Biology subjects

Cieslak, D.

Publications and source records attributed to Cieslak, D..

3 recordsLinked to original sources

bioRxiv2025

NT-C2-Dependent Phosphoinositide Binding Controls PLASTID MOVEMENT IMPAIRED1 Localization and Function

Plants respond to changing environmental conditions through rapid cellular mechanisms, one of which is light-induced chloroplast movement. Plastid Movement Impaired 1 (PMI1) is one of the proteins involved in this process that undergoes rapid, blue light-dependent relocalization within the plasma membrane. Here, we investigate the molecular determinants of PMI1 membrane association. We identify the NT-C2 domain as the principal membrane-binding module and show that it extends beyond the boundaries previously assigned to the C2 domain. Plasma membrane localization is mediated by interactions between the extended NT-C2 domain and the phosphoinositides phosphatidylinositol 4-phosphate (PI4P) and phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2], with basic residues within this region being essential for PMI1 membrane binding. We further demonstrate that the NT-C2 domain binds Ca2+ in vitro and that calcium availability modulates its phosphoinositide-binding preference. Consistently, depletion of cytosolic Ca2+ or inhibition of Ca2+ fluxes abolished the blue light-induced redistribution of PMI1 within the plasma membrane. Finally, we show that the extended NT-C2 domain, together with its flanking intrinsically disordered regions, is indispensable for PMI1 function in chloroplast movement regulation.

plant biology↗

bioRxiv2025

SnRK2.4 and SnRK2.10 redundantly control developmental leaf senescence by sustaining ABA production and signaling

Plants constantly and precisely control their growth by inducing distinct developmental programs to survive and produce high-quality offspring in the changing environment. The fine-tuning of the development according to endogenous and environmental signals requires exact intercellular signaling and a balanced response. Kinases of the Sucrose non-fermenting-1-Related protein Kinases type 2 (SnRK2s) family primarily take part in the response and adaptation to environmental stress factors. Notably, here we show that two ABA-non-activated SnRK2s, SnRK2.4 and SnRK2.10, are also activated in non-stress conditions in developmentally senescing leaves of Arabidopsis thaliana. Phenotypic, biochemical, and molecular analyses performed on single snrk2.4 or snrk2.10, and double snrk2.4/2.10 kinase mutants showed that SnRK2.4 and SnRK2.10, acting redundantly, promote developmental leaf senescence. Further, SnRK2.4 and SnRK2.10 enhance ABA accumulation in senescing leaves by inducing NCED2, one of key ABA biosynthesis-related genes. The two kinases induce developmental leaf senescence by modulating the expression of multiple ABA-responsive, osmotic stress, and senescence-related genes, such as the senescence master regulators ORE1, ORS1, WRKY33, WRKY75, and ANAC087. Furthermore, we show that SnRK2.4 and SnRK2.10 act upstream of MAPK signaling by enhancing the expression and activity of MAPKKK18, a senescence-inducing kinase. These results document a new regulatory function of SnRK2.4 and SnRK2.10: they are activated in Arabidopsis leaves in response to endogenous signals and redundantly induce developmental leaf senescence by stimulating ABA production and sustaining major ABA-dependent and -independent signaling pathways.

plant biology↗

bioRxiv2023

Phosphorylation Promotes Liquid-Liquid Phase Separation of GRP8 and Its Assembly into Stress Granules Upon Salinity Stress in Arabidopsis

Drought and salinity are major environmental stresses affecting plant development and growth. SNF1-related protein kinases type 2 (SnRK2s) are key regulators of the plant responses to water deficit and salt stress. Here, we show that Arabidopsis thaliana Glycine-Rich RNA-Binding Protein 8 (GRP8) is a target of abscisic acid (ABA)-non-activated SnRK2s and negatively regulates root growth and seed germination under salt stress. In response to salinity, GRP8 assembles into stress granules (SGs). We show that in addition to the GRP8 C-terminal glycine-rich intrinsically disordered region (IRD), the N-terminal RNA recognition motif (RRM) plays a key role in this process. Phosphorylation of S27 in the RRM by SnRK2s significantly affects the structural dynamics of GRP8, facilitates its dimerization and subsequent liquid-liquid phase separation. Thus, we show that in addition to the known role of IDRs in recruitment into SGs, the RRM plays a decisive role.

plant biology↗