Dynamic assembly and subcellular localization of class I lanthipeptide biosynthesis complexes

Lanthipeptides belong to a family of ribosomally synthesized and posttranslationally modified peptides (RiPPs) containing (methyl)lanthionine residues. Commonly, class I lanthipeptides are synthesized by a putative membrane-associated lanthionine synthetase complex, which consists of the dehydratase LanB, the cyclase LanC, and the ABC transporter LanT. Despite intensive mechanistic studies on the individual proteins, the details on how these proteins interact are still not elucidated. In this thesis, we described the subcellular localization and assembly process of the nisin biosynthetic machinery NisBTC in the coccoid bacterium Lactococcus lactis by mutational analyses and fluorescence microscopy. Notably, the dynamic recruitment of NisT by NisBC from the cell membrane to the old cell pole was observed. Employing a platform we developed for nisin production in the rod-shaped bacterium Bacillus subtilis, the formation dynamics of the NisBTC complex were further investigated, which are likely associated with proteins residing in lipid rafts. From the above systems, the intact NisBTC complex was successfully isolated using pull-down assays. Furthermore, the cooperative actions of such a complex were systematically characterized. Besides, we evaluated the cross-functionality within LanBTC synthetase complexes from the nisin and subtilin systems. To solve the structure of the ABC transporter LanT, we developed an optimized two-step purification strategy and performed crystallization trials of two homologous transporters, i.e. NisT and SpaT. Overall, these comprehensive studies emphasize the crucial role of larger assemblies of multi-proteins during the lanthipeptide biosynthesis, and lay a foundation for further structural and functional characterization of the LanBTC complex

Analysis of cross-functionality within LanBTC synthetase complexes from different bacterial sources with respect to production of fully modified lanthipeptides

Lanthipeptides belong to a family of ribosomally synthesized and posttranslationally modified peptides (RiPPs) containing (methyl)lanthionine residues. Commonly, class I lanthipeptides are synthesized by a gene cluster encoding a precursor peptide (LanA), a biosynthetic machinery (LanBTC), a protease (LanP), a two-component regulatory system (LanRK), and an immunity system (LanI and LanFEG). Although nisin and subtilin are highly similar class I lanthipeptides, the cross-regulation by LanRK and the cross-immunity by LanI and LanFEG between the nisin and subtilin systems have been proven very low. Here, the possibility of the cross-functionality by LanBTC to modify and transport nisin precursor (NisA) and subtilin precursor (SpaS) was evaluated in Bacillus subtilis and Lactococcus lactis. Interestingly, we found that a promiscuous NisBC-SpaT complex is able to synthesize and export nisin precursor, as efficiently as the native nisin biosynthetic machinery NisBTC, in L. lactis, but not in B. subtilis. The assembly of the NisBC-SpaT complex at a single microdomain, close to the old cell pole, was observed by fluorescence microscopy in L. lactis. In contrast, such a complex was not formed in B. subtilis. Furthermore, the isolation of the NisBC-SpaT complex and its subcomplexes from the cytoplasmic membrane of L. lactis by pull-down assays was successfully conducted. Our work demonstrates that the association of LanBC with LanT is critical for the efficient biosynthesis and secretion of the lanthipeptide precursor with complete modifications, and suggests a cooperative mechanism between LanBC and LanT in the modification and transport processes. IMPORTANCE A multimeric synthetase LanBTC complex has been proposed for the in vivo production of class I lanthipeptides. However, it has been demonstrated that LanB, LanC, and LanT can perform their functionality in vivo and in vitro, independently of other Lan proteins. The role of protein-protein interactions, especially between the modification complex LanBC and the transport system LanT, in the biosynthesis process of lanthipeptides is still unclear. In this study, the importance of the presence of a well-installed LanBTC complex in the cell membrane for lanthipeptide biosynthesis and transport was reinforced. In L. lactis, the recruitment of SpaT from the peripheral cell membrane to the cell poles by the NisBC complex was observed, which may explain the mechanism by which secretion of premature peptide is prevented

Floquet Nonadiabatic Nuclear Dynamics with Photoinduced Lorenz-Like Force in Quantum Transport

