ESCRT-III proteins are involved in many membrane remodeling processes including multivesicular body biogenesis as first discovered in yeast. In humans, ESCRT-III CHMP2 exists as two isoforms, CHMP2A ...and CHMP2B, but their physical characteristics have not been compared yet.
Here, we use a combination of techniques on biomimetic systems and purified proteins to study their affinity and effects on membranes. We establish that CHMP2B binding is enhanced in the presence of PI(4,5)P2 lipids. In contrast, CHMP2A does not display lipid specificity and requires CHMP3 for binding significantly to membranes. On the micrometer scale and at moderate bulk concentrations, CHMP2B forms a reticular structure on membranes whereas CHMP2A (+CHMP3) binds homogeneously. Thus, CHMP2A and CHMP2B unexpectedly induce different mechanical effects to membranes: CHMP2B strongly rigidifies them while CHMP2A (+CHMP3) has no significant effect.
We therefore conclude that CHMP2B and CHMP2A exhibit different mechanical properties and might thus contribute differently to the diverse ESCRT-III-catalyzed membrane remodeling processes.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Many cellular processes such as endosomal vesicle budding, virus budding, and cytokinesis require extensive membrane remodeling by the endosomal sorting complex required for transport III ...(ESCRT-III). ESCRT-III protein family members form spirals with variable diameters in vitro and in vivo inside tubular membrane structures, which need to be constricted to proceed to membrane fission. Here, we show, using high-speed atomic force microscopy and electron microscopy, that the AAA-type adenosine triphosphatase VPS4 constricts and cleaves ESCRT-III CHMP2A-CHMP3 helical filaments in vitro. Constriction starts asymmetrically and progressively decreases the diameter of CHMP2A-CHMP3 tubular structure, thereby coiling up the CHMP2A-CHMP3 filaments into dome-like end caps. Our results demonstrate that VPS4 actively constricts ESCRT-III filaments and cleaves them before their complete disassembly. We propose that the formation of ESCRT-III dome-like end caps by VPS4 within a membrane neck structure constricts the membrane to set the stage for membrane fission.
Nature Communications 8: Article number: 7093 (2015); Published: 12 May 2015; Updated: 29 September 2017 An error was inadvertently introduced into the fifth sentence of the Abstract in the original ...version of this Article. The sentence should have stated ‘Force spectra determined that the S4 transmembrane domain is mechanically coupled to S5 in the open state, but S3 in the closed state’ and not ‘Force spectra determined that the S4 transmembrane domain is mechanically coupled to S5 in the closed state, but S3 in the open state’.
Cyclic nucleotide-gated (CNG) channels mediate transduction in several sensory neurons. These channels use the free energy of CNs' binding to open the pore, a process referred to as gating. CNG ...channels belong to the superfamily of voltage-gated channels, where the motion of the α-helix S6 controls gating in most of its members. To date, only the open, cGMP-bound, structure of a CNG channel has been determined at atomic resolution, which is inadequate to determine the molecular events underlying gating. By using electrophysiology, site-directed mutagenesis, chemical modification, and Single Molecule Force Spectroscopy, we demonstrate that opening of CNGA1 channels is initiated by the formation of salt bridges between residues in the C-linker and S5 helix. These events trigger conformational changes of the α-helix S5, transmitted to the P-helix and leading to channel opening. Therefore, the superfamily of voltage-gated channels shares a similar molecular architecture but has evolved divergent gating mechanisms.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Arsenic endosmosis causes a severe threat to human health within the developing countries. This study assessed the levels of geogenic arsenic and other heavy metals affecting the release of As in the ...aquifers within the drinking water sources in Bhojpur district of Bihar, India. Eighteen water samples were collected in triplicates from hand-dug wells in six neighboring villages in proximity to the River Ganga namely Bakhorapur, Gaziapur, Parasrampur (or Kanhachhapara), Saraiya, Paiga and Gundiinin. The physicochemical parameters, ionic content and heavy metal analysis of the collected water samples indicated the region to be highly contaminated with arsenic, zinc, manganese and iron. The arsenic and iron concentration ranged between 24.3 and 168.07 μg/L and 0.17–1.16 mg/L respectively, indicating the excessive withdrawal of groundwater for domestic and irrigation purposes with a significant correlation between both the metals. Elevated concentration of zinc in the region attributed to the excessive application of chemical fertilizers and pesticides. Concentration of manganese was also in the higher range of 0.05–1.15 mg/L, primarily due to the urbanized industrial activities. Human health risk assessment within two population groups in the region indicated that the overall water quality is slightly contaminated but the risk associated with it is low. Water Quality Index ranged from 29 to 48, signifying the water quality to be poor. Residual sodium carbonate values indicated that few water sample sources are not suitable for irrigation purposes whereas, sodium adsorption ratio (SAR) values were within the acceptable limits to be used for irrigation.
