PIEZO channels respond to piconewton-scale forces to mediate critical physiological and pathophysiological processes
. Detergent-solubilized PIEZO channels form bowl-shaped trimers comprising a ...central ion-conducting pore with an extracellular cap and three curved and non-planar blades with intracellular beams
, which may undergo force-induced deformation within lipid membranes
. However, the structures and mechanisms underlying the gating dynamics of PIEZO channels in lipid membranes remain unresolved. Here we determine the curved and flattened structures of PIEZO1 reconstituted in liposome vesicles, directly visualizing the substantial deformability of the PIEZO1-lipid bilayer system and an in-plane areal expansion of approximately 300 nm
in the flattened structure. The curved structure of PIEZO1 resembles the structure determined from detergent micelles, but has numerous bound phospholipids. By contrast, the flattened structure exhibits membrane tension-induced flattening of the blade, bending of the beam and detaching and rotating of the cap, which could collectively lead to gating of the ion-conducting pathway. On the basis of the measured in-plane membrane area expansion and stiffness constant of PIEZO1 (ref.
), we calculate a half maximal activation tension of about 1.9 pN nm
, matching experimentally measured values. Thus, our studies provide a fundamental understanding of how the notable deformability and structural rearrangement of PIEZO1 achieve exquisite mechanosensitivity and unique curvature-based gating in lipid membranes.
PIEZO2 is a mechanosensitive cation channel that has a key role in sensing touch, tactile pain, breathing and blood pressure. Here we describe the cryo-electron microscopy structure of mouse PIEZO2, ...which is a three-bladed, propeller-like trimer that comprises 114 transmembrane helices (38 per protomer). Transmembrane helices 1-36 (TM1-36) are folded into nine tandem units of four transmembrane helices each to form the unusual non-planar blades. The three blades are collectively curved into a nano-dome of 28-nm diameter and 10-nm depth, with an extracellular cap-like structure embedded in the centre and a 9-nm-long intracellular beam connecting to the central pore. TM38 and the C-terminal domain are surrounded by the anchor domain and TM37, and enclose the central pore with both transmembrane and cytoplasmic constriction sites. Structural comparison between PIEZO2 and its homologue PIEZO1 reveals that the transmembrane constriction site might act as a transmembrane gate that is controlled by the cap domain. Together, our studies provide insights into the structure and mechanogating mechanism of Piezo channels.
The ryanodine receptors (RyRs) are high-conductance intracellular Ca(2+) channels that play a pivotal role in the excitation-contraction coupling of skeletal and cardiac muscles. RyRs are the largest ...known ion channels, with a homotetrameric organization and approximately 5,000 residues in each protomer. Here we report the structure of the rabbit RyR1 in complex with its modulator FKBP12 at an overall resolution of 3.8 Å, determined by single-particle electron cryomicroscopy. Three previously uncharacterized domains, named central, handle and helical domains, display the armadillo repeat fold. These domains, together with the amino-terminal domain, constitute a network of superhelical scaffold for binding and propagation of conformational changes. The channel domain exhibits the voltage-gated ion channel superfamily fold with distinct features. A negative-charge-enriched hairpin loop connecting S5 and the pore helix is positioned above the entrance to the selectivity-filter vestibule. The four elongated S6 segments form a right-handed helical bundle that closes the pore at the cytoplasmic border of the membrane. Allosteric regulation of the pore by the cytoplasmic domains is mediated through extensive interactions between the central domains and the channel domain. These structural features explain high ion conductance by RyRs and the long-range allosteric regulation of channel activities.
The evolutionarily conserved Piezo proteins, including Piezo1 and Piezo2, constitute a bona fide class of mechanosensitive (MS) cation channels, which play critical roles in various mammalian ...physiologies, including sensation of touch, proprioception and regulation of vascular development, and blood pressure. Furthermore, mutations in Piezos have been linked to various human genetic diseases, validating their potential as therapeutic targets. Thus, it is pivotal to understand how Piezo channels effectively convert mechanical force into selective cation permeation, and therefore precisely control the various mechanotransduction processes. On the basis of our recently determined cryoelectron microscopy structures of the full‐length 2547‐residue mouse Piezo1, structure‐guided mutagenesis, and electrophysiological and pharmacological characterizations, here we focus on reviewing the key structural features and functional components that enable Piezo1 to employ a lever‐like mechanogating mechanism to function as a sophisticated mechanotransduction channel.
