69.2019.PMID16306681.
- ^Grossi, V; Mollex, D; Vinçon-Laugier, A; Hakil, F; Pacton, M; Cravo-Laureau, C (1 May 2015)."Mono- and dialkyl glycerol ether lipids in anaerobic bacteria: biosynthetic insights from the mesophilic sulfate reducer Desulfatibacillum alkenivorans PF2803T".Applied and Environmental Microbiology.81(9): 3157–68.Bibcode:2015ApEnM..81.3157G.doi:10.1128/AEM.03794-14.PMC4393425.PMID25724965.
External links
[edit]- Ether+phospholipidsat the U.S. National Library of MedicineMedical Subject Headings(MeSH)