In our recent paper [Mosallanejad et al., Phys. Rev. B 107(18), 184314, 2023], we have derived a Floquet electronic friction model to describe nonadiabatic molecular dynamics near metal surfaces in the presence of periodic driving. In this work, we demonstrate that Floquet driving can introduce an anti-symmetric electronic friction tensor in quantum transport, resulting in circular motion of the nuclei in the long time limit. Furthermore, we show that such a Lorentz-like force strongly affects nuclear motion: at lower voltage bias, Floquet driving can increase the temperature of nuclei; at larger voltage bias, Floquet driving can decrease the temperature of nuclei. In addition, Floquet driving can affect electron transport strenuously. Finally, we show that there is an optimal frequency that maximizes electron current. We expect that the Floquet electronic friction model is a powerful tool to study nonadiabatic molecular dynamics near metal surfaces under Floquet driving in complex systems

Dyslipidemia and the Prevalence of Hypertension: A Cross-Sectional Study Based on Chinese Adults Without Type 2 Diabetes Mellitus

Background: In clinical practice, it is frequently observed that patients with hypertension often coexist with dyslipidemia. However, studies on atherosclerotic indices and the prevalence of hypertension are still limited. The purpose of this study was to assess the relationship between atherosclerotic indices and the prevalence of hypertension in Chinese adults without type 2 diabetes mellitus. Methods: In this paper, a cross-sectional study was conducted based on 117,056 adults in 11 Chinese cities (Shanghai, Beijing, Wuhan, Suzhou, Shenzhen, Changzhou, Nantong, Guangzhou, Hefei, Nanjing, and Chengdu) from 2010 to 2016. Besides, the raw data was obtained from the public database (www.Datadryad.org), while eight atherosclerosis indices namely the atherogenic coefficient (AC), Castelli's risk index I (CRI-I) and II (CRI-II), the atherogenic index of plasma (AIP), the cholesterol index, the lipoprotein combined index (LCI), non-high-density lipoprotein cholesterol (non-HDL-C) and triglycerides/high-density lipoprotein cholesterol (TG/HDL-C) were analyzed in this study. Apart from that, two groups of continuous variables were measured using the Mann-Whitney test, and categorical variables were analyzed using the Chi-square test. Differences between multiple groups of continuous variables were investigated using Kruskal-Wallis one-way analysis of variance (ANOVA) and Dunn's test. Furthermore, Spearman correlation analysis and multivariate logistic regression analyses were performed to assess the relationship between atherosclerotic indices and blood pressure levels, and the prevalence of hypertension, respectively. The results of multivariate logistic regression analyses were expressed as the odds ratio (OR) and their corresponding 95% confidence intervals (CIs). Moreover, the receiver operating characteristic (ROC) curve was depicted to further analyze the predictive value of the atherosclerotic indices on the prevalence of hypertension. Results: The atherosclerosis indices were higher in the hypertensive population compared to those in the normotensive population. Meanwhile, systolic blood pressure (SBP) and diastolic blood pressure (DBP) were linearly and positively correlated with atherosclerotic indices. In addition, multivariate logistic regression analysis showed that the cholesterol index and non-HDL-C were observed to be positively associated with the prevalence of hypertension (p for trend < 0.05). Moreover, the prevalence of hypertension increased by 3.7% (OR: 1.037; 95% CI: 1.009-1.065; p = 0.009) and 6.1% (OR: 1.06; 95% CI: 1.033-1.091; p < 0.001), respectively, as per 1-standard deviation (SD) increase in the cholesterol index and non-HDL-C. Beyond that, ROC analysis demonstrated that the cholesterol index and non-HDL-C have a good predictive value for the prevalence of hypertension in women, with under the ROC curve (AUC) of 0.659 and 0.684 and cut-off values of 47.94 and 134.34 mg/dl, accordingly. Conclusions: In Chinese adults without type 2 diabetes mellitus, atherosclerotic indices were significantly higher in hypertensive populations compared with those in normotensive populations, regardless of hypertension levels. Meanwhile, SBP and DBP were linearly and positively related to atherosclerotic indices. Besides, the cholesterol index and non-HDL-C were independent risk factors for the prevalence of hypertension, and they could be adopted for effectively predicting the prevalence of hypertension in women

Cash dividends, return on equity and earnings persistence

With reference to Ohlson’ model, we optimise earnings persistence model and express earnings persistence measure as a function of return on equity (R.O.E.), dividends payout ratio and other factors. Our theoretical model reveals that dividends payout ratio has little effect on the earnings persistence, while R.O.E. has a decisive effect on earnings persistence. Using quarterly earnings data of 872 listed firms in China over 2011–2020, we calculate the Revised Persistence value of earnings (RPer value) of our earnings persistence model, and find that the Rper value of our model have more explanatory power than that of Kormendi and Lipe’ model. Our study also suggest that quarterly earnings are useful and have information content. Both the theoretical model and empirical results of our research are of great significance to understand and support the implementation of semi-compulsory cash dividends rules in China

