Role of a bacterial dynamin-like protein DynA in resistance to environmental stress response

Many bacterial species contain dynamin-like proteins (DLPs). DLPs show a high level of functional diversification. DynA in Bacillus subtilis is a two-headed DLP, mediating nucleotide-independent membrane tethering in vitro and contributing to the innate immunity of bacteria against membrane stress and phage infection. However, so far, the functional mechanisms of the bacterial DLP are poorly understood. Here, the biochemical characteristics of DynA-induced membrane fusion, the mechanisms of DynA-mediated phage resistance and protection effect to antibiotic treatment. To uncover the biochemical characteristics of DynA-induced membrane fusion, we employed content mixing and lipid mixing assays in reconstituted systems to study if DynA induces membrane full fusion. Further, the individual contribution of its subunits in membrane fusion and the role of GTP hydrolysis of DynA were analysed in detail. Our results based on fluorescence resonance energy transfer (FRET) indicated that DynA could induce aqueous content mixing even in the absence of GTP. Moreover, DynA-induced membrane fusion in vitro was a thermo-promoted slow response and showed phospholipid preferences. The D1 subunit of DynA was crucial for membrane fusion, whereas it cannot stabilize the tethered membrane without the help of the D2 subunit. At low temperatures, GTPase activity promoted dissociation of membrane clusters induced by DynA. Surprisingly, the digestion of DynA after hemifusion mediated an instant rise of content exchange, supporting the assumption that disassembly of DynA is the elemental power for fusion-through-hemifusion. Next, the role of DynA in phage resistance was analyzed. We found that the presence of DynA could delay cell lysis after phage infection, thereby slowing down the release of phage progeny from the host cells. During the process, DynA formed static clusters on the cell membrane. It seems that DynA supports the cell membrane and delays rupture. Using transmission electron microscopy (TEM), the protein structure of DynA in solution was analyzed. DynA likely formed dimers and trimers, showing a four-corner and hexagonal shape. In a screening approach, we searched for novel genes that could have a role in phage defence. A B. subtilis 168 single-gene deletion library was screened. DagK and ypmB were found to be related to bacteriophage resistance. The presence of DagK can help bacteria resist phage attachment, replication, and host cell lysis. And the role of YpmB against bacteriophages needs to be further verified and characterized.Viele Bakterienarten enthalten Dynamin-ähnliche Proteine (DLPs). DLPs weisen ein hohes Maß an funktionaler Diversifikation auf. DynA in Bacillus subtilis ist ein zweiköpfiges DLP, das in vitro die nukleotidunabhängige Membranbindung vermittelt und zur angeborenen Immunität von Bakterien gegen Membranstress und Phageninfektion beiträgt. Bisher sind die Funktionsmechanismen des bakteriellen DLP jedoch kaum bekannt. Hier wurden die biochemischen Eigenschaften der DynA-induzierten Membranfusion, die Mechanismen der DynA-vermittelten Phagenresistenz und die Schutzwirkung gegen Antibiotika in Detail untersucht. Um die biochemischen Eigenschaften der DynA-induzierten Membranfusion aufzudecken, verwendeten wir Inhaltsmischungs- und Lipidmischungsassays in rekonstituierten Systemen, um zu untersuchen, ob DynA die vollständige Membranfusion induziert. Ferner wurden der individuelle Beitrag seiner Untereinheiten zur Membranfusion und die Rolle der GTP-Hydrolyse von DynA detailliert analysiert. Unsere Ergebnisse basierend auf dem Fluoreszenzresonanzenergietransfer (FRET) zeigten, dass DynA selbst in Abwesenheit von GTP eine Vermischung des Liposomeninhalts induzieren kann. Darüber hinaus war die DynA-induzierte Membranfusion in vitro eine thermisch geförderte langsame Reaktion und zeigte Phospholipidpräferenzen. Die D1-Untereinheit von DynA war entscheidend für die Membranfusion, wohingegen sie die angebundene Membran ohne die Hilfe der D2-Untereinheit nicht stabilisieren kann. Bei niedrigen Temperaturen förderte die GTPase-Aktivität die Dissoziation von durch DynA induzierten Membranclustern. Überraschenderweise vermittelte der Verdau von DynA nach der Hemifusion einen sofortigen Anstieg des Inhaltsaustauschs, was die Annahme stützt, dass die Zerlegung von DynA die elementare Kraft für die Fusion durch Hemifusion ist. Als nächstes wurde die Rolle von DynA bei der Phagenresistenz analysiert. Wir fanden heraus, dass das Vorhandensein von DynA die Zelllyse nach einer Phageninfektion verzögern und dadurch die Freisetzung von Phagennachkommen aus den Wirtszellen verlangsamen kann. Während des Prozesses bildete DynA statische Cluster auf der Zellmembran. Es scheint, dass DynA die Zellmembran unterstützt und den Bruch verzögert. Unter Verwendung eines Transmissionselektronenmikroskops (TEM) wurde die Proteinstruktur von DynA in Lösung analysiert. DynA bildete wahrscheinlich Dimere und Trimere, die eine viereckige und sechseckige Form zeigten. In einem Screening-Ansatz suchten wir nach neuen Genen, die eine Rolle bei der Phagenabwehr spielen könnten. Eine B. subtilis 168-Einzelgen-Deletionsbibliothek wurde gescreent. Es wurde festgestellt, dass dagK und ypmB mit der Bakteriophagenresistenz zusammenhängen. Das Vorhandensein von DagK kann Bakterien helfen, die Anhaftung, und die Replikation zu behindern. Zudem wird die Lyse von Wirtszellen vermindert. Und die Rolle von YpmB gegen Bakteriophagen muss weiter verifiziert und charakterisiert werden

