Zemlianski, V. | Search bioRxiv

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↗