Tuning ubiquinone position in biomimetic monolayer membranes

Hoyo, Javier; Guaus, E.; Torrent‐Burgués, J.

doi:10.1140/epje/i2017-11552-2

Cited by 8 publications

(7 citation statements)

References 58 publications

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“…These discrepancies may be due to the slightly soluble nature of UQ-2, differences in the composition of the subphase, and even stirring of the subphase. Pure films of DPPC and DPPE were in line with the literature (Patterson et al, 2016;Hoyo et al, 2017), with DPPC exhibiting its signature gas-liquid transition between 0 and 5 mN/m and its liquid-liquid condensed transition from 5 to 10 mN/m of surface pressure. The gas-liquid transition disappears upon the addition of UQ-2.…”

Section: Compression Isotherms Of Pure and Mixed Monolayerssupporting

confidence: 84%

“…Our value was obtained by taking the second derivative of area per molecule with respect to surface pressure, with the lowest point representing the collapse pressure. Reported literature values varied widely, with some as high as 35 mN/m and others reporting that UQ-2 dissolved into the subphase ( Quinn and Esfahani, 1980 ; Bernard et al, 2000 ; Hoyo et al, 2017 ). These discrepancies may be due to the slightly soluble nature of UQ-2, differences in the composition of the subphase, and even stirring of the subphase.…”

Section: Resultsmentioning

confidence: 99%

“…“Swimming” lipoquinones are associated with the phospholipid headgroups, and “diving” are found near the midplane. A few computational and experimental studies determined UQ and various analogs are stabilized in the swimming position ( Soderhall and Laaksonen, 2001 ; Hoyo et al, 2017 ). A recent computational study determined the lipoquinone position depends on the local protein content of the membrane ( Singharoy et al, 2020 ).…”

Section: Introductionmentioning

confidence: 99%

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Electron Transport Lipids Fold Within Membrane-Like Interfaces

et al. 2022

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Lipoquinones, such as ubiquinones (UQ) and menaquinones (MK), function as essential lipid components of the electron transport system (ETS) by shuttling electrons and protons to facilitate the production of ATP in eukaryotes and prokaryotes. Lipoquinone function in membrane systems has been widely studied, but the exact location and conformation within membranes remains controversial. Lipoquinones, such as Coenzyme Q (UQ-10), are generally depicted simply as “Q” in life science diagrams or in extended conformations in primary literature even though specific conformations are important for function in the ETS. In this study, our goal was to determine the location, orientation, and conformation of UQ-2, a truncated analog of UQ-10, in model membrane systems and to compare our results to previously studied MK-2. Herein, we first carried out a six-step synthesis to yield UQ-2 and then demonstrated that UQ-2 adopts a folded conformation in organic solvents using 1H-1H 2D NOESY and ROESY NMR spectroscopic studies. Similarly, using 1H-1H 2D NOESY NMR spectroscopic studies, UQ-2 was found to adopt a folded, U-shaped conformation within the interface of an AOT reverse micelle model membrane system. UQ-2 was located slightly closer to the surfactant-water interface compared to the more hydrophobic MK-2. In addition, Langmuir monolayer studies determined UQ-2 resided within the monolayer water-phospholipid interface causing expansion, whereas MK-2 was more likely to be compressed out and reside within the phospholipid tails. All together these results support the model that lipoquinones fold regardless of the headgroup structure but that the polarity of the headgroup influences lipoquinone location within the membrane interface. These results have implications regarding the redox activity near the interface as quinone vs. quinol forms may facilitate locomotion of lipoquinones within the membrane. The location, orientation, and conformation of lipoquinones are critical for their function in generating cellular energy within membrane ETS, and the studies described herein shed light on the behavior of lipoquinones within membrane-like environments.

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Section: Compression Isotherms Of Pure and Mixed Monolayerssupporting

confidence: 84%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electron Transport Lipids Fold Within Membrane-Like Interfaces

et al. 2022

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“…However, the 50:50 and 75:25 DPPE:MK-4 films exhibited a liquid condensed phase from 1 mN/m to 17 mN/m. The liquid condensed phases seen in the DPPE:MK-2 and DPPE:MK-4 mixed films indicate an expansive effect, which is observed in literature with UQ [34,35]. This expansion at lower surface pressures may be due to aggregation and/or conformation of the MK homologues.…”

Section: Compression Isotherms Of Normalized Mixed Mk and Dppc Or Dppe Filmssupporting

confidence: 64%

Interactions of Truncated Menaquinones in Lipid Monolayers and Bilayers

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Koehn

Pereira

et al. 2021

IJMS

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Menaquinones (MK) are hydrophobic molecules that consist of a naphthoquinone headgroup and a repeating isoprenyl side chain and are cofactors used in bacterial electron transport systems to generate cellular energy. We have previously demonstrated that the folded conformation of truncated MK homologues, MK-1 and MK-2, in both solution and reverse micelle microemulsions depended on environment. There is little information on how MKs associate with phospholipids in a model membrane system and how MKs affect phospholipid organization. In this manuscript, we used a combination of Langmuir monolayer studies and molecular dynamics (MD) simulations to probe these questions on truncated MK homologues, MK-1 through MK-4 within a model membrane. We observed that truncated MKs reside farther away from the interfacial water than ubiquinones are are located closer to the phospholipid tails. We also observed that phospholipid packing does not change at physiological pressure in the presence of truncated MKs, though a difference in phospholipid packing has been observed in the presence of ubiquinones. We found through MD simulations that for truncated MKs, the folded conformation varied, but MKs location and association with the bilayer remained unchanged at physiological conditions regardless of side chain length. Combined, this manuscript provides fundamental information, both experimental and computational, on the location, association, and conformation of truncated MK homologues in model membrane environments relevant to bacterial energy production.

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“…Subsequently, seven consecutive chemical reactions modify the head group to yield UQ (Figure 1A). Hydrophobic polyprenylated intermediates of the UQ biosynthetic pathway are predicted to be embedded within the lipid bilayer (Stefely and Pagliarini, 2017), with the head groups near the glycerol backbone of the membrane phospholipids, and the isoprenoid tail inserted between their acyl chains (Galassi and Arantes, 2015;Hoyo et al, 2017;Wollstein et al, 2015). In contrast, the decarboxylase, methyltransferases and hydroxylases of the UQ biosynthetic pathway contain no transmembrane domains and are predicted to be soluble.…”

Section: Introductionmentioning

confidence: 99%