The structure of the archaeal nuclease RecJ2 implicates its catalytic mechanism and inability to interact with GINS.

Bacterial RecJ exhibits 5'→3' exonuclease activity that is specific to ssDNA; however, archaeal RecJs show 5' or 3' exonuclease activity. The hyperthermophilic archaea Methanocaldococcus jannaschii encodes the 5'-exonuclease MjRecJ1 and the 3'-exonuclease MjRecJ2. In addition to nuclease activity, archaeal RecJ interacts with GINS, a structural subcomplex of the replicative DNA helicase complex. However, MjRecJ1 and MjRecJ2 do not interact with MjGINS. Here, we report the structural basis for the inability of the MjRecJ2 homologous dimer to interact with MjGINS and its efficient 3' hydrolysis polarity for short dinucleotides. Based on the crystal structure of MjRecJ2, we propose that the interaction surface of the MjRecJ2 dimer overlaps the potential interaction surface for MjGINS and blocks the formation of the MjRecJ2-GINS complex. Exposing the interaction surface of the MjRecJ2 dimer restores its interaction with MjGINS. The cocrystal structures of MjRecJ2 with substrate dideoxynucleotides or product dCMP/CMP show that MjRecJ2 has a short substrate binding patch, which is perpendicular to the longer patch of bacterial RecJ. Our results provide new insights into the function and diversification of archaeal RecJ/Cdc45 proteins.

Detectability of Single Spinless Stellar-Mass Black Holes through Gravitational Lensing of Gravitational Waves with Advanced LIGO.

We investigate the detectability of gravitational waves that have been lensed by a spinless stellar-mass black hole, with respect to the advanced LIGO. By solving the full relativistic linear wave equations in the spacetime of a Schwarzschild black hole, we find that the strong gravity can create unique signals in the lensed waveform, particularly during the merger and ring-down stages. The differences in terms of fitting factor between the lensed waveform and best-fitted unlensed general relativity template with spin precession and higher-order multipoles are greater than 5% for the lens black hole mass within 70M_{⊙}

Genetically predicted high sex hormone binding globulin was associated with decreased risk of polycystic ovary syndrome.

BACKGROUND: Previous observational studies have indicated an inverse correlation between circulating sex hormone binding globulin (SHBG) levels and the incidence of polycystic ovary syndrome (PCOS). Nevertheless, conventional observational studies may be susceptible to bias. Consequently, we conducted a two-sample Mendelian randomization (MR) investigation to delve deeper into the connection between SHBG levels and the risk of PCOS. METHODS: We employed single-nucleotide polymorphisms (SNPs) linked to serum SHBG levels as instrumental variables (IVs). Genetic associations with PCOS were derived from a meta-analysis of GWAS data. Our primary analytical approach relied on the inverse-variance weighted (IVW) method, complemented by alternative MR techniques, including simple-median, weighted-median, MR-Egger regression, and MR Pleiotropy RESidual Sum and Outlier (MR-PRESSO) testing. Additionally, sensitivity analyses were conducted to assess the robustness of the association. RESULTS: We utilized 289 SNPs associated with serum SHBG levels, achieving genome-wide significance, as instrumental variables (IVs). Our MR analyses revealed that genetically predicted elevated circulating SHBG concentrations were linked to a reduced risk of PCOS (odds ratio (OR) = 0.56, 95% confidence interval (CI): 0.39-0.78, P = 8.30 × 10-4) using the IVW method. MR-Egger regression did not detect any directional pleiotropic effects (P intercept = 0.626). Sensitivity analyses, employing alternative MR methods and IV sets, consistently reaffirmed our results, underscoring the robustness of our findings. CONCLUSIONS: Through a genetic epidemiological approach, we have substantiated prior observational literature, indicating a potential causal inverse relationship between serum SHBG concentrations and PCOS risk. Nevertheless, further research is needed to elucidate the underlying mechanism of SHBG in the development of PCOS.