Floquet driven frictional effects

When the coupled electron-nuclear dynamics are subjected to strong Floquet driving, there is a strong breakdown of the Born-Oppenheimer approximation. In this article, we derive a Fokker-Planck equation to describe non-adiabatic molecular dynamics with electronic friction for Floquet driven systems. We first provide a new derivation of the Floquet quantum-classical Liouville equation (QCLE) for driven electron-nuclear dynamics. We then transform the Floquet QCLE into a Fokker-Planck equation with explicit forms of frictional force and random force. We recast the electronic friction in terms of Floquet Green's functions such that we can evaluate the electronic friction explicitly. We show that the Floquet electronic friction tensor exhibits antisymmetric terms even at equilibrium for real-valued Hamiltonian, suggesting that there is a Lorentz-like force in Floquet driven non-Born Oppenheimer dynamics even without any spin-orbit couplings.Comment: Main: 5 pages, 3 figuers, Supplement: 5 pag

The evolving evidence base for child protection in Chinese societies

Child maltreatment is a substantial public health problem worldwide. Although extensively studied in Western countries, until recently little systematic research had been published about the situation in the world's most populous nation and ethnic diaspora. In this review, we examine trends from community-based research with Chinese young people and parents in mainland China, Hong Kong SAR, Taiwan, Singapore, and Malaysia. It is clear that many Chinese adolescents experience a substantial burden from various forms of maltreatment and the psychological and behavioral correlates are similar to those found in other cultures. However, the research reveals a large gap between this reality and Chinese adults' perceptions about emotional, physical, and sexual abuse. Comprehensive awareness programs are needed to close this information gap and thereby mobilize support for prevention and care initiatives

Visualization and Analysis of the Dynamic Assembly of a Heterologous Lantibiotic Biosynthesis Complex in Bacillus subtilis

A membrane-associated lanthipeptide synthetase complex, consisting of the dehydratase NisB, the cyclase NisC, and the ABC transporter NisT, has been described for nisin biosynthesis in the coccoid bacterium Lactococcus lactis. Here, we used advanced fluorescence microscopy to visualize the functional nisin biosynthesis machinery in rod-shaped cells and analyzed its spatial distribution and dynamics employing a platform we developed for heterologous production of nisin in Bacillus subtilis. We observed that NisT, as well as NisB and NisC, were all distributed in a punctate pattern along the cell periphery, opposed to the situation in coccoid cells. NisBTC proteins were found to be highly colocalized, being visualized at the same spots by dual fluorescence microscopy. In conjunction with the successful isolation of the biosynthetic complex NisBTC from the cell membrane, this corroborated that the visual bright foci were the sites for nisin maturation and transportation. A strategy of differential timing of expression was employed to demonstrate the in vivo dynamic assembly of NisBTC, revealing the recruitment by NisT of NisBC to the membrane. Additionally, by use of mutated proteins, the nucleotide binding domain (NBD) of NisT was found to function as a membrane anchor for NisB and/or NisC. We also show that the nisin biosynthesis sites are static and likely associated with proteins residing in lipid rafts. Based on these data, we propose a model for a three-phase production of modified precursor nisin in rod-shaped bacteria, presenting the assembly dynamics of NisBTC and emphasizing the crucial role of NisBC, next to NisT, in the process of precursor nisin translocation. IMPORTANCE Nisin is a model antimicrobial peptide for LanBC-modified lantibiotics that are modified and transported by a membrane synthetase complex. Although the subcellular localization and the assembly process of such a complex in L. lactis have been described in our recent work (J. Chen, A. J. van Heel, and O. P. Kuipers, mBio 11:e02825-20, 2020, https://doi.org/10.1128/mBio.02825-20), it proved difficult to gain a more detailed insight into the exact LanBTC assembly in the L. lactis system. Rod-shaped cells, especially B. subtilis, are better suited to study the assembly dynamics of these protein complexes. In this work, we present evidence for the existence of the lanthipeptide biosynthetic complex by visualizing and isolating the machinery in vivo. The dynamic behavior of the modification machinery and the transporter within the cells was characterized in depth, revealing the dependence of first LanB and LanC on each other and subsequent recruitment of them by LanT during the machinery assembly. Importantly, the elucidation of the dynamic assembly of the complex will facilitate future studies of lanthipeptide transport mechanisms and the structural characterization of the complete complex