Biology subjects

Zemlianski, V.

Publications and source records attributed to Zemlianski, V..

4 recordsLinked to original sources

bioRxiv2024

Cbf11 and Mga2 function as a single regulatory entity to activate transcription of lipid metabolism genes and promote mitotic fidelity in fission yeast

Within a eukaryotic cell, both lipid homeostasis and faithful cell cycle progression are meticulously orchestrated. The fission yeast Schizosaccharomyces pombe provides a powerful platform to study the intricate regulatory mechanisms governing these fundamental processes. In S. pombe, the Cbf11 and Mga2 proteins are transcriptional activators of non-sterol lipid metabolism genes, with Cbf11 also known as a cell cycle regulator. Despite sharing a common set of target genes, little was known about their functional relationship. This study reveals that Cbf11 and Mga2 function together as a single regulatory entity critical for both lipid metabolism and mitotic fidelity. Deletion of either gene results in a similar array of defects, including slow growth, dysregulated lipid homeostasis, impaired cell cycle progression (cut phenotype), abnormal cell morphology, perturbed transcriptomic and proteomic profiles, and compromised response to the stressors camptothecin and thiabendazole. Remarkably, the double deletion mutant does not exhibit a more severe phenotype compared to the single mutants, suggesting that Cbf11 and Mga2 work together in the same pathway. In addition, ChIP-nexus analysis reveals that both Cbf11 and Mga2 bind to nearly identical positions within the promoter regions of target genes. Interestingly, Mga2 binding appears to be dependent on the presence of Cbf11 and Cbf11 likely acts as a tether to DNA, while Mga2 is needed to activate the target genes. In addition, the study explores the distribution of Cbf11 and Mga2 homologs across fungi. The presence of both Cbf11 and Mga2 homologs in Basidiomycota contrasts with Ascomycota, which mostly lack Cbf11 but retain Mga2. This suggests an evolutionary rewiring of the regulatory circuitry governing lipid metabolism and mitotic fidelity. In conclusion, this study offers compelling support for Cbf11 and Mga2 functioning jointly as a single regulator of lipid metabolism and mitotic fidelity in fission yeast. SUMMARY STATEMENTCbf11 and Mga2, transcriptional activators of non-sterol lipid metabolism genes, function as a single regulatory unit and are both required for proper cell cycle progression in the fission yeast Schizosaccharomyces pombe.

molecular biology↗

bioRxiv2023

Nitrogen availability and TOR signalling are important for preventing catastrophic mitosis in fission yeast

Mitosis is a critical stage in the cell cycle, controlled by a vast network of regulators responding to multiple internal and external factors. The fission yeast Schizosaccharomyces pombe may demonstrate catastrophic mitotic phenotypes due to mutations or drug treatments. One of the factors provoking catastrophic mitosis is a disturbed lipid metabolism, resulting from e.g. mutations in acetyl-CoA/biotin carboxylase (cut6), in fatty acid synthase (fas2/lsd1), or in the transcriptional regulator of lipid metabolism (cbf11) genes, as well as treatment with inhibitors of fatty acid synthesis. It was previously shown that mitotic fidelity in lipid metabolism mutants can be partially rescued by ammonium chloride. In this study we demonstrate that mitotic fidelity can be improved by multiple good nitrogen sources. Moreover, this rescue is not limited to lipid metabolism disturbances but also applies to a number of unrelated mitotic mutants. Interestingly, the rescue is not achieved by restoring the lipid metabolism state, but rather indirectly. We found that the TOR regulatory network plays a major role in mediating such rescue, highlighting a novel role for TOR in mitotic fidelity.

cell biology↗

bioRxiv2023

Critical importance of DNA binding for CSL protein functions in fission yeast

CSL (CBF1/RBP-J{kappa}/Suppressor of Hairless/LAG-1) proteins are conserved transcription factors found in animals and fungi. In fission yeast, they regulate various cellular processes, including cell cycle progression, lipid metabolism, and cell adhesion. CSL proteins bind to DNA through their N-terminal Rel-like domain and central beta-trefoil domain. Here, we investigated the importance of DNA binding for CSL functions in the fission yeast Schizosaccharomyces pombe. We created CSL mutants with disrupted DNA binding and found that the vast majority of CSL functions depend on intact DNA binding. Specifically, DNA binding is crucial for the regulation of cell adhesion, lipid metabolism, cell cycle progression, long non-coding RNA expression, and genome integrity maintenance. Interestingly, perturbed lipid metabolism leads to chromatin structure changes, potentially linking lipid metabolism to the diverse CSL-associated phenotypes. Our study highlights the critical role of DNA binding for CSL protein functions in fission yeast. SUMMARY STATEMENTCSL transcription factors regulate a diverse set of processes, but the mechanisms are not always clear. We show that S. pombe CSL proteins need the ability to bind DNA for most of their roles.

molecular biology↗

bioRxiv2021

NAD+ capping of RNA in Archaea and Mycobacteria

Chemical modifications of RNA affect essential properties of transcripts, such as their translation, localization and stability. 5-end RNA capping with the ubiquitous redox cofactor nicotinamide adenine dinucleotide (NAD+) has been discovered in organisms ranging from bacteria to mammals. However, the hypothesis that NAD+ capping might be universal in all domains of life has not been proven yet, as information on this RNA modification is missing for Archaea. Likewise, this RNA modification has not been studied in the clinically important Mycobacterium genus. Here, we demonstrate that NAD+ capping occurs in the archaeal and mycobacterial model organisms Methanosarcina barkeri and Mycobacterium smegmatis. Moreover, we identify the NAD+-capped transcripts in M. smegmatis, showing that this modification is more prevalent in stationary phase, and revealing that mycobacterial NAD+-capped transcripts include non-coding small RNAs, such as Ms1. Furthermore, we show that mycobacterial RNA polymerase incorporates NAD+ into RNA, and that the genes of NAD+-capped transcripts are preceded by promoter elements compatible with {sigma}A/{sigma}F dependent expression. Taken together, our findings demonstrate that NAD+ capping exists in the archaeal domain of life, suggesting that it is universal to all living organisms, and define the NAD+-capped RNA landscape in mycobacteria, providing a basis for its future exploration.

molecular biology↗