Biosynthesis of the glycolipid anchor of lipophosphoglycan and the structurally related glycoinositolphospholipids from <i>Leishmania major</i>

Proudfoot, Lorna; Schneider, Pascal; Ferguson, Michael A. J.; McConville, Malcolm J.

doi:10.1042/bj3080045

Cited by 42 publications

(45 citation statements)

References 34 publications

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“…1). The decrease in the rate of synthesis of LPG was matched by a decrease in the size of the LPG steady-state pool, consistent with previous studies showing that LPG is rapidly shed from the plasma membrane (37). However, the steady-state pools of the GIPLs either remained unchanged in the promastigote stages or increased 3-fold in LA.…”

Section: Figsupporting

confidence: 78%

“…However, the steady-state pools of the GIPLs either remained unchanged in the promastigote stages or increased 3-fold in LA. The major GIPL species contain two fatty chains, rather than the single alkyl chain in the LPG anchor, which may increase their stability in the plasma membrane (37). As these glycolipids would still be diluted during cell division, their unchanging pool size indicates that the growth rate of amastigotes in mature lesions must be comparatively slow.…”

Section: Figmentioning

confidence: 99%

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Evidence That Intracellular β1-2 Mannan Is a Virulence Factor in Leishmania Parasites

Ralton¹,

Naderer²,

Piraino

et al. 2003

Journal of Biological Chemistry

108

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The protozoan parasite Leishmania mexicana proliferates within macrophage phagolysosomes in the mammalian host. In this study we provide evidence that a novel class of intracellular ␤1-2 mannan oligosaccharides is important for parasite survival in host macrophages. Mannan (degree of polymerization 4 -40) is expressed at low levels in non-pathogenic promastigote stages but constitutes 80 and 90% of the cellular carbohydrate in the two developmental stages that infect macrophages, non-dividing promastigotes, and lesionderived amastigotes, respectively. Mannan is catabolized when parasites are starved of glucose, suggesting a reserve function, and developmental stages having low mannan levels or L. mexicana GDPMP mutants lacking all mannose molecules are highly sensitive to glucose starvation. Environmental stresses, such as mild heat shock or the heat shock protein-90 inhibitor, geldanamycin, that trigger the differentiation of promastigotes to amastigotes, result in a 10 -25-fold increase in mannan levels. Developmental stages with low mannan levels or L. mexicana mutants lacking mannan do not survive heat shock and are unable to differentiate to amastigotes or infect macrophages in vitro. In contrast, a L. mexicana mutant deficient only in components of the mannose-rich surface glycocalyx differentiates normally and infects macrophages in vitro. Collectively, these data provide strong evidence that mannan accumulation is important for parasite differentiation and survival in macrophages.Leishmania species are sandfly-transmitted protozoan parasites that cause a number of human diseases, ranging from self-healing cutaneous lesions to fatal visceral infections, afflicting more than 12 million people worldwide (www.who.int/ inf-fs/en/fact116.html). These parasites develop within the midgut of the sandfly vector, initially as rapidly dividing procyclic promastigotes and subsequently as non-dividing, but highly virulent, metacyclic promastigotes. Upon transmission to the mammalian host, metacyclic promastigotes invade macrophages and differentiate to the amastigote stage that proliferates within the phagolysosomal compartment. Parasite survival within the highly acidic and hydrolytic environment of the phagolysosome is likely to involve the induction of a number of biochemical processes, such as the activation of a heat shock response (1) and the stage-specific expression of specific nutrient transporters (2).It has recently been reported that one or more mannose (Man)-containing molecules are essential for L. mexicana survival in macrophages and infectivity in animals (3, 4). Specifically, targeted deletion of genes involved in GDP-Man synthesis, such as phosphomannomutase and GDP-Man pyrophosphorylase (GDP-MP), 1 did not affect parasite growth in rich culture medium but completely attenuated infectivity in macrophages and in highly susceptible BALB/c mice (3). The GDP-Man-negative mutant, GDPMP, was shown to be deficient in a range of cell surface and secreted mannose-containing molecules, including several abunda...

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Section: Figsupporting

confidence: 78%

Section: Figmentioning

confidence: 99%

Evidence That Intracellular β1-2 Mannan Is a Virulence Factor in Leishmania Parasites

Ralton¹,

Naderer²,

Piraino

et al. 2003

Journal of Biological Chemistry

108

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“…h-'/cell. This figure, although substantial, is only about 7% of the activity that would be required by L. major to turn over approximately half of its 3 -5 X lo6 copies of procyclic promastigote lipophosphoglycan (containing an average of 16 Man-P residues [6]) in an hour [29]. A similarly low yield has also been reported for the pgalactosyltransferase activity that modifies the phosphosaccharide repeats of L. mujor lipophosphoglycan [23].…”

Section: Discussionmentioning

confidence: 89%

Synthetic Phospho‐Oligosaccharide Fragments of Lipophosphoglycan as Acceptors for Leishmania majorα‐d‐Mannosylphosphate Transferase

