Agnieszka Ludwikow

• dr hab. MBA
• Head of Department at Adam Mickiewicz University in Poznań

The ubiquitin/26S proteasome system (UPS) has been implicated in the regulation of many physiological processes including hormone signaling. The plant hormone abscisic acid (ABA) employs the UPS to control its own synthesis and signaling and to regulate stress response and tolerance. Among the known effectors of ABA signaling, the ABI1 (abscisic ac...

Mitogen-activated protein kinase (MAPK) modules play key roles in the transduction of environmental and developmental signals through phosphorylation of downstream signaling targets, including other kinases, enzymes, cytoskeletal proteins or transcription factors, in all eukaryotic cells. A typical MAPK cascade consists of at least three sequential...

Ethylene is an important plant hormone that controls growth, development, aging and stress responses. The rate-limiting enzymes in ethylene biosynthesis, the 1-aminocyclopropane-1-carboxylate synthases (ACSs), are strictly regulated at many levels, including posttranslational control of protein half-life. Reversible phosphorylation/dephosphorylatio...

The Philadelphia positive acute lymphoblastic leukemia (ALL BCR::ABL1 positive) is characterized by the presence of the t(9;22)(q34;q11) resulting in the formation of the BCR::ABL1 fusion, constant high cellular BCR-ABL1 tyrosine kinase activity, abnormal lymphoid cell proliferation and genetic instability of leukemic cells. Recently, great progres...

Ethylene is an important plant hormone whose production relies on the action of key enzymes, one of which is 1‐aminocyclopropane‐1‐carboxylate synthase (ACS). There are three classes of ACS, which are all partially regulated by degradation through the ubiquitin‐proteasome system (UPS), which regulates ethylene production. Arabidopsis has a single c...

Mitogen-activated protein kinase (MAPK) cascades are conserved signalling pathways that transduce extracellular signals into diverse cellular responses. Arabidopsis MAPKKK18 is a component of the MAP3K17/18-MKK3-MPK1/2/7/14 cascades, which play critical roles in ABA signalling, drought tolerance and senescence. A very important aspect of MAP kinase...

The Escherichia coli enzyme EcAIII catalyzes the hydrolysis of L‐Asn to L‐Asp and ammonia. Using a nature‐inspired mutagenesis approach, we designed and produced five new EcAIII variants (M200I, M200L, M200K, M200T, M200W). The modified proteins were characterized by spectroscopic and crystallographic methods. All new variants were enzymatically ac...

Abscisic acid (ABA) affects plant physiology by altering gene expression, enabling plants to adapt to a wide range of environments. Plants have evolved protective mechanisms to allow seed germination in harsh conditions. Here, we explore a subset of these mechanisms involving the AtBro1 gene, which encodes one of a small family of poorly characteri...

miRNAs are involved in various biological processes, including adaptive responses to abiotic stress. To understand the role of miRNAs in the response to ABA, ABA-responsive miRNAs were identified by small RNA sequencing in wild-type Arabidopsis, as well as in abi1td, mkkk17, and mkkk18 mutants. We identified 10 novel miRNAs in WT after ABA treatmen...

Type 2C protein phosphatases (PP2Cs) of group A play a significant role in the regulation of various processes in plants including growth, development, ion transport, and stress acclimation. In this study, we selected potential PP2C group A inhibitors using a structure-based virtual screening method followed by biochemical and in vitro validation....

Plant senescence is a highly regulated process that allows nutrients to be mobilized from dying tissues to other organs. Despite that senescence has been extensively studied in leaves, the senescence of ephemeral organs located underground is still poorly understood, especially in the context of phytohormone engagement. The present study focused on...

In contrast to aboveground organs (stems and leaves), developmental events and their regulation in underground organs, such as pioneer and fine roots, are quite poorly understood. The objective of the current study was to achieve a better understanding of the physiological and molecular role of reactive oxygen species (ROS) and ROS-related enzymes...