Carotid blood flow changes following a simulated end-inspiratory occlusion maneuver measured by ultrasound can predict hypotension after the induction of general anesthesia: an observational study.

BACKGROUND: The primary purpose of this study was to investigate the predictive value of alterations in cervical artery hemodynamic parameters induced by a simulated end-inspiratory occlusion test (sEIOT) measured by ultrasound for predicting postinduction hypotension (PIH) during general anesthesia. METHODS: Patients undergoing gastrointestinal tumor resection under general anesthesia were selected for this study. Ultrasound has been utilized to assess hemodynamic parameters in carotid artery blood flow before induction, specifically focusing on variations in corrected flow time (ΔFTc) and peak blood flow velocity (ΔCDPV), both before and after sEIOT. Anesthesia was induced by midazolam, sufentanil, propofol, and rocuronium, and blood pressure (BP) and heart rate (HR) were recorded within the first 10 min following endotracheal intubation. PIH was defined as fall in systolic blood pressure (SBP) or mean arterial pressure (MAP) by > 30% of baseline or MAP to < 60 mm Hg. RESULTS: The area under the receiver operating characteristic curves (AUC) for carotid artery ΔFTc was 0.88 (95%CI, 0.81 to 0.96; P < 0.001), and the optimal cutoff value was -16.57%, with a sensitivity of 91.4% and specificity of 77.60%. The gray zone for carotid artery ΔFTc was -16.34% to -15.36% and included 14% of the patients. The AUC for ΔCDPV was 0.54, with an optimal cutoff value of -1.47%. The sensitivity and specificity were calculated as 55.20% and 57.10%, respectively. CONCLUSION: The corrected blood flow time changes in the carotid artery induced by sEIOT can predict hypotension following general anesthesia-induced hypotension, wherein ΔFTc less than 16.57% is the threshold. TRIAL REGISTRATION: Chinese Clinical Trial Registry ( www.chictr.org.cn ; 20/06/2023; ChiCTR2300072632).

Causal impact of DNA methylation on refracture in elderly individuals with osteoporosis - a prospective cohort study.

BACKGROUND: Osteoporotic vertebral compression fractures (OVCF) in the elderly increase refracture risk post-surgery, leading to higher mortality rates. Genome-wide association studies (GWAS) have identified susceptibility genes for osteoporosis, but the phenotypic variance explained by these genes has been limited, indicating the need to explore additional causal factors. Epigenetic modifications, such as DNA methylation, may influence osteoporosis and refracture risk. However, prospective cohorts for assessing epigenetic alterations in Chinese elderly patients are lacking. Here, we propose to conduct a prospective cohort study to investigate the causal network of DNA polymorphisms, DNA methylation, and environmental factors on the development of osteoporosis and the risk of refracture. METHODS: We will collect vertebral and peripheral blood from 500 elderly OVCF patients undergoing surgery, extract DNA, and generate whole genome genotype data and DNA methylation data. Observation indicators will be collected and combined with one-year follow-up data. A healthy control group will be selected from a natural population cohort. Epigenome-wide association studies (EWAS) of osteoporosis and bone mineral density will be conducted. Differential methylation analysis will compare candidate gene methylation patterns in patients with and without refracture. Multi-omics prediction models using genetic variants and DNA methylation sites will be built to predict OVCF risk. DISCUSSION: This study will be the first large-scale population-based study of osteoporosis and bone mineral density phenotypes based on genome-wide data, multi-time point methylation data, and phenotype data. By analyzing methylation changes related to osteoporosis and bone mineral density in OVCF patients, the study will explore the feasibility of DNA methylation in evaluating postoperative osteoporosis intervention effects. The findings may identify new molecular markers for effective anti-osteoporosis treatment and inform individualized prevention and treatment strategies. TRIAL REGISTRATION: chictr.org.cn ChiCTR2200065316, 02/11/2022.

Analysis of the association of sugammadex with the length of hospital stay in patients undergoing abdominal surgery: a retrospective study.