Study on the WeChat-Based After-Class Translation Teaching Mode of College English From the Perspective of Eco-Translatology

This paper intends to verify the feasibility of WeChat-based after-class translation teaching of college English from the perspective of eco-translatology. It believes that the limitation of time and space should be broken and views the students as its center during the process of translation teaching. The result of three-month experiment has proved that the new mode is feasible and effective in enhancing students’ translation competence

Modelling of sediment transport and bed deformation in rivers with continuous bends

Peer reviewedPostprin

An Investigation into the Current State and Direction of the Development of the Russian Language as a Specialty in China’s Comprehensive Universities

Chinese comprehensive universities will face the stern tenet of the development of Russian as a specialty. Connecting this specialty with the advantage of the development of university disciplines and taking one’s own path of building the Russian language specialty using one’s own know-hows and accomplishments is an important issue instructors of Russians are going to have to tackle. This article analyzes the major tenet of the development of the Russian language specialty in comprehensive universities. The article provides the author’s speculations and proposes a countermeasure in respect of the development of the Russian language specialty in comprehensive universities, which, the author hopes, will help the cause of the development of the Russian language specialty in comprehensive universities

The Image of Digital China in the Russian Media

The texts published in the Russian mass media on the digitalization processes in China are analysed in the article. The relevance of the study is due to the attention of the Chinese government to the implementation of international cooperation with various countries, including Russia. It is noted that the “Chinese theme” is one of the most relevant in Russian publications. Attention is paid to one of the most popular and dynamically developing areas — digitalization. The author proceeds from the assumption that the media not only reflect news information, but also in a certain way form ideas about a particular object being described. The author notes that significant attention is paid to the development of digitalization in the PRC in Russian newspapers and magazines. It is shown that in the publications of the Russian media, China is represented by one of the world leaders in digitalization, which is supported by the state and its citizens. The contexts, indicating that digitalization is penetrating into different spheres of the country’s life: education, industry, trade, etc., are given. The author comes to the conclusion that an exclusively positive image of digital China is being constructed in the Russian media

Combined Single-molecule Photon-stamping Spectroscopy And Femtosecond Transient Absorption Spectroscopy Studies Of Interfacial Electron Transfer Dynamics

The inhomogeneous interfacial electron transfer (IET) dynamics of 9-phenyl-2,3,7-trihydroxy-6-fluorone (PF)-sensitized TiO2 nanoparticles (NPs) has been probed by a single-molecule photon-stamping technique as well as ensemble-averaged femtosecond transient absorption spectroscopy. The forward electron transfer (FET) time shows a broad distribution at the single-molecule level, indicating the inhomogeneous interactions and ET reactivity of the PF/TiO2 NP system. The broad distribution of the FET time is measured to be 0.4 ± 0.1 ps in the transient absorption and picoseconds to nanoseconds in the photon-stamping measurements. The charge recombination time, having a broad distribution at the single-molecule level, clearly shows a biexponential dynamic behavior in the transient absorption: a fast component of 3.0 ± 0.1 ps and a slow component of 11.5 ± 0.5 ns. We suggest that both strong and weak interactions between PF and TiO2 coexist, and we have proposed two mechanisms to interpret the observed IET dynamics. A single-molecule photon-stamping technique and ensemble-averaged transient absorption spectroscopy provide efficient “zoom-in” and “zoom-out” approaches for probing the IET dynamics. The physical nature of the observed multiexponential or stretched-exponential ET dynamics in the ensemble-averaged experiments, often associated with dynamic and static inhomogeneous ET dynamics, can be identified and analyzed by single-molecule spectroscopy measurements