Biology subjects

Dittmann, A.

Publications and source records attributed to Dittmann, A..

3 recordsLinked to original sources

bioRxiv2022

Structure of a volume-regulated heteromeric LRRC8A/C channel

Volume-regulated anion channels participate in the cellular response to osmotic swelling. These heteromeric membrane proteins consist of LRRC8 family members, where the subunit composition determines permeation properties. Although structures of the obligatory LRRC8A subunit have previously defined the architecture of VRACs, the organization of heteromeric channels has remained elusive. Here we have closed this gap by the structural characterization of channels consisting of LRRC8A and LRRC8C. Like homomeric LRRC8A, these proteins assemble as hexamers. Despite twelve possible arrangements, we find a single predominant organization with an A:C ratio of two. In this assembly, four LRRCA subunits cluster in their preferred conformation observed in homomers as pairs of closely interacting proteins that stabilize a closed state of the channel. In contrast, the two interacting LRRC8C subunits show a larger flexibility, underlining their role in the destabilization of the tightly packed A subunits, thereby enhancing the activation properties of the protein.

biochemistry↗

bioRxiv2022

Deciphering of BTH-induced response of tomato (Solanum lycopersicum L.) and its effect on plant virus infection through the multi-omics approach

One of the preventive methods used to limit the losses caused by viruses is the application of synthetic immunity inducers, such as benzo(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH). This study aimed to explain how the BTH treatment affects the defence and developmental processes in tomato plants (Solanum lycopersicum L.) as well as plant response to virus infection. The comparative multi-omics analyses of tomato plants treated with BTH were performed, including transcriptomics (RNA-seq), proteomics (Liquid Chromatography-Mass Spectrometry), and metabolomics (targeted hormonal analysis). To confirm the priming effect of BTH on tomato resistance, the plants were infected with tomato mosaic virus (ToMV) seven days post-BTH treatment. The combined functional analysis indicated the high impact of BTH on the plants developmental processes and activation of the immune response early after the treatment. In the presented experimental model, the increased level of WRKY TRANSCRIPTION FACTORS, ARGONAUTE 2A, thiamine and glutathione metabolism, cell wall reorganization, and detoxification processes, as well as accumulation of three phytohormones: abscisic acid, jasmonic-isoleucine (JA-Ile), and indole-3-carboxylic acid (I3CA), were observed upon BTH application. The immune response activated by BTH was related to increased expression of genes associated with the cellular detoxification process, systemic acquired resistance, and induced systemic resistance as well as post-transcriptional gene silencing. Increased levels of I3CA and JA-Ile might explain the BTHs effectiveness in the induction of the plant defence against a broad spectrum of pathogens. For the first time, the BTH impact on the thiamine metabolism was revealed in tomatoes.

plant biology↗

bioRxiv2022

A DARPin-based molecular toolset to probe gephyrin and inhibitory synapse biology

Neuroscience currently requires the use of antibodies to study synaptic proteins, where antibody binding is used as a correlate to define the presence, plasticity, and regulation of synapses. Gephyrin is an inhibitory synaptic scaffolding protein used to mark GABAergic and glycinergic postsynaptic sites. Despite the importance of gephyrin in modulating inhibitory transmission, its study is currently limited by the tractability of available reagents. Designed Ankyrin Repeat Proteins (DARPins) are a class of synthetic protein binder derived from diverse libraries by in vitro selection, and tested by high-throughput screening to produce specific binders. In order to generate a functionally diverse toolset for studying inhibitory synapses, we screened a DARPin library against gephyrin mutants representing both phosphorylated and dephosphorylated states. We validated the robust use of anti-gephyrin DARPin clones for morphological identification of gephyrin clusters in rodent neuron culture and brain tissue, discovering previously overlooked clusters. This DARPin-based toolset includes clones with heterogenous gephyrin binding modes that allowed for identification of the most extensive gephyrin interactome to date, and defined novel classes of putative interactors, creating a framework for understanding gephyrins non-synaptic functions. This study demonstrates anti-gephyrin DARPins as a versatile platform for studying inhibitory synapses in an unprecedented manner.

neuroscience↗