BACKGROUND: Sugammadex is a newer medication used for rapid and reliable reversal of neuromuscular blockade. This study evaluated whether sugammadex could reduce the length of postoperative hospital stay in patients undergoing abdominal surgery. METHODS: This single center retrospective cohort study included patients who underwent major abdominal surgery between January 2015 and October 2019. Patients were randomized according to reversal with sugammadex or spontaneous recovery. The primary outcome was length of postoperative hospital stay. The secondary outcomes were length of post-anesthetic care unit (PACU) stay, postoperative ambulation time, time-to-first-defecation, and incidence of pulmonary complications. After 1:1 propensity score matching, univariate and multiple linear regression analyses estimated the differences in outcomes. RESULTS: Of the 1614 patients, 517 received sugammadex and 645 spontaneously recovered. After adjusting for potential confounders, non-linear relationship was detected between administration of sugammadex and the length of postoperative hospital stay (ß = 0.29 95% confidence interval {CI}: [- 1.13, - 0.54], P = 0.4912). However, it was associated with shorter PACU stay (ß = - 20.30 95% CI: [- 24.48, - 17.11], P < 0.0001), shorter time to postoperative ambulation movement (ß = - 0.43 95% CI: [- 0.62, - 0.23], P < 0.0001), and reduced time-to-first-defecation (ß = - 2.25 95% CI: [- 0.45, - 0.05], P = 0.0129), when compared to the spontaneously recovered group. The incidence of pneumonia in the sugammadex group was significantly lower than that in the spontaneously recovered group (18.6% [44/237] vs. 39.2% [93/237] P < 0.05). CONCLUSIONS: Neuromuscular blockade reversal with sugammadex after abdominal surgery demonstrated an excellent recovery profile and was associated with decreased risk of pneumonia, although it did not affect the length of postoperative hospital stay.

Translesion synthesis of apurinic/apyrimidic site analogues by Y-family DNA polymerase Dbh from Sulfolobus acidocaldarius.

Apurinic/apyrimidic (AP) sites are severe DNA damages and strongly block DNA extension by major DNA polymerases. Y-family DNA polymerases possess a strong ability to bypass AP sites and continue the DNA synthesis reaction, which is called translesion synthesis (TLS) activity. To investigate the effect of the molecular structure of the AP site on the TLS efficiency of Dbh, a Y-family DNA polymerase from Sulfolobus acidocaldarius, a series of different AP site analogues (various spacers) are used to characterize the bypass efficiency. We find that not only the molecular structure and atomic composition but also the number and position of AP site analogues determine the TLS efficiency of Dbh. Increasing the spacer length decreases TLS activity. The TLS efficiency also decreases when more than one spacer exists on the DNA template. The position of the AP site analogues is also an important factor for TLS. When the spacer is opposite to the first incorporated dNTPs, the TLS efficiency is the lowest, suggesting that AP sites are largely harmful for the formation of hydrogen bonds. These results deepen our understanding of the TLS activity of Y-family DNA polymerases and provide a biochemical basis for elucidating the TLS mechanism in Sulfolobus acidocaldarius cells.

Dynamic Heterogeneous User Generated Contents-Driven Relation Assessment via Graph Representation Learning.

Cross-domain decision-making systems are suffering a huge challenge with the rapidly emerging uneven quality of user-generated data, which poses a heavy responsibility to online platforms. Current content analysis methods primarily concentrate on non-textual contents, such as images and videos themselves, while ignoring the interrelationship between each user post's contents. In this paper, we propose a novel framework named community-aware dynamic heterogeneous graph embedding (CDHNE) for relationship assessment, capable of mining heterogeneous information, latent community structure and dynamic characteristics from user-generated contents (UGC), which aims to solve complex non-euclidean structured problems. Specifically, we introduce the Markov-chain-based metapath to extract heterogeneous contents and semantics in UGC. A edge-centric attention mechanism is elaborated for localized feature aggregation. Thereafter, we obtain the node representations from micro perspective and apply it to the discovery of global structure by a clustering technique. In order to uncover the temporal evolutionary patterns, we devise an encoder-decoder structure, containing multiple recurrent memory units, which helps to capture the dynamics for relation assessment efficiently and effectively. Extensive experiments on four real-world datasets are conducted in this work, which demonstrate that CDHNE outperforms other baselines due to the comprehensive node representation, while also exhibiting the superiority of CDHNE in relation assessment. The proposed model is presented as a method of breaking down the barriers between traditional UGC analysis and their abstract network analysis.