The remobilization and resorption of plant nutrients is considered as a crucial aspect of the seasonal senescence of plant organs. In leaves, the mechanisms responsible for the relocation of valuable compounds are well understood while the related processes in roots are still being debated. Some research indicates that remobilization in roots occur...

Regulation of gene expression, as determined by the genetics of the tree species, is a major factor in determining wood quality. Therefore, the identification of genes that play a role in xylogenesis is extremely important for understanding the mechanisms shaping the plant phenotype. Efforts to develop new varieties characterized by higher yield an...

In Arabidopsis, Group A Protein Phosphatases type 2C (PP2C) acts as an important regulators and effectors of the Abscisic acid pathway (ABA). The current knowledge about the catalytic mechanism of PP2Cs inactivation simplify the development of group A PP2C inhibitors. In our approach, we used modern Bioinformatics and Computational Chemistry method...

AtDeg2 is a chloroplast protein with dual protease/chaperone activity. Since data on how the individual activities of AtDeg2 affect growth and development of Arabidopsis thaliana plants is missing, two transgenic lines were prepared that express mutated AtDeg2 versions that have either only protease or chaperone activity and a comprehensive ontogen...

Increasing the drought tolerance of crops is one of the most challenging goals in plant breeding. To improve crop productivity during periods of water deficit, it is essential to understand the complex regulatory pathways that adapt plant metabolism to environmental conditions. Among various plant hormones and second messengers, calcium ions are kn...

Gene names and accession numbers.

Comparison of sequence similarity and identity between CPKs using SIAS method.

Phylogenetic relationship of selected plant calcium-dependent protein kinases. A neighbor-joining phylogenetic tree with 1000 bootstrap replications was generated with MEGA6 software using the full-length ORFs of 34 Arabidopsis (shown in red), 24 rice (green), and 24 barley (blue) CPK isoforms. Amino acid sequences were obtained from NCBI and align...

Proteins identified in His-HvCPK2a complexes.

Amino acid sequence identity (%) between AS1 and AS2 peptides and HvCPK sequence, respectively of the conserved residues of the active site located in kinase domain region. The HvCDPK2a protein selected for further analyses is highlighted in bold.

To identify drought-induced CPKs, we used custom-prepared antibodies (AS1 and AS2) against the conserved kinase domain. Antibodies were used to immunoprecipitate protein complexes containing CPKs from drought-treated barley. CPK enzyme activities associated with immune complexes were identified using an in vitro kinase assay. Myelin basic protein (...

Multiple sequence alignment.

MS/MS spectra of phosphopeptides in Table 1.

Subcellular localization of HvCPK2a in Arabidopsis protoplasts. The WT version of the HvCPK2a-GFP fusion protein is associated with the plasma membrane. HvCPK2aK94M-GFP is also present in the nucleus, while the HvCPK2aD189A variant is present in the cytoplasm and on the cytoplasmic side of the plasma membrane. Hoechst H33342 was used as nuclear loc...

Background SNF1-related protein kinases 2 (SnRK2s) are key regulators of the plant response to osmotic stress. They are transiently activated in response to drought and salinity. Based on a phylogenetic analysis SnRK2s are divided into three groups. The classification correlates with their response to abscisic acid (ABA); group 1 consists SnRK2s no...

The plant hormone abscisic acid (ABA), a key regulator in many crucial developmental and physiological processes, recruits diverse components into precisely regulated signaling network. We recently discovered that MAPKKK18, an ABA-activated kinase, is regulated by the protein phosphatase type 2C (PP2C) ABI1 and the kinase SnRK2.6, both components o...

Phosphorylation and dephosphorylation events play an important role in the transmission of the abscisic acid (ABA) signal. Although SnRK2 protein kinases and group A PP2C-type phosphatases constitute the core ABA pathway, MAPK pathways are also involved in plant response to ABA. However, still little is known about the interplay between MAP kinases...

