Synthesis and Structural Characterization of Three Unique <i>Helicobacter pylori</i> α<i>‐</i>Cholesteryl Phosphatidyl Glucosides

Nguyen, Huy Quoc; Davis, Ryan A.; Gervay‐Hague, Jacquelyn

doi:10.1002/ange.201406529

Cited by 5 publications

(3 citation statements)

References 25 publications

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“…When the phospholipid was activated as a pentavalent phosphoramide, a dimerized byproduct was obtained from the unreacted phospholipid, and the purification step was laborious because of their high polarity and instability. 20,21 Thus, a phosphoramidite (2) bearing a Bn group and DAG was synthesized from phosphorus trichloride, 22,23 which was easily purified by a silica gel column and could be stored for several months at −20 °C.…”

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confidence: 99%

Syntheses and Activities of the Functional Structures of a Glycolipid Essential for Membrane Protein Integration

et al. 2018

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MPIase is the first known glycolipid that is essential for membrane protein integration in the inner membrane of E. coli. Since the amount of natural MPIase available for analysis is limited and it contains structural heterogeneity, precisely designed synthetic derivatives are promising tools for further elucidation of its membrane protein integration mechanism. Thus, we synthesized the minimal unit of MPIase, a trisaccharyl pyrophospholipid termed mini-MPIase-3, and its derivatives. Integration assays revealed that the chemically synthesized trisaccharyl pyrophospholipid possesses significant activity, indicating that it includes the essential structure for membrane integration. Structure-activity relationship studies demonstrated that the number of trisaccharide units and the 6- O-acetyl group on N-acetylglucosamine contribute to efficient integration. Furthermore, anchoring in the membrane by a lipid moiety was essential for the integration. However, the addition of phosphorylated glycans devoid of the lipid moiety in the assay solution modulated the integration activity of MPIase embedded in liposomes, suggesting an interaction between phosphorylated glycans and substrate proteins in aqueous solutions. The prevention of protein aggregation required the 6- O-acetyl group on N-acetylglucosamine, a phosphate group at the reducing end of the glycan, and a long glycan chain. Taken together, we verified the mechanism of the initial step of the translocon-independent pathway in which a membrane protein is captured by a glycan of MPIase, which maintains its structure to be competent for integration, and then MPIase integrates it into the membrane by hydrophobic interactions with membrane lipids.

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confidence: 99%

Syntheses and Activities of the Functional Structures of a Glycolipid Essential for Membrane Protein Integration

et al. 2018

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“…Gervay-Hague and co-workers established a novel one-pot glycosylation method employing per-O-TMS glycosyl iodides with fully functionalized diglyceride and ceramide as well as cholesterol as acceptors for accessing α or β-glycosides such as α-GalCer KRN-7000, 427 BBGL-1, 428 and others (Figure 11). 256,429 Their methodology cleverly incorporates the arming effect of the TMS group and its acid lability by carrying out the stereoselective coupling of per-O-TMS glycosyl iodides in the presence of either TBAI or AgCO 3 to achieve α or β selectivity, respectively, and the immediate removal of TMS ethers in the same vessel by using Dowex.…”

Section: Chemical Reviewsmentioning

confidence: 99%

“One-Pot” Protection, Glycosylation, and Protection–Glycosylation Strategies of Carbohydrates