Estimates of PM2.5 concentrations spatiotemporal evolution across China considering aerosol components in the context of the Reform and Opening-up.

With astonishing and rapid development in China since the Reform and Opening-up in 1978, serious air pollution has become a great challenge. A better understanding of the response of PM2.5 pollution to socioeconomic development after the Reform and Opening-up policy is benefit for pollution control. However, heterogeneous influences of biophysical and socioeconomic activities on PM2.5 pollution pose great challenges in statistical simulation of PM2.5. Few statistical model regards aerosol species as the explanatory variables for heterogeneous formation mechanism to retrieve PM2.5 concentration. In this research, monthly PM2.5 concentration in China during 1980-2020 was reconstructed by a novel statistical strategy considering aerosol components (AC-RF). Three cross-validation (CV) methods, sample-based CV, spatial-based CV and temporal-based CV results indicated satisfactory performance of AC-RF model with correlation coefficient (R) of 0.92, 0.90, 0.86, respectively. A three-stage concluded on PM2.5 concentration annual variation in China was drawn as followed: Before 2000, PM2.5 level in China represented smooth evolution and mainly influenced by natural events with polluted region locating in Xinjiang province, North China and Central China. Since 2000, PM2.5 concentration increased to high level in the context of rapid socioeconomic development. Severe air pollution covered Jing-Jin-Ji agglomeration, Central China and Sichuan Basin. During 2012-2020, PM2.5 declined and polluted region shrank, which was benefited by the strictest-ever air pollution control measures. Based on aerosol components analysis, sulfate aerosol exhibited the most significant increase trend in recent 40 years and black aerosol variation is the most closely related to PM2.5 pollution. In conclusion, unsustainable development is the culprit for air quality deterioration. Strict and continuous air pollution control strategies are effective for air quality improvement.

Pellets of phospholipids and d-glucose with improved intestinal absorption and oral bioavailability of salvianolic acid B.

Salvianolic acid B (SAB) is a widely used cardioprotective agent, while its clinical application was limited by poor intestinal absorption and low oral bioavailability. In this study, SAB phospholipid (SP) complex was first prepared to improve the lipophilicity of SAB and then combined with d-glucose to further enhance intestinal absorption. Compared with free SAB, SP or the mixture of SAB and d-glucose, combination of SP and d-glucose showed higher intestinal absorption evidenced by increased effective permeation coefficient (Peff) in the in situ single-pass intestinal perfusion (SPIP) assay. Subsequently, SP and d-glucose at mass ratio of 1:6, with the highest Peff of SAB, were chosen for the preparation of complexed pellets to improve oral absorption efficiency of SAB. As expected, the obtained pellets significantly enhanced oral bioavailability of SAB in the pharmacokinetic study characterized by increasing Cmax and AUC0-t of SAB by 14.88-fold and 5.02-fold than free SAB, respectively. In conclusion, combination of d-glucose in SP pellets can effectively improve the intestinal absorption and oral bioavailability of SAB.

Anti-NSCLC activity in vitro of Hsp90N inhibitor KW-2478 and complex crystal structure determination of Hsp90N-KW-2478.