The mechanosensitive Piezo1 channel possesses a 38‐TM topology model and forms a unique three‐bladed, propeller‐like structure comprising three structural and functional modules: the TM‐blade‐constituted mechanosensing module that consists of nine repetitive transmembrane helical units (THUs), the C‐terminal ion‐conducting pore module, and the transduction module including the beam, anchor, and CTD. The THU‐beam‐structure constitutes a lever‐like transduction pathway for long‐distance chemical‐ and mechanical gating of Piezo1.
•Urban green space decreased remarkably, land surface temperature increased and thermal environment deteriorated during rapid urbanization.•The main reason of LST increased is urban green space was ...converted to other land use types, especially is neighborhood green space reduction.•The role of urbanization in the increase and aggregation of high-temperature areas, as evidenced in the city center, as well as in the reduction and fragmentation of low-temperature areas, as shown in the urban fringe areas.
Taking Dalian City as the study area, the spatial distribution of urban green space and land surface temperature (LST), as well as their evolution in 1999, 2007 and 2013, were obtained through remote sensing (RS) interpretation and inversion. Landsat ETM and SPOT data were used for this purpose. By combining the temperature and vegetation index models (TVX), the effects of urban green space reduction on the thermal environment during city development were evaluated. The results show the following. (1) During 1999–2013, 88.1km2 of urban green space was converted to other land uses, accounting for a 29.4% reduction in urban green space in the study area. (2) During the study period, the LST in this area increased by +8.455K. The evolution of the regional thermal landscape can be characterized by increases in the LST, greater complexity of the thermal landscape structure, increase and aggregation of high-temperature areas, and reduction and fragmentation of low-temperature areas. (3) During the process of urbanization, urban green space with low land-surface temperature was converted to other land use types with high land-surface temperature. When development occurred at the price of urban green space, negative effects on the regional thermal environment were observed.
Thermostable cross-β structures are characteristic of pathological amyloid fibrils, but these structures cannot explain the reversible nature of fibrils formed by RNA-binding proteins such as fused ...in sarcoma (FUS), involved in RNA granule assembly. Here, we find that two tandem (S/G)Y(S/G) motifs of the human FUS low-complexity domain (FUS LC) form reversible fibrils in a temperature- and phosphorylation-dependent manner. We named these motifs reversible amyloid cores, or RAC1 and RAC2, and determined their atomic structures in fibrillar forms, using microelectron and X-ray diffraction techniques. The RAC1 structure features an ordered-coil fibril spine rather than the extended β-strand typical of amyloids. Ser42, a phosphorylation site of FUS, is critical in the maintenance of the ordered-coil structure, which explains how phosphorylation controls fibril formation. The RAC2 structure shows a labile fibril spine with a wet interface. These structures illuminate the mechanism of reversible fibril formation and dynamic assembly of RNA granules.
•Surface temperature characteristics are affected by many factors, such as building form and land use.•The spatial regression model can effectively explain the relationship between LST and each ...impact factor.•Rational planning of community land resources and landscape features can effectively mitigate urban heat islands.
