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关键词： CGH-1   CAR-1   NMR   ATPase   Structure   C   elegans  

摘要： A protein-RNA complex containing the RNA helicase CGH-1 and a germline specific RNA-binding protein CAR-1 is involved in various aspects of function in C. elegans. However, the structural basis for the assembly of this protein complex remains unclear. Here, we elucidate the molecular basis of the recognition of CGH-1 by CAR-1. Additionally, we found that the ATPase activity of CGH-1 is stimulated by NTL1a MIF4G domain in vitro. Furthermore, we determined the structures of the two RecA-like domains of CGH-1 by X-ray crystallography at resolutions of 1.85 and 2.40 ?, respectively. Structural and biochemical approaches revealed a bipartite interface between CGH-1 RecA2 and the FDF-TFG motif of CAR-1. NMR and structure-based mutations in CGH-1 RecA2 or CAR-1 attenuated or disrupted CGH-1 binding to CAR 1, assessed by ITC and GST-pulldown in vitro. These findings provide insights into a conserved mechanism in the recognition of CGH-1 by CAR-1. Together, our data provide the missing physical links in understanding the assembly and function of CGH-1 and CAR-1 in C. elegans. ? 2021 Elsevier Inc. All rights reserved.

关键词： Davidsonia pruriens   Davidsonia jerseyana   Phenolics   Minerals   Antioxidant activities   Sensory attributes  

摘要： Davidsonia pruriens (DP) and Davidsonia jerseyana (DJ) are a gourmet bushfood with a sweet and sour taste. This study investigated the biochemical content, antioxidant activities, and sensory attributes of DP and DJ fruit infusions in comparison with commercial forest fruits (FF) infusion. Total phenolic and anthocyanin content was higher in FF infusion compared to DP or DJ fruit infusions (P < 0.05). An abundant amount of gallic acid was found in DP and DJ fruit infusions (P < 0.05). Quercetin, kaempferol-3-O-rutinoside, and peonidin-3-sambu-bioside was detected only in DP and DJ fruit infusions (P < 0.05). However, a high level of oxalic acid, minerals and soluble sugars were observed in FF infusions (P < 0.05). The antioxidant capacities and overall likeness score of DP or DJ infusion were comparable with the commercial FF infusion. Therefore, bioactive compounds, antioxidant activities and sensory properties suggested that DP and DJ fruit infusion have the potential to become a commercial health promoting drink.

关键词： Modification   Peptides and proteins   Monomers   Molecular structure   Nicotinamide  

摘要： All life forms require nicotinamide adenine dinucleotide, NAD(+), and its reduced form NADH. They are redox partners in hundreds of cellular enzymatic reactions. Changes in the intracellular levels of total NAD (NAD(+) + NADH) and the (NAD(+)/NADH) ratio can cause cellular dysfunction. When not present in protein complexes, NADH and its phosphorylated form NADPH degrade through intricate mechanisms. Replenishment of a declining total NAD pool can be achieved with biosynthetic precursors that include one of the reduced forms of nicotinamide riboside (NR+), NRH. NRH, like NADH and NADPH, is prone to degradation via oxidation, hydration, and isomerization and, as such, is an excellent model compound to rationalize the nonenzymatic metabolism of NAD(P)H in a biological context. Here, we report on the stability of NRH and its propensity to isomerize and irreversibly degrade. We also report the preparation of two of its naturally occurring isomers, their chemical stability, their reactivity toward NRH-processing enzymes, and their cell-specific cytotoxicity. Furthermore, we identify a mechanism by which NRH degradation causes covalent peptide modifications, a process that could expose a novel type of NADH-protein modifications and correlate NADH accumulation with "protein aging." This work highlights the current limitations in detecting NADH's endogenous catabolites and in establishing the capacity for inducing cellular dysfunction.

关键词： Extracellular protease   Halophilic archaea   Enzyme properties  

摘要： Extracellular proteases from haloarchaea can expand the application fields of proteases. Exploring novel robust proteases is of great importance. An extracellular protease HlyA from Halococcus salifodinae was obtained by heterologous expression, affinity chromatography, in vitro refolding and gel filtration chromatography. Its activity was optimal at 45 degrees C, pH 9.0 and 1.5-2 M NaCl. Interestingly, although HlyA was from an extremely halophilic archaeon, it retained >75% of maximal activity in a broad NaCl concentration of 0.5-4 M. It displayed relatively stable activities over a wide range of temperature, pH and salinity. Thus, HlyA exhibited good temperature, pH and especially, salinity tolerance. Ca2+, Mg2+ and Sr2+ significantly enhanced the protease activity. HlyA activity was completely inhibited by phenylmethanesulfonyl fluoride (PMSF), suggesting it is a serine protease. HlyA showed good tolerance to some surfactants and organic solvents. The K-m and V-max values of HlyA for azocasein were calculated to be 0.72 mM and 21.98 U/mu g, respectively. HlyA was able to effectively degrade several protein substrates, including bovine hemoglobin, casein and azocasein. Generally, HlyA from the extremely halophilic archaeon Hcc. salifodinae is an alkaliphilic and low salt-adapted halolysin with high activity, thus representing an attractive candidate for various industrial uses. (c) 2021 Elsevier B.V. All rights reserved.

关键词： BDE-28   Brassica alboglabra   Cd   KAR1   Stress  

摘要： In this study, we have evaluated the role of karrikin (KAR¹) against the absorption and translocation of a persistent organic pollutant (POP), 2,4,4’-Tribromodiphenyl ether (BDE-28) in plants, in the presence of two other stressors, cadmium (Cd) and high temperature. Furthermore, it correlates the physiological damages of Brassica alboglabra with the three stresssors separately. The results revealed that the post-germination application of KAR¹ successfully augmented the growth (200%) and pertinent physiochemical parameters of B. alboglabra. KAR¹ hindered air absorption of BDE-28 in plant tissues, and reduced its translocation coefficient (TF). Moreover, BDE-28 was the most negatively correlated (−0.9) stressor with chlorophyll contents, while the maximum mitigation by KAR¹ was also achieved agaist BDE-28. The effect of temperature was more severe on soluble sugars (0.51), antioxidative machinery (−0.43), and osmoregulators (0.24). Cd exhibited a stronger inverse interrelation with the enzymatic antioxidant cascade. Application of KAR¹ mitigated the deleterious effects of Cd and temperature stress on plant physiological parameters along with reduced aero-concentration factor, TF, and metal tolerance index. The phytohormone reduced lipid peroxidation by decreasing synthesis of ROS and persuading its breakdown. The stability of cellular membranes was perhaps due to the commotion of KAR¹ as a growth-promoting phytohormone. In the same way, KAR¹ supplementation augmented the membrane stability index, antioxidant defense factors, and removal efficiency of the pollutants. Consequently, the exogenously applied KAR¹ can efficiently alleviate Cd stress, heat stress, and POP toxicity. © 2021