KW-2478 is a promising anti-cancer lead compound targeting to the molecular chaperone heat shock protein 90 N (Hsp90N). Absence of complex crystal structure of Hsp90N-KW-2478, however, hampered further structure optimization of KW-2478 and understanding on the molecular interaction mechanism. Herein, a high-resolution complex crystal structure of Hsp90N-KW-2478 was determined by X-ray diffraction (XRD, resolution limit: 1.59 Å; PDB ID: 6LT8) and their molecular interaction was analyzed in detail, which suggested that KW-2478 perfectly bound in the N-terminal ATP-binding pocket of Hsp90 to disable its molecular chaperone function, therefore suppressed or killed cancer cells. The results from thermal shift assay (TSA, ΔTm, 18.82 ± 0.51 °C) and isothermal titration calorimetry (ITC, Kd, 7.30 ± 2.20 nM) suggested that there is an intense binding force and favorable thermodynamic changes during the process of KW-2478 binding with Hsp90N. Additionally, KW-2478 exhibited favorable anti-NSCLC activity in vitro, as it inhibited cell proliferation (IC50, 8.16 µM for A549; 14.29 µM for H1975) and migration, induced cell cycle arrest and promoted apoptosis. Thirty-six novel KW-2478 derivatives were designed, based on the complex crystal structure and molecular interaction analysis of Hsp90N-KW-2478 complex. Among them, twenty-two derivatives exhibited increased binding force with Hsp90N evaluated by molecular docking assay. The results would provide new guidance for anti-NSCLC new drug development based on the lead compound KW-2478.

Visualizing the nonlinear changes of a drug-proton antiporter from inward-open to occluded state.

Drug-proton antiporters (DHA) play an important role in multi-drug resistance, utilizing the proton-motive force to drive the expulsion of toxic molecules, including antibiotics and drugs. DHA transporters belong to the major facilitator superfamily (MFS), members of which deliver substrates by utilizing the alternating access model of transport. However, the transport process is still elusive. Here, we report the structures of SotB, a member of DHA1 family (TCDB: 2.A.1.2) from Escherichia coli. Four crystal structures of SotB were captured in different conformations, including substrate-bound occluded, inward-facing, and inward-open states. Comparisons between the four structures reveal nonlinear rigid-body movements of alternating access during the state transition from inward-open to occluded conformation. This work not only reveals the conformational dynamics of SotB but also deepens our understanding of the alternating access mechanism of MFS transporters.

Sirtuin 3 inhibits nuclear factor-κB signaling activated by a fatty acid challenge in bovine mammary epithelial cells.

Susceptibility to mastitis is highest during the peripartal (transition) period and is often concomitant with other comorbidities such as ketosis. Although infection with pathogenic microorganisms and immune-dysfunction around calving clearly play key roles in mastitis development, other metabolic factors also contribute. Sirtuin 3 (SIRT3), a mitochondrial deacetylase regulating energy and redox homeostasis, antagonizes the lipotoxic effects of nonesterified fatty acids (NEFA). Thus, we hypothesized that increases in circulating NEFA concentrations, as observed in the transition period, provokes inflammatory responses that can be reversed via activation of SIRT3. Here we aimed to study (1) proinflammatory NF-κB signaling and SIRT3 abundance in mammary tissue of ketotic cows and healthy controls, and (2) the effect of SIRT3 on NF-κB activation in bovine mammary epithelial cells (BMEC) treated with high levels of NEFA. The mammary gland biopsy samples were from a previous study, which included 15 healthy cows and 15 ketotic cows. Primary BMEC were isolated from 3 healthy Holstein cows with collagenase III digestion. Purified BMEC were incubated with or without SIRT3 overexpression adenovirus for 48 h, then treated with 0, 0.6, 1.2, or 2.4 mM NEFA for 24 h. Mammary tissue of ketotic cows was associated with lower protein abundance of SIRT3 along with greater NF-κB P65 phosphorylation levels (p-NF-κB P65), p-NF-κB P65:NF-κB P65 ratio, and mRNA abundance of IL1B and IL6. In BMEC, exogenous NEFA dose-dependently reduced protein abundance of SIRT3, but increased p-NF-κB P65, p-NF-κB P65:NF-κB P65 ratio, and mRNA abundance of IL1B and IL6. Compared with green fluorescent protein adenovirus vector + NEFA, overexpression of SIRT3 in NEFA-treated BMEC downregulated p-NF-κB P65 and mRNA abundance of IL1B and IL6. Immunofluorescence indicated that overexpression of SIRT3 inhibited nuclear translocation of NF-κB P65. Overall, our data demonstrated that ketosis is associated with a reduction in SIRT3 abundance and activation of NF-κB signaling in the mammary gland. In vitro data provided evidence that high NEFA concentrations inhibit SIRT3, which contributes to enhanced NF-κB signaling including nuclear translocation and a pro-inflammatory response. The data suggest a promising role of SIRT3 as a target for helping alleviate localized inflammation of the mammary gland resulting from exposure to high concentrations of NEFA.