Owing to increasing population densities and impervious surface areas, heat island effects increasingly dominate urban environments and hinder sustainable development. The urban spatial form plays an important role in mitigating urban heat islands. Taking Ganjingzi District, Dalian, as an example, this study considered urban spatial form at the community scale using spatial autocorrelation and spatial regression methods to explore 2003–2018 spatial and temporal differentiation characteristics and driving factors of Land Surface Temperature (LST). The LST of each community showed a gradually increasing trend; high values (>30°C) were concentrated in central and eastern areas; low values were (<25°C) was concentrated in the south and west. LSTs were influenced by spatial variables (e.g., land use); however, building form was only weakly related to LST. The global autocorrelation Moran’s I value for LST exceeded 0.7, indicating strong positive correlation in terms of spatial distribution. H-H and L-L LISA values were distributed in central and southern areas, respectively. The spatial error model (SEM) was a better fit than the spatial lag (SLM) or ordinary least squares models (OLS) and was used to explore these relationships. This study focuses on community surface temperature and hopes to provide a valuable reference for community planning, resource allocation and sustainable development.
The mechanosensitive Piezo channels function as key eukaryotic mechanotransducers. However, their structures and mechanogating mechanisms remain unknown. Here we determine the three-bladed, ...propeller-like electron cryo-microscopy structure of mouse Piezo1 and functionally reveal its mechanotransduction components. Despite the lack of sequence repetition, we identify nine repetitive units consisting of four transmembrane helices each-which we term transmembrane helical units (THUs)-which assemble into a highly curved blade-like structure. The last transmembrane helix encloses a hydrophobic pore, followed by three intracellular fenestration sites and side portals that contain pore-property-determining residues. The central region forms a 90 Å-long intracellular beam-like structure, which undergoes a lever-like motion to connect THUs to the pore via the interfaces of the C-terminal domain, the anchor-resembling domain and the outer helix. Deleting extracellular loops in the distal THUs or mutating single residues in the beam impairs the mechanical activation of Piezo1. Overall, Piezo1 possesses a unique 38-transmembrane-helix topology and designated mechanotransduction components, which enable a lever-like mechanogating mechanism.
A major component of bacterial biofilms is curli amyloid fibrils secreted by the curli biogenesis system. Understanding the curli biogenesis mechanism is critical for developing therapeutic agents ...for biofilm-related infections. Here we report a systematic study of the curli biogenesis system, highlighted by structural, biochemical and functional analysis of the secretion channel complexes (CsgF-CsgG) with and without the curli substrate. The dual-pore architecture of the CsgF-CsgG complex was observed and used to develop an approach to inhibit the curli secretion by physically reducing the size of the CsgF pore. We further elucidated the assembly of the CsgFG complex with curli components (CsgA and CsgB) and curli-cell association through CsgF. Importantly, the recognition of the CsgA substrate by CsgG was uncovered. Nine crevices outside of the CsgG channel provide specific and highly-conserved recognition sites for CsgA N-terminus. Together with analysis of CsgE, our study provides comprehensive insights into curli biogenesis.
A new strategy has been developed using peptides with amino and carboxylic functional groups as passivating ligands to produce methyl ammonium lead bromide (CH3NH3PbBr3) perovskite nanocrystals ...(PNCs) with excellent optical properties. The well‐passivated PNCs can only be obtained when both amino and carboxylic groups are involved, and this is attributed to the protonation reaction between NH2 and COOH that is essential for successful passivation of the PNCs. To better understand this synergistic effect, peptides with different lengths have been studied and compared. Due to the polar nature of peptides, peptide‐passivated PNCs (denoted as PNCspeptide) aggregate and precipitate from nonpolar toluene solvent, resulting in a high product yield (≈44%). Furthermore, the size of PNCspeptide can be varied from ≈3.9 to 8.6 nm by adjusting the concentration of the peptide, resulting in tunable optical properties due to the quantum confinement effect. In addition, CsPbBr3 PNCs are also synthesized with peptides as capping ligands, further demonstrating the generality and versatility of this strategy, which is important for generating high quality PNCs for photonics applications including light‐emitting diodes, optical sensing, and imaging.
Peptides with different lengths are used in the synthesis of perovskite nanocrystals (PNCs) as capping ligands. PNCspeptide with tunable size (≈3.9 to 8.6 nm), prepared by adjusting the concentration of the peptides, exhibit size‐dependent optical properties due to quantum confinement effect. Such PNCs with peptides conjugated on their surface have potential applications in biomedicine, including optical sensing and imaging.
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