Brown¹,

Millar²,

Masterson³

et al. 1996

European Journal of Biochemistry

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Protozoan parasites of the genus Leishmania synthesise lipophosphoglycans, phosphoglycans and proteophosphoglycans that contain phosphosaccharide-repeat units of . In this study, a GDP-Man-dependent a-mannosylphosphate-transferase activity was detected in washed Leishmania major membranes using synthetic phospho-oligosaccharide fragments of lipophosphoglycan as acceptor substrates. The divalent-cation-dependent a-mannosylphosphate-transferase activity had an apparent K,, for GDP-Man of about 15-20 pM and a pH optimum of 7.0. The activity showed a requirement for a nonreducing terminal pGal residue and for one or more phosphodiester units preceding the acceptor site. Based on these results, the activity may be defined as a GDP-Man: Galpl-4Manal-P-R a-mannosylphosphate-transferase. This acceptor specificity is consistent with a role for the a-mannosylphosphate transferase in the elongation of phosphosaccharide-repeat domains of Leishmania glycoconjugates rather than in the priming of these domains. An identical or similar activity must exist in the amastigote forms of the Leishmania that produce and secrete proteophosphoglycan material and the activity therefore represents a feasible target for the development of chemotherapeutics.Keywords: lipophosphoglycan; proteophosphoglycan; Leishmania; phospho-oligosaccharide biosynthesis.The sandfly-transmitted protozoan parasites of the genus Leishmania cause a variety of diseases [I], ranging from mild cutaneous lesions to lethal visceral infections, throughout the tropics and subtropics. The parasites divide in the midgut of the insect vector as flagellated procyclic promastigote forms that, following transformation into non-dividing metacyclic promastigote forms, make their way to the mouth parts of the vector. The metacyclic promastigotes that are injected into the mammalian host with the insect saliva rapidly attach to and invade the host macrophages. Within the macrophage phagolysosome, the metacyclic promastigotes differentiate into small round amastigote forms that divide until the host cell is ruptured. The infection is then propagated by amastigote invasion of other macrophages.The Leishmania produce unusual glycoconjugates that contain phosphosaccharide-repeat units of , [2]. Such molecules have been found in both the promastigote and amastigote stages of all species of the Leishmania analysed so far and include lipophosphoglycan, secreted phosphoglycan and secreted proteophosphoglycan. Galpl-4( t R'-2)Manal-P-In-6Galal -6Galal-3GalfP1-31 2 Glc a1 -P-6)Manal-3Manal-4GlcNal-6Ins-1 -P-3(sn-1 -0-alky lglycerol). Species-and stage-specific differences are seen in (a) the structure of the non-reducing terminal oligosaccharide, ( b) the nature of the saccharides (R and R') that can substitute the basic phosphosaccharide repeat, (c) the average number (n) of repeats and (d) the proportion of structures containing a Glcal-P substituent on the glycoinositol-phospholipid core. For a comprehensive review of lipophosphoglycan structures see [7].The secreted phosphoglycans o...

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“…The presence of lipid on a small proportion of CM-AGPs, however, suggests that AGPs with GPI lipid anchors are amphipathic enough to sometimes release from the plasma membrane by stochastic biophysical partitioning, as reported for the GPI-anchored lipophosphoglycan of L. major (35).…”

Section: Discussionmentioning

confidence: 94%

“…A solution to this dilemma was suggested by the literature on the protozoan parasite Leishmania major, the plasma membrane of which contains both a lipophosphoglycan with GPI lipid anchor and a structurally related glycoinositolphospholipid. Proudfoot et al (35) found that appreciable shedding of lipophosphoglycan from the plasma membrane occurred as a stochastic biophysical event in which the highly polar polysaccharide portion of the lipophosphoglycan occasionally pulled the lipid anchor out of the membrane into the aqueous medium. No shedding of glycoinositolphospholipid from the membrane occurred, however, because its oligosaccharide head group, although also polar, was too small to pull the lipid anchor out of the membrane.…”

Section: Resultsmentioning

confidence: 99%

Presence of a Glycosylphosphatidylinositol Lipid Anchor on Rose Arabinogalactan Proteins

Svetek¹,

Yadav

Nothnagel

1999

Journal of Biological Chemistry

135

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Arabinogalactan proteins constitute a class of plant cell surface proteoglycans with widespread occurrence and suggested functions in various aspects of plant growth and development, including cell proliferation, expansion, marking, and death. Previous investigations of subcellular fractions from suspension-cultured cells of "Paul's Scarlet" rose (Rosa sp.) have revealed extensive structural similarity between some soluble arabinogalactan proteins from the cell wall space and some plasma membrane-associated arabinogalactan proteins, thus inspiring the present investigation of the mechanism through which these inherently water-soluble molecules are held on the plasma membrane. Several lines of evidence gained through a combination of methods including reversed-phase chromatography, treatment with phosphatidylinositol-specific phospholipase C, and chemical structural analysis now show that some rose arabinogalactan proteins carry a ceramide class glycosylphosphatidylinositol lipid anchor. The predominant form of the ceramide is composed of tetracosanoic acid and 4-hydroxysphinganine. Plasma membrane vesicles readily shed arabinogalactan proteins by an inherent mechanism that appears to involve a phospholipase. This finding has significance toward understanding the biosynthesis, localization, and function of arabinogalactan proteins and toward stimulating other studies that may expand the currently very short list of higher plant proteins found to carry such membrane lipid anchors.

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Biosynthesis of the glycolipid anchor of lipophosphoglycan and the structurally related glycoinositolphospholipids from Leishmania major

Cited by 42 publications

References 34 publications

Evidence That Intracellular β1-2 Mannan Is a Virulence Factor in Leishmania Parasites

Evidence That Intracellular β1-2 Mannan Is a Virulence Factor in Leishmania Parasites

Synthetic Phospho‐Oligosaccharide Fragments of Lipophosphoglycan as Acceptors for Leishmania majorα‐d‐Mannosylphosphate Transferase

Presence of a Glycosylphosphatidylinositol Lipid Anchor on Rose Arabinogalactan Proteins

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