Identification of Pyruvate Dehydrogenase E1 as a Potential Target against Magnaporthe oryzae through Experimental and Theoretical Investigation.

Magnaporthe oryzae (M. oryzae) is a typical cause of rice blast in agricultural production. Isobavachalcone (IBC), an active ingredient of Psoralea corylifolia L. extract, is an effective fungicide against rice blast. To determine the mechanism of IBC against M. oryzae, the effect of IBC on the metabolic pathway of M. oryzae was explored by transcriptome profiling. In M. oryzae, the expression of pyruvate dehydrogenase E1 (PDHE1), part of the tricarboxylic acid (TCA cycle), was significantly decreased in response to treatment with IBC, which was verified by qPCR and testing of enzyme activity. To further elucidate the interactions between IBC and PDHE1, the 3D structure model of the PDHE1 from M. oryzae was established based on homology modeling. The model was utilized to analyze the molecular interactions through molecular docking and molecular dynamics simulation, revealing that IBC has π-π stacking interactions with residue TYR139 and undergoes hydrogen bonding with residue ASP217 of PDHE1. Additionally, the nonpolar residues PHE111, MET174, ILE 187, VAL188, and MET250 form strong hydrophobic interactions with IBC. The above results reveal that PDHE1 is a potential target for antifungal agents, which will be of great significance for guiding the design of new fungicides. This research clarified the mechanism of IBC against M. oryzae at the molecular level, which will underpin further studies of the inhibitory mechanism of flavonoids and the discovery of new targets. It also provides theoretical guidance for the field application of IBC.

Anti-Inflammatory Action and Mechanisms of Resveratrol.

Resveratrol (3,4',5-trihy- droxystilbene), a natural phytoalexin polyphenol, exhibits anti-oxidant, anti-inflammatory, and anti-carcinogenic properties. This phytoalexin is well-absorbed and rapidly and extensively metabolized in the body. Inflammation is an adaptive response, which could be triggered by various danger signals, such as invasion by microorganisms or tissue injury. In this review, the anti-inflammatory activity and the mechanism of resveratrol modulates the inflammatory response are examined. Multiple experimental studies that illustrate regulatory mechanisms and the immunomodulatory function of resveratrol both in vivo and in vitro. The data acquired from those studies are discussed.

Investigating the biophysical and socioeconomic determinants of China tropospheric O3 pollution based on a multilevel analysis approach.

Severe tropospheric O3 pollution has swept across China in recent years. Consequently, investigation of tropospheric O3 concentration influencing mechanism is of significance for O3 pollution control in China. Previous studies have rarely detected combined impacts of natural factors and anthropogenic activities behind tropospheric O3 concentration in China at a national scale. Moreover, there is significant spatiotemporal heterogeneity of O3 pollution distribution in China due to the temporal and regional differences of socioeconomic and natural environmental condition in the vast territory. The targeted O3 control recommendations for different regions and seasons should be put forward in terms of the spatiotemporal heterogeneity of O3 concentration determinants. In this context, a three-level regression model integrating multi-scale biophysical and socioeconomic variables was proposed to explore the determinants of O3 pollution in China. The results showed that the tropospheric O3 concentration in the eastern and southeastern regions of China was strongly affected by meteorological conditions. In contrast, tropospheric O3 pollution concentrated in inland areas mainly depended on the emission intensity from anthropogenic sources.

