Geschmack ist vorhersagbar: Mit FlavorMiner. FlavorMiner heißt das Tool, das IPB-Chemiker und Partner aus Kolumbien jüngst entwickelt haben. Das Programm kann, basierend auf maschinellem Lernen (KI), anhand der…
Seit Februar 2021 bietet Wolfgang Brandt, ehemaliger Leiter der Arbeitsgruppe Computerchemie am IPB, sein Citizen Science-Projekt zur Pilzbestimmung an. Dafür hat er in regelmäßigen Abständen öffentliche Vorträge zur Vielfalt…
Niemeyer, M.; Parra, J. O. F.; Calderón Villalobos, L. I. A.;An in vitro assay to recapitulate hormone-triggered and SCF-mediated protein ubiquitylationLois, L.M., Trujillo, M.Methods Mol. Biol.258143-56(2023)ISBN:978-1-0716-2783-9DOI: 10.1007/978-1-0716-2784-6_4
Signaling proteins trigger a sequence of molecular switches in the cell, which permit development, growth, and rapid adaptation to changing environmental conditions. SCF-type E3 ubiquitin ligases recognize signaling proteins prompting changes in their fate, one of these being ubiquitylation followed by degradation by the proteasome. SCFs together with their ubiquitylation targets (substrates) often serve as phytohormone receptors, responding and/or assembling in response to fluctuating intracellular hormone concentrations. Tracing and understanding phytohormone perception and SCF-mediated ubiquitylation of proteins could provide powerful clues on the molecular mechanisms utilized for plant adaptation. Here, we describe an adaptable in vitro system that uses recombinant proteins and enables the study of hormone-triggered SCF-substrate interaction and the dynamics of protein ubiquitylation. This system can serve to predict the requirements for protein recognition and to understand how phytohormone levels have the power to control protein fate.
Publikation
Terrile, M. C.; Tebez, N. M.; Colman, S. L.; Mateos, J. L.; Morato-López, E.; Sánchez-López, N.; Izquierdo-Álvarez, A.; Marina, A.; Calderón Villalobos, L. I. A.; Estelle, M.; Martínez-Ruiz, A.; Fiol, D. F.; Casalongué, C. A.; Iglesias, M. J.;S-Nitrosation of E3 ubiquitin ligase complex components regulates hormonal signalings in ArabidopsisFront. Plant Sci.12794582(2022)DOI: 10.3389/fpls.2021.794582
E3 ubiquitin ligases mediate the last step of the ubiquitination pathway in the ubiquitin-proteasome system (UPS). By targeting transcriptional regulators for their turnover, E3s play a crucial role in every aspect of plant biology. In plants, SKP1/CULLIN1/F-BOX PROTEIN (SCF)-type E3 ubiquitin ligases are essential for the perception and signaling of several key hormones including auxins and jasmonates (JAs). F-box proteins, TRANSPORT INHIBITOR RESPONSE 1 (TIR1) and CORONATINE INSENSITIVE 1 (COI1), bind directly transcriptional repressors AUXIN/INDOLE-3-ACETIC ACID (AUX/IAA) and JASMONATE ZIM-DOMAIN (JAZ) in auxin- and JAs-depending manner, respectively, which permits the perception of the hormones and transcriptional activation of signaling pathways. Redox modification of proteins mainly by S-nitrosation of cysteines (Cys) residues via nitric oxide (NO) has emerged as a valued regulatory mechanism in physiological processes requiring its rapid and versatile integration. Previously, we demonstrated that TIR1 and Arabidopsis thaliana SKP1 (ASK1) are targets of S-nitrosation, and these NO-dependent posttranslational modifications enhance protein-protein interactions and positively regulate SCFTIR1 complex assembly and expression of auxin response genes. In this work, we confirmed S-nitrosation of Cys140 in TIR1, which was associated in planta to auxin-dependent developmental and stress-associated responses. In addition, we provide evidence on the modulation of the SCFCOI1 complex by different S-nitrosation events. We demonstrated that S-nitrosation of ASK1 Cys118 enhanced ASK1-COI1 protein-protein interaction. Overexpression of non-nitrosable ask1 mutant protein impaired the activation of JA-responsive genes mediated by SCFCOI1 illustrating the functional relevance of this redox-mediated regulation in planta. In silico analysis positions COI1 as a promising S-nitrosation target, and demonstrated that plants treated with methyl JA (MeJA) or S-nitrosocysteine (NO-Cys, S-nitrosation agent) develop shared responses at a genome-wide level. The regulation of SCF components involved in hormonal perception by S-nitrosation may represent a key strategy to