Modulation of non-bilayer lipid phases and the structure and functions of thylakoid membranes: effects on the water-soluble enzyme violaxanthin de-epoxidase
Abstract:the role of non-bilayer lipids and non-lamellar lipid phases in biological membranes is an enigmatic problem of membrane biology. non-bilayer lipids are present in large amounts in all membranes; in energy-converting membranes they constitute about half of their total lipid content-yet their functional state is a bilayer. in vitro experiments revealed that the functioning of the water-soluble violaxanthin de-epoxidase (VDE) enzyme of plant thylakoids requires the presence of a non-bilayer lipid phase. 31 p-nMR… Show more
“…Thylakoid membranes are always close to HII phase transition and, as HII phases emerge, they must be controlled to avoid damage, which involves the function of sHSPs (Tsvetkova et al, 2002). HII phases are however key to chloroplast heat acclimation because when they emerge under stress, they recruit and activate the xanthophyll cycle enzyme, violaxanthin deepoxidase (VDE) (Dlouhý et al, 2020). VDE synthesizes zeaxanthin which quenches excess excitation energy and enhances membrane F I G U R E 3 Sensing and signalling of heat stress at the chloroplast.…”
Section: Adjustment Of Membrane Fluidity Through Changes In Membranementioning
Plants alter their morphology and cellular homeostasis to promote resilience under a variety of heat regimes. Molecular processes that underlie these responses have been intensively studied and found to encompass diverse mechanisms operating across a broad range of cellular components, timescales and temperatures. This review explores recent progress throughout this landscape with a particular focus on thermosensing in the model plant Arabidopsis. Direct temperature sensors include the photosensors phytochrome B and phototropin, the clock component ELF3 and an RNA switch. In addition, there are heat‐regulated processes mediated by ion channels, lipids and lipid‐modifying enzymes, taking place at the plasma membrane and the chloroplast. In some cases, the mechanism of temperature perception is well understood but in others, this remains an open question. Potential novel thermosensing mechanisms are based on lipid and liquid–liquid phase separation. Finally, future research directions of high temperature perception and signalling pathways are discussed.
“…Thylakoid membranes are always close to HII phase transition and, as HII phases emerge, they must be controlled to avoid damage, which involves the function of sHSPs (Tsvetkova et al, 2002). HII phases are however key to chloroplast heat acclimation because when they emerge under stress, they recruit and activate the xanthophyll cycle enzyme, violaxanthin deepoxidase (VDE) (Dlouhý et al, 2020). VDE synthesizes zeaxanthin which quenches excess excitation energy and enhances membrane F I G U R E 3 Sensing and signalling of heat stress at the chloroplast.…”
Section: Adjustment Of Membrane Fluidity Through Changes In Membranementioning
Plants alter their morphology and cellular homeostasis to promote resilience under a variety of heat regimes. Molecular processes that underlie these responses have been intensively studied and found to encompass diverse mechanisms operating across a broad range of cellular components, timescales and temperatures. This review explores recent progress throughout this landscape with a particular focus on thermosensing in the model plant Arabidopsis. Direct temperature sensors include the photosensors phytochrome B and phototropin, the clock component ELF3 and an RNA switch. In addition, there are heat‐regulated processes mediated by ion channels, lipids and lipid‐modifying enzymes, taking place at the plasma membrane and the chloroplast. In some cases, the mechanism of temperature perception is well understood but in others, this remains an open question. Potential novel thermosensing mechanisms are based on lipid and liquid–liquid phase separation. Finally, future research directions of high temperature perception and signalling pathways are discussed.
“…According to this model, bilayer and non-bilayer phases co-exist as a dynamic equilibrium between the different lipid phases [ 71 , 72 , 73 , 74 ]. This is most clearly indicated by reversible co-solute-, temperature- and pH-dependent changes in the lipid-phase behavior of thylakoid membranes [ 73 , 75 ]. The shifts in equilibrium may represent states of various physiological activities in these light-energy converting membranes.…”
Section: Non-bilayer Structures and Possible Implications In Cardiovascular Diseasementioning
The present review is an attempt to conceptualize a contemporary understanding about the roles that cardiolipin, a mitochondrial specific conical phospholipid, and non-bilayer structures, predominantly found in the inner mitochondrial membrane (IMM), play in mitochondrial bioenergetics. This review outlines the link between changes in mitochondrial cardiolipin concentration and changes in mitochondrial bioenergetics, including changes in the IMM curvature and surface area, cristae density and architecture, efficiency of electron transport chain (ETC), interaction of ETC proteins, oligomerization of respiratory complexes, and mitochondrial ATP production. A relationship between cardiolipin decline in IMM and mitochondrial dysfunction leading to various diseases, including cardiovascular diseases, is thoroughly presented. Particular attention is paid to the targeting of cardiolipin by Szeto–Schiller tetrapeptides, which leads to rejuvenation of important mitochondrial activities in dysfunctional and aging mitochondria. The role of cardiolipin in triggering non-bilayer structures and the functional roles of non-bilayer structures in energy-converting membranes are reviewed. The latest studies on non-bilayer structures induced by cobra venom peptides are examined in model and mitochondrial membranes, including studies on how non-bilayer structures modulate mitochondrial activities. A mechanism by which non-bilayer compartments are formed in the apex of cristae and by which non-bilayer compartments facilitate ATP synthase dimerization and ATP production is also presented.
“…Fatty acids composition (with the proportion of saturated and unsaturated fatty acids) influences lipid composition (specific proportions) and organization in plant membranes. For example, the percentage content of lipids in the thylakoid membranes of green plants is as follows: MGDG~50%, DGDG~25-30%, SQDG~5-15%, PG~5-15% [70,71]. The most popular fatty acids in the skeleton of plant galactolipids are 18:3/16:3 as 34:6 MGDG, 18:3/18:3 as 36:6 MGDG, 18:3/16:0 as 34:3 DGDG, and 18:3/18:3 DGDG in the approximate proportion: 80%, 16%, 16%, 70%, respectively [72].…”
Section: Lipids Organization In Membranesmentioning
confidence: 99%
“…The studies concerning the location of the xanthophyll cycle in the transient membrane domain combined with LHCII, MGDG, VDE allowed to prove that MGDG have a crucial function in the stabilization of the structure of the LHCII protein in prevention its aggregation in PSII [71].…”
Section: Lipids In Xanthophyll Cyclementioning
confidence: 99%
“…The important functions of MGDG are to promote membrane stacking, stabilizing the inner membrane leaflet in grana disc [ 88 ] and conservation of photosynthetic energy [ 94 ]. Furthermore, the proportion of the thylakoid nonbilayer lipids are crucial, because the higher content of the MGDG is responsible for the membrane permeability and thermal stability of PSII [ 71 ]. …”
Section: Lipids Organization In Membranesmentioning
The paper focuses on the selected plant lipid issues. Classification, nomenclature, and abundance of fatty acids was discussed. Then, classification, composition, role, and organization of lipids were displayed. The involvement of lipids in xantophyll cycle and glycerolipids synthesis (as the most abundant of all lipid classes) were also discussed. Moreover, in order to better understand the biomembranes remodeling, the model (artificial) membranes, mimicking the naturally occurring membranes are employed and the survey on their composition and application in different kind of research was performed. High level of lipids remodeling in the plant membranes under different environmental conditions, e.g., nutrient deficiency, temperature stress, salinity or drought was proved. The key advantage of lipid research was the conclusion that lipids could serve as the markers of plant physiological condition and the detailed knowledge on lipids chemistry will allow to modify their composition for industrial needs.
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