•Detailed water quality parameters were analyzed statistically.•The range of arsenic content in the study area was 24 ppb–168.ppb.•Piper plot revealed the cationic and anionic dominance of Ca2+, Mg2+, Na+, K+ and HCO3−/CO32−.•WQI indicated requirement for improvement of the prevailing water quality.•SAR and RAC value revealed the usage of water for irrigation purposes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The present paper dealt with the annual dynamics of the absorption coefficient of chromophoric dissolved organic matter at 440nm {aCDOM(440)} during February 2015 to January 2016 in the continental ...shelf of northern Bay of Bengal (nBoB) for the first time. Sea surface salinity (SSS), chlorophyll-a (Chl-a), total suspended matter (TSM) were also analyzed. It was hypothesized that CDOM should exhibit significant spatial and temporal variability in this region. aCDOM(440) and spectral slope ranged between 0.1002m−1–0.6631m−1 and 0.0071nm−1–0.0229nm−1 respectively during the entire study period. Higher values of aCDOM(440) were observed in the near shore stations and gradually decreased towards the offshore. Significant seasonal variability of aCDOM(440) was observed between the monsoon and non-monsoon seasons (p<0.05). Thus the framed hypothesis was successfully accepted by means of the present study. The CDOM was mainly found to be of allochthonous character in this region. aCDOM(440) portrayed a significant negative linear relationship with SSS (R2=0.80; p<0.05) implying conservative mixing of marine and terrestrial end members. However, examining the spatial variability of the relationship, it was observed that this relationship was significant only in the nearshore stations. While examining the seasonal variability of this relationship, it was found to be most significant during the monsoon (R2=0.81; p<0.05). Thus it was inferred that whenever the SSS gradient was higher, the relationship between aCDOM(440) and SSS was found to be most significant.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Chemiresistive MOS-based acetone sensing device is a futuristic pathway for non-invasive diagnosis of diabetes. Although their potential deployment is restricted till now due to lack of selective, ...low temperature operated ppm-level sensors. In this work, we demonstrated synthesis of iron doped reduced graphene oxide (rGO) decorated WO3 nanocomposites in a facile, environment friendly wet chemical sol-gel process. The as-synthesized nanocomposites were comprehensively characterized by using different characterization techniques. A maximum ~78% sensing response was obtained for the optimized composition of ~10 wt% Fe doped 3 wt% rGO decorated WO3 based thin film (thickness ~700 nm) sensor towards ~10 ppm acetone gas. This sensing performance was observed at comparatively low working temperature of ~130 °C with fast response (~20 s) and recovery (~75 s) time. The efficacy of the fabricated sensors was established by their capabilities to sense a very low concentration of ~1 ppm acetone under similar working environment. Further illustration of versatility of the sensors revealed that, the sensors could be able to manifest a repeatable and reproducible sensing performance with prolong stability and superior selectivity for acetone over other interfering gases. The acetone sensing mechanism was illustrated with the help of electron depletion model and impedance spectroscopy study. Impedance spectroscopy quantifies different electrical properties and enlightens the smooth electronic transition mechanism between analyte and sensing material.