Crystal structure of the Vibrio cholerae VqmA-ligand-DNA complex provides insight into ligand-binding mechanisms relevant for drug design.

VqmA is a highly conserved transcriptional regulator of the quorum-sensing system of Vibrio cholerae, a major human pathogen that continues to imperil human health. VqmA represses biofilm formation and plays an important role in V. cholerae pathogenicity in the human host. Although VqmA's biological function is well understood, the molecular mechanisms by which its specific ligand (and effector), 3,5-dimethylpyrazine-2-ol (DPO), controls transcription of the target gene, vqmR, remain obscure. To elucidate the molecular mechanism of DPO binding, we used structural analyses and biochemical assays to study the V. cholerae VqmA-DPO-DNA complex. These analyses revealed that VqmA contains an N-terminal homodimer domain (PAS) and a C-terminal DNA-binding domain (DBD). We observed that VqmA directly binds to a DPO molecule via a compact hydrophobic pocket, consisting of a six-stranded antiparallel ß-sheet and several α-helices. We also found that the VqmA dimer interacts with the quasi-palindromic sequence of the vqmR promoter through its DBD. The results of the biochemical studies indicated that a water atom and VqmA residues Phe-67 and Lys-101 play a key role in effector recognition, which is also assisted by Tyr-36 and Phe-99. This is the first molecular level view of the VqmA dimer bound to DPO and DNA. The structure-function analyses presented here improve our understanding of the complex mechanisms in the transcriptional regulation of VqmA in Vibrio spp. and may inform the design of drugs to manage V. cholerae infections.

Pyrethroid Carboxylesterase PytH from Sphingobium faniae JZ-2: Structure and Catalytic Mechanism.

Carboxylesterase PytH, isolated from the pyrethroid-degrading bacterium Sphingobium faniae JZ-2, could rapidly hydrolyze the ester bond of a wide range of pyrethroid pesticides, including permethrin, fenpropathrin, cypermethrin, fenvalerate, deltamethrin, cyhalothrin, and bifenthrin. To elucidate the catalytic mechanism of PytH, we report here the crystal structures of PytH with bifenthrin (BIF) and phenylmethylsulfonyl fluoride (PMSF) and two PytH mutants. Though PytH shares low sequence identity with reported α/ß-hydrolase fold proteins, the typical triad catalytic center with Ser-His-Asp triad (Ser78, His230, and Asp202) is present and vital for the hydrolase activity. However, no contact was found between Ser78 and His230 in the structures we solved, which may be due to the fact that the PytH structures we determined are in their inactive or low-activity forms. The structure of PytH is composed of a core domain and a lid domain; some hydrophobic amino acid residues surrounding the substrate from both domains form a deeper and wider hydrophobic pocket than its homologous structures. This indicates that the larger hydrophobic pocket makes PytH fit for its larger substrate binding; both lid and core domains are involved in substrate binding, and the lid domain-induced core domain movement may make the active center correctly positioned with substrates.IMPORTANCE Pyrethroid pesticides are widely applied in agriculture and household; however, extensive use of these pesticides also causes serious environmental and health problems. The hydrolysis of pyrethroids by carboxylesterases is the major pathway of microbial degradation of pyrethroids, but the structure of carboxylesterases and its catalytic mechanism are still unknown. Carboxylesterase PytH from Sphingobium faniae JZ-2 could effectively hydrolyze a wide range of pyrethroid pesticides. The crystal structures of PytH are solved in this study. This showed that PytH belongs to the α/ß-hydrolase fold proteins with typical catalytic Ser-His-Asp triad, though PytH has a low sequence identity (about 20%) with them. The special large hydrophobic binding pocket enabled PytH to bind bigger pyrethroid family substrates. Our structures shed light on the substrate selectivity and the future application of PytH and deepen our understanding of α/ß-hydrolase members.

