Single-molecule manipulation of macromolecules on GUV or SUV membranes using optical tweezers

Wang, Yukun; Kumar, Avinash; Jin, Hong; Zhang, Yongli

doi:10.1016/j.bpj.2021.11.2884

Cited by 11 publications

(6 citation statements)

References 67 publications

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“…To estimate the lipid flow properties of VPS13 and ATG2, we chose l = 20 nm (Valverde et al, 2019; Li et al . , 2020; Tunyasuvunakool et al, 2021), D = 4 µm 2 /s (Wang et al, 2021b), N = 20 (Kumar et al, 2018; Valverde et al, 2019), and k B T = 4.1 pN × nm. In the range of the membrane tension difference normalΔ σ = 0.001 - 0.1 pN/nm, we calculated the average lipid passing time τ = 0.6–0.06 s, the lipid flow rate J = 34–3,400 s −1 , and the conductance G = 3.4 × 10 4– 3.4 × 10 6 nm × pN −1 s −1 .…”

Section: Introductionmentioning

confidence: 99%

Quantitative Models of Lipid Transfer and Membrane Contact Formation

Zhang

Bian

et al. 2022

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Lipid transfer proteins (LTPs) transfer lipids between different organelles, and thus play key roles in lipid homeostasis and organelle dynamics. The lipid transfer often occurs at the membrane contact sites (MCS) where two membranes are held within 10–30 nm. While most LTPs act as a shuttle to transfer lipids, recent experiments reveal a new category of eukaryotic LTPs that may serve as a bridge to transport lipids in bulk at MCSs. However, the molecular mechanisms underlying lipid transfer and MCS formation are not well understood. Here, we first review two recent studies of extended synaptotagmin (E-Syt)-mediated membrane binding and lipid transfer using novel approaches. Then we describe mathematical models to quantify the kinetics of lipid transfer by shuttle LTPs based on a lipid exchange mechanism. We find that simple lipid mixing among membranes of similar composition and/or lipid partitioning among membranes of distinct composition can explain lipid transfer against a concentration gradient widely observed for LTPs. We predict that selective transport of lipids, but not membrane proteins, by bridge LTPs leads to osmotic membrane tension by analogy to the osmotic pressure across a semipermeable membrane. A gradient of such tension and the conventional membrane tension may drive bulk lipid flow through bridge LTPs at a speed consistent with the fast membrane expansion observed in vivo. Finally, we discuss the implications of membrane tension and lipid transfer in organelle biogenesis. Overall, the quantitative models may help clarify the mechanisms of LTP-mediated MCS formation and lipid transfer.

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Section: Introductionmentioning

confidence: 99%

Quantitative Models of Lipid Transfer and Membrane Contact Formation

Zhang

Bian

et al. 2022

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“…Mechanical changes across the artificial cell membrane are induced by pulling a membrane tether ( Figure 5 a) using optical tweezers. 53 Tethers are formed by pulling the vesicles away from a surface to which they adhere ( Figure 5 a,b). Interestingly, the fluorescently labeled subcompartments colocalize not only on the inner artificial cell surface but also within the membrane tether ( Figure 5 b).…”

Section: Resultsmentioning

confidence: 99%

“…We show that mechanical stimuli can be used to switch the artificial cell compartmentalization from a layered state to a dispersed state (Figure ). Mechanical changes across the artificial cell membrane are induced by pulling a membrane tether (Figure a) using optical tweezers . Tethers are formed by pulling the vesicles away from a surface to which they adhere (Figure a,b).…”

Section: Resultsmentioning

confidence: 99%

Dynamic Reconfiguration of Subcompartment Architectures in Artificial Cells

et al. 2022

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Artificial cells are minimal structures constructed from biomolecular building blocks designed to mimic cellular processes, behaviors, and architectures. One near-ubiquitous feature of cellular life is the spatial organization of internal content. We know from biology that organization of content (including in membrane-bound organelles) is linked to cellular functions and that this feature is dynamic: the presence, location, and degree of compartmentalization changes over time. Vesicle-based artificial cells, however, are not currently able to mimic this fundamental cellular property. Here, we describe an artificial cell design strategy that addresses this technological bottleneck. We create a series of artificial cell architectures which possess multicompartment assemblies localized either on the inner or on the outer surface of the artificial cell membrane. Exploiting liquid–liquid phase separation, we can also engineer spatially segregated regions of condensed subcompartments attached to the cell surface, aligning with coexisting membrane domains. These structures can sense changes in environmental conditions and respond by reversibly transitioning from condensed multicompartment layers on the membrane surface to a dispersed state in the cell lumen, mimicking the dynamic compartmentalization found in biological cells. Likewise, we engineer exosome-like subcompartments that can be released to the environment. We can achieve this by using two types of triggers: chemical (addition of salts) and mechanical (by pulling membrane tethers using optical traps). These approaches allow us to control the compartmentalization state of artificial cells on population and single-cell levels.

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“…Several commonly used model membranes are suitable for experimentally studying lipid flow, including unilamellar liposomes (SUVs and GUVs), supported bilayers, and free-standing bilayers [70][71][72][73]. For example, to examine lipid transfer across two apposed membranes, one can potentially bring two liposomes (or a liposome and a supported bilayer) containing reconstituted LTPs into proximity.…”

Section: Methods To Test Lipid Osmosis and Lipid Transfermentioning

confidence: 99%

Lipid osmosis, membrane tension, and other mechanochemical driving forces of lipid flow

Zhang,

Lin

2024

Preprint

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Nonvesicular lipid transport among different membranes or membrane domains plays crucial roles in processes such as lipid homeostasis and organelle biogenesis. However, the forces that drive such lipid transport are not well understood. We propose that lipids tend to flow towards the membrane area with a higher membrane protein density in a process termedlipid osmosis. This process lowers the membrane tension in the area when the lipid flow reaches equilibrium. We examine the thermodynamic basis and experimental evidence of lipid osmosis and the correspondingosmotic membrane tension. We predict that lipid osmosis can drive lipid flows between different membrane regions through lipid transfer proteins, scramblases, or other similar barriers that selectively pass lipids but not membrane proteins. We also speculate on the biological functions of lipid osmosis. Finally, we explore other driving forces for lipid transfer and describe potential methods and systems to further test our theory.

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Single-molecule manipulation of macromolecules on GUV or SUV membranes using optical tweezers

Cited by 11 publications

References 67 publications

Quantitative Models of Lipid Transfer and Membrane Contact Formation

Quantitative Models of Lipid Transfer and Membrane Contact Formation

Dynamic Reconfiguration of Subcompartment Architectures in Artificial Cells

Lipid osmosis, membrane tension, and other mechanochemical driving forces of lipid flow

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