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•Novel Fe doped reduced graphene oxide (rGO) decorated WO3 nanocomposite was prepared using a facile sol-gel procedure.•Fabricated Taguchi type thin film sensor exhibited ~ 78 % sensing response towards ~10 ppm acetone at 130°C.•The sensor was also capable to detect very low concentration (~1 ppm) of acetone with fast response and recovery time.•The sensor revealed reproducible performance over time with minimum interference from other interfering gases.•Impedance spectroscopy was used to analyze the sensing mechanism with comprehensive illustration of electrical properties.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In the present work, reduced graphene oxide (rGO) decorated NiO-SnO2 nanocomposites were synthesized by using a facile sol-gel process and their structural (XRD, FTIR, Raman), morphological (BET, ...FESEM, TEM), and optical (UV-Vis, PL) characterizations were carried out. The as-synthesized NiO-SnO2 nanocomposite exhibited an enhancement of surface area after the incorporation of rGO and this substantial increment was expected to be beneficial for gas sensing at room temperature. Therefore, Taguchi-type sensors were fabricated and deployed for the detection of VOCs. The optimized sensor containing ∼ 3 wt% rGO in NiO-SnO2 nanocomposite demonstrated an excellent sensing response (Rg/Ra ∼ 7.8) towards ∼ 10 ppm acetone at room temperature (30 ± 5 °C) with response and recovery time of ∼ 10 s and ∼ 30 s respectively. It also exhibited good reproducibility and stability over ∼ 3 months. Additionally, this sensor selectively detected trace concentration (< 1 ppm) of acetone in exhaled human breath (ethanol present in a healthy person’s exhaled breath is insignificant), which is a non-invasive biomarker of diabetes. The sensing performance was analyzed from an electronic transportation point-of-view and consequent band structure modulation. The electrical property of the sensing material was illustrated using impedance spectroscopy to support the sensing mechanism.
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•rGO decorated NiO-SnO2 nanocomposites were prepared using sol-gel process.•Optimized Taguchi type sensor showed ∼ 7.8 response in ∼10 ppm acetone at ∼ 30 °C.•Sensor showed reproducible sensing performance and cross sensitivity was negligible.•Optimized sensor used to detect acetone (biomarker of diabetes) in exhaled breath.•The electrical properties of sensors were elucidated by impedance spectroscopy.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The vast usage of synthetic plastics has led to the global problem of plastic pollution which in turn has positively impacted the concerns regarding microplastic pollution. The major factor ...responsible for the increased level of pollution is the smaller size of microplastics which helps in its transportation across the globe. It has been found in most remote areas like glaciers and Antarctic regions where it is difficult for other contaminants to reach. This is ensured by the physicochemical cycle of plastic. They can either be produced for different applications or generated through the fragmentation of large plastic particles. Different studies have shown the accumulation of microplastics in different organisms, especially in aquatic animals leading to their entry into the food chain. The ultimate fate of the microplastics is accumulation inside the human body posing the risk of different health conditions like cancer, diabetes, and allergic reactions. The present review summarizes a detailed discussion on the current status of microplastic pollution, their effect on different organisms, and its impact on human health with a case study on the human health risk assessment for analyzing the global rate of microplastic ingestion.
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CEKLJ, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The determination at atomic resolution of the three-dimensional molecular structure of membrane proteins such as receptors and several ion channels has been a major breakthrough in structural ...biology. The molecular structure of several members of the superfamily of voltage-gated ionic channels such as K+ and Na+ is now available. However, despite several attempts, the molecular structure at atomic resolution of the full cyclic nucleotide-gated (CNG) ion channel, although a member of the same superfamily of voltage-gated ion channels, has not been obtained yet, neither by X-ray crystallography nor by electron cryomicroscopy (cryo-EM). It is possible that CNG channels have a high structural heterogeneity, making difficult crystallization and single-particle analysis. To address this issue, we have combined single-molecule force spectroscopy (SMFS) and electrophysiological experiments to characterize the structural heterogeneity of CNGA1 channels expressed in Xenopus laevis oocytes. The unfolding of the cytoplasmic domain had force peaks, occurring with a probability from 0.2 to 0.96. Force peaks during the unfolding of the transmembrane domain had a probability close to 1, but the distribution of the increase in contour length between two successive force peaks had multiple maxima differing by tens of nanometers. Concomitant electrophysiological experiments showed that the rundown in mutant channels S399C is highly variable and that the effect of thiol reagents when specific residues were mutated was consistent with a dynamic structural heterogeneity. These results show that CNGA1 channels have a wide spectrum of native conformations that are difficult to detect with X-ray crystallography and cryo-EM.
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IJS, KILJ, NUK, PNG, UL, UM, UPUK
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