Localization of the conserved PP2C catalytic domain in deduced BnaABI1 protein sequences. The PP2C domain family was defined and mapped in BnaABI1 protein sequences using The Conserved Domain Database of the NCBI (http:// www. ncbi. nlm. nih. gov/ Structure/ cdd/ wrpsb. cgi). The scale is shown at the top in number of amino acids

In this report we characterized the Arabidopsis ABI1 gene orthologue and Brassica napus gene paralogues encoding protein phosphatase 2C (PP2C, group A), which is known to be a negative regulator of the ABA signaling pathway. Six homologous B. napus sequences were identified and characterized as putative PP2C group A members. To gain insight into th...

Histone acetyltransferase complex NuA4 and histone variant exchanging complex SWR1 are two chromatin modifying complexes which act cooperatively in yeast and share some intriguing structural similarities. Protein subunits of NuA4 and SWR1-C are highly conserved across eukaryotes, but form different multiprotein arrangements. For example, the human...

Plant transformation and exogenous protein expression is essential for molecular biology and biotechnology. Current approaches of stable plant transformation might be problematic and very time-consuming. Because of this, transient expression in protoplasts has become valuable alternative, being less cost and time-effective at the same time. Excelle...

Ethylene plays a crucial role in various biological processes and therefore its biosynthesis is strictly regulated by multiple mechanisms. Post-translational regulation, which is pivotal in controlling ethylene biosynthesis, impacts 1-aminocyclopropane 1-carboxylate synthase (ACS) protein stability via the complex interplay of specific factors. Her...

Current findings have demonstrated that MAP kinases play an important role in the transmission of the ABA signal. The critical outstanding question is: which MAPKs are involved in the ABA signal transduction. Our project involves the identification and functional analysis of the MAPKKK18 in relation to ABA signalling. To verify the ABA responsivene...

We investigated the expression profiles and genomic organisation of the ABA-responsive genes encoding protein phosphatases 2C (PP2C, group A members) in Brassica oleracea to better understand their functional and genetic relations. Gene expression profiling of drought responsive genes in B. oleracea and Arabidopsis thaliana revealed significant dif...

Despite the studies indicating that MAP kinase cascades function in ABA signalling, little is known about the interplay between MAP kinases and protein phosphatases 2C in the regulation of ABA signalling and response. MAP kinase cascade is a conserved module comprising of at least three elements: MAPKKKs, MAPKKs, and MAPKs. A group of MAPKKKK invol...

Brassica species are particularly important vegetable crops, that have been studied in many aspects of plant biology including seed growth, development, disease resistance and abiotic stress tolerance. In the past decade new genomic resources have been developed and subsequently used for a generation of tools to enable genome–wide screens in Brassi...

We report on the characterization of the interaction between reactive oxygen species signalling and abscisic acid (ABA)-mediated gene network in ozone (O(3)) stress response. To identify the stress-related signalling pathways and possible cross-talk controlled by an ABA-negative regulator, the protein phosphatase 2C abscisic acid insensitive1 (ABI1...

For many plant species ozone stress has become much more severe in the last decade. The accumulating evidence for the significant effects of ozone pollutant on crop and forest yield situate ozone as one of the most important environmental stress factors that limits plant productivity worldwide. Today, transcriptomic approaches seem to give the best...

A major progress has been made in the last decade in the understanding of molecular mechanisms involved in plant responses to stresses. This has been achieved by application of a high-throughput genomics tools. Transcriptome analysis based on the DNA microarray technique has proved its effectiveness in studies of genome level responses to environme...

High ozone concentration generates oxidative stress in plants. To investigate the detailed transcriptional regulation of Arabidopsis thaliana genes encoding antioxidant enzymes upon ozone stress, we performed a microarray analysis using Affymetrix GeneChip technology. Our transcription profiling revealed a differential expression equal or greater t...