Bcl-XL: A multifunctional anti-apoptotic protein.

B-cell lymphoma-extra large (Bcl-XL) is one of the anti-apoptotic proteins of the Bcl-2 family that is localized in the mitochondria. Bcl-XL is one of the key regulators of apoptosis that can also regulate other important cellular functions. Bcl-XL is overexpressed in many cancers, and its inhibitors have shown good therapeutic effects. Bcl-XL interacts with Beclin 1, a key factor regulating autophagy. Bcl-XL is essential for the survival of neurons and plays protective roles in neuronal injuries. It can promote the growth of neurons and the correct formation of neural networks, enhance synaptic plasticity, and control neurotoxicity. Bcl-XL can also promote the transport of Ca2+ to mitochondria, increase the production of ATP, and improve metabolic efficiency. In addition, targeting Bcl-XL has shown potential value in autoimmune diseases and aging. In this review, we summarize the functions of Bcl-XL in cancer, autophagy, Ca2+ signaling, neuroprotection, neuronal growth and synaptic plasticity, energy metabolism, immunity, and senescence as revealed by investigations conducted in the past 10 years. Moreover, we list some inhibitors that have been developed based on the functions of Bcl-XL.

Sirtuin 3 improves fatty acid metabolism in response to high nonesterified fatty acids in calf hepatocytes by modulating gene expression.

Sirtuin 3 (SIRT3), a mitochondrial deacetylase, is a key regulator of energy metabolism in the liver. In nonruminants, the hepatic abundance of SIRT3 is decreased in individuals with nonalcoholic fatty liver diseases, and recovery of SIRT3 alleviates hepatic triacylglycerol (TG) deposition. However, the level of SIRT3 expression and its effects on lipid metabolism in dairy cows have not been characterized. Here we studied the hepatic expression of SIRT3 in cows with fatty liver and the role of SIRT3 in fatty acid metabolism in bovine hepatocytes. This in vivo study involved 10 healthy cows and 10 cows with fatty liver, from which we collected samples of liver tissue and blood. Primary hepatocytes were isolated from Holstein calves and treated with 0, 0.5, or 1.0 mM nonesterified fatty acids (NEFA) for 24 h or transinfected with SIRT3 overexpression adenovirus (Ad-SIRT3)/SIRT3-short interfering (si)RNA for 48 h. Cows with fatty liver displayed lower serum glucose concentrations but higher serum NEFA and ß-hydroxybutyrate concentrations relative to healthy cows. Cows with fatty liver also had significant lower mRNA and protein abundance of hepatic SIRT3. Incubation of primary hepatocytes with NEFA reduced SIRT3 abundance in primary hepatocytes in a dose-dependent manner. Fatty acid (1 mM) treatment also markedly increased the abundance of acetyl-CoA carboxylase 1 (ACC1) and fatty acid synthase (FAS) but significantly decreased the abundance of carnitine palmitoyltransferase I (CPT1A), carnitine palmitoyltransferase II (CPT2), and acyl-CoA oxidase (ACO). Knockdown of SIRT3 by SIRT3-siRNA downregulated the mRNA abundance of CPT1A, CPT2, and ACO. In contrast, overexpression of SIRT3 by Ad-SIRT3 upregulated the mRNA abundance of CPT1A, CPT2, and ACO; downregulated the mRNA abundance of ACC1 and FAS; and consequently, decreased intracellular TG concentrations. Overexpression of SIRT3 ameliorated exogenous NEFA-induced TG accumulation by downregulating the abundance of ACC1 and FAS and upregulating the abundance of CPT1A, CPT2, and ACO in calf hepatocytes. Our data demonstrated that cows with fatty liver had lower hepatic SIRT3 contents, and an increase in SIRT3 abundance by overexpression mitigated TG deposition by modulating the expression of lipid metabolism genes in bovine hepatocytes. These data suggest a possible role of SIRT3 as a therapeutic target for fatty liver disease prevention in periparturient dairy cattle.