et al. 2018

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Carbohydrates, which are ubiquitously distributed throughout the three domains of life, play significant roles in a variety of vital biological processes. Access to unique and homogeneous carbohydrate materials is important to understand their physical properties, biological functions, and disease-related features. It is difficult to isolate carbohydrates in acceptable purity and amounts from natural sources. Therefore, complex saccharides with well-defined structures are often most conviently accessed through chemical syntheses. Two major hurdles, regioselective protection and stereoselective glycosylation, are faced by carbohydrate chemists in synthesizing these highly complicated molecules. Over the past few years, there has been a radical change in tackling these problems and speeding up the synthesis of oligosaccharides. This is largely due to the development of one-pot protection, one-pot glycosylation, and one-pot protection-glycosylation protocols and streamlined approaches to orthogonally protected building blocks, including those from rare sugars, that can be used in glycan coupling. In addition, new automated strategies for oligosaccharide syntheses have been reported not only for program-controlled assembly on solid support but also by the stepwise glycosylation in solution phase. As a result, various sugar molecules with highly complex, large structures could be successfully synthesized. To summarize these recent advances, this review describes the methodologies for one-pot protection and their one-pot glycosylation into the complex glycans and the chronological developments associated with automated syntheses of oligosaccharides.

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“…S1). Tubulation may be exacerbated in our experiments because the constituent lipids likely have conical shapes and because the lipid mixtures do not include free sterols, which can mitigate membrane asymmetries via flip flop (46). To address this problem, we applied a small osmotic pressure difference sufficient to prevent most tubulation (100 mM sucrose inside, 80 mM outside).…”

Section: Methodsmentioning

confidence: 99%

Sterol-lipids enable large-scale, liquid-liquid phase separation in bilayer membranes of only 2 components

Wilson,

Nguyen,

Gervay-Hague

et al. 2024

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Despite longstanding excitement and progress toward understanding liquid-liquid phase separation in natural and artificial membranes, fundamental questions have persisted about which molecules are required for this phenomenon. Except in extraordinary circumstances, the smallest number of components that has produced large-scale, liquid-liquid phase separation in bilayers has stubbornly remained at three: a sterol, a phospholipid with ordered chains, and a phospholipid with disordered chains. This requirement of three components is puzzling for two reasons: (1) the Gibbs Phase Rule states that only two components are necessary, and (2) only two components are required for liquid-liquid phase separation in lipid monolayers, which resemble half of a bilayer. Inspired by reports that sterols interact closely with lipids with ordered chains, we tested whether phase separation would occur in bilayers in which a sterol and lipid were replaced by a single, joined sterol-lipid. By evaluating a panel of sterol-lipids, we discovered a minimal bilayer of only two components (PChemsPC and diPhyPC) that demixes into micron-scale, liquid phases. In this system, the sterol-lipid behaves as a 3:1 ratio of cholesterol to phospholipid. Our system gives the computation and theory community a two-component membrane that maps directly onto simplified theories and that can be used to validate simulation force fields. It suggests a new role for sterol-lipids in nature, and it gives experimental communities a membrane in which tie-lines (and, therefore, the lipid composition of each phase) are easily determined and will be consistent across multiple laboratories.Significance StatementA wide diversity of bilayer membranes, from those with hundreds of lipids (e.g., vacuoles of living yeast cells) to those with very few (e.g., artificial vesicles) phase separate into micron-scale liquid domains. The number of components required for liquid-liquid phase separation has been perplexing: only two should be necessary, but more are required except in extraordinary circumstances. What minimal set of molecular characteristics leads to liquid-liquid phase separation in bilayer membranes? This question inspired us to search for single, joined “sterol-lipid” molecules to replace both a sterol and a phospholipid in membranes undergoing liquid-liquid phase separation. By producing phase-separating membranes with only two components, we mitigate experimental challenges in determining tie-lines and in maintaining constant chemical potentials of lipids.

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Synthesis and Structural Characterization of Three Unique Helicobacter pylori α‐Cholesteryl Phosphatidyl Glucosides

Cited by 5 publications

References 25 publications

Syntheses and Activities of the Functional Structures of a Glycolipid Essential for Membrane Protein Integration

Syntheses and Activities of the Functional Structures of a Glycolipid Essential for Membrane Protein Integration

“One-Pot” Protection, Glycosylation, and Protection–Glycosylation Strategies of Carbohydrates

Sterol-lipids enable large-scale, liquid-liquid phase separation in bilayer membranes of only 2 components

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