Biology subjects

Szewc, L.

Publications and source records attributed to Szewc, L..

6 recordsLinked to original sources

bioRxiv2025

Chromatin retained MUSHER lncRNA integrates ABA and DOG1 signalling pathways to enhance Arabidopsis seeds dormancy.

Many plant lncRNAs regulate gene expression by binding to chromatin, but how they are retained at the target loci is unclear. We identify a new, chromatin-localized lncRNA - MUSHER, which activates two parallel regulatory pathways to increase Arabidopsis seed dormancy. MUSHER is upregulated in response to high temperatures, contributing to the induction of secondary dormancy. It promotes DOG1 expression by recruitment of the CPSF complex to enhance the proximal cleavage and polyadenylation at the DOG1 gene. It also increases ABA sensitivity in seeds by activating PIR1 gene transcription. These genes, located on different chromosomes, are both bound by MUSHER, despite lacking sequence homology. The chromatin association of MUSHER enables the integration of the DOG1-and ABA pathways to adjust seed germination timing. Additionally, MUSHER and other lncRNAs interact with U1 snRNP, which is required for their chromatin localisation, revealing a novel function of U1 snRNP in plants.

molecular biology↗

bioRxiv2024

Toss GERALT into chloroplast to make it green: a new regulator of chloroplast biogenesis and chlorophyll biosynthesis

Proteins belonging into cryptochrome/photolyase family act as either blue light photoreceptors or as enzymes responsible for repair of pyrimidine dimers produced under UV. Surprisingly, the members of plant-specific photolyase/blue-light receptor 2 (PPL/PHR2) subclade of this family, are almost completely uncharacterized. Here, we focused on the physiological role of protein encoded by Arabidopsis At2g47590 gene. Our results demonstrate for the first time its crucial role in cotyledon greening and maintenance of plant fitness. Based on the phenotype of the mutant in At2g47590 gene i.e. albino cotyledons and pale green true leaves we named this gene GERALT (GERMINATION ALBINO TRANSIENT). Using different approach including analysis of plant phenotypes, chloroplast sizes and architecture, transcriptomes, photosynthetic pigments, maximum PSII quantum yield (FV/FM) we show that the proper plant functioning is the effect of co-operation of GERALT-dependent and -independent pathways with the role of the former diminishing with plant age. Lower levels of transcripts dependent on plastid encoded polymerase and higher levels of these dependent on nuclear encoded polymerase, smaller chloroplasts with large grana stacks and very weakly developed stromal thylakoids, lower levels of photosynthetic pigments with higher chlorophyll a/b ratio, are among characteristic features of geralt plants. We believe that these results encourage scientific community to study PPL/PHR2 proteins which seems to play a special role in plants.

plant biology↗

bioRxiv2024

Plant Cleavage Factor I complex is essential for precise cleavage and polyadenylation site determination

Cleavage factor I (CFI) is a four-subunit protein complex of the pre-mRNA 3 end processing machinery in eukaryotes. In Arabidopsis, AtCFI25a, AtCFI25b, AtCFI59, and AtCFI68 have been identified as potential components of AtCFI, in silico. Here, we show that the AtCFI25a, AtCFI59, and AtCFI68 proteins each pulled down all components of the CFI, confirming that these subunits form the plant CFI complex. Furthermore, either AtCFI59 or AtCFI68 was essential for nuclear localization of the smallest subunit, AtCFI25a. Mutants with single loss-of-function for AtCFI59 or AtCFI68 showed no obvious morphological defects compared to wild-type plants, while the double mutant displayed pleiotropic morphological defects, identical to those previously reported for AtCFI25a loss-of-function plants. Moreover, these morphological defects correlated with alterations in the usage of 3 UTR cleavage and polyadenylation sites. atcfi25a, atcfi25a atcfi25b and atcfi59 atcfi68 double mutants showed widespread changes in the choice of cleavage and polyadenylation sites. In most cases, more proximal cleavage and polyadenylation sites were used, leading to shorter 3 UTRs. In particular, genes involved in light intensity, light harvesting, photosynthesis and cold responses showed significant dependence on AtCFI function. Furthermore, transcripts coding for AtCFI subunits showed altered 3 end processing in these mutants, suggesting self-regulation function of AtCFI in plants.

molecular biology↗

bioRxiv2020

SERRATE interacts with the nuclear exosome targeting (NEXT) complex to degrade primary miRNA precursors in Arabidopsis

SERRATE/ARS2 is a conserved RNA effector protein involved in transcription, processing and export of different types of RNAs. In Arabidopsis, the best-studied function of SERRATE (SE) is to promote miRNA processing. Here, we report that SE interacts with the Nuclear Exosome Targeting (NEXT) complex, comprising the RNA helicase HEN2, the RNA binding protein RBM7 and one of the two zinc-knuckle proteins ZCCHC8A/ZCCHC8B. The identification of common targets of SE and HEN2 by RNA-seq supports the idea that SE cooperates with NEXT for RNA surveillance by the nuclear exosome. Among the RNA targets accumulating in absence of SE or NEXT are miRNA precursors. Loss of NEXT components results in the accumulation of pri-miRNAs without affecting levels of miRNAs, indicating that NEXT is, unlike SE, not required for miRNA processing. As compared to se-2, se-2 hen2-2 double mutants showed increased accumulation of pri-miRNAs, but partially restored levels of mature miRNAs and attenuated developmental defects. We propose that the slow degradation of pri-miRNAs caused by loss of HEN2 compensates for the poor miRNA processing efficiency in se-2 mutants, and that SE regulates miRNA biogenesis through its double contribution in promoting miRNA processing but also pri-miRNA degradation through the recruitment of the NEXT complex.

plant biology↗

bioRxiv2019

DRB1 as a mediator between transcription and microRNA processing

DRB1 (HYL1) is a double-stranded RNA binding protein involved in miRNA processing in plants. It is a core component of the Microprocessor complex and enhances the efficiency and precision of miRNA processing by DCL1 protein. In this work, we report a novel function of DRB1 protein in the transcription of MIR genes. DRB1 co-localizes with RNA Polymerase II and affects its distribution along MIR genes. Moreover, proteomic experiments revealed that DRB1 protein interacts with many transcription factors. Finally, we show that the action of DRB1 is not limited to MIR genes as it impacts expression of many other genes, majority of which are involved in plant response to light. These discoveries add DRB1 as another player of gene regulation at transcriptional level, independent of its role in miRNA biogenesis.

plant biology↗

bioRxiv2019

mRNA adenosine methylase (MTA) deposits m6A on pri-miRNAs to modulate miRNA biogenesis in Arabidopsis thaliana

m6A, one of the most abundant mRNA modifications, has been associated with various metabolic processes in plants. Here we show that m6A also plays a role in miRNA biogenesis in Arabidopsis thaliana. Significant reductions in plant m6A/MTA levels results in lower accumulation of miRNAs whereas pri-miRNA levels tend to be higher in such plants. m6A-IP Seq and MTA-GFP RIP were used to show that many pri-miRNAs are m6A methylated and are bound by MTA, further demonstrating that pri-miRNAs can also be substrates for m6A methylation by MTA. We report that MTA interacts with RNA Pol II, supporting the assumption that m6A methylation is a co-transcriptional process, and also identify TGH, a known miRNA biogenesis related protein, as a novel protein that interacts with MTA. Finally, reduced levels of miR393b may partially explain the strong auxin insensitivity seen in Arabidopsis plants with reduced m6A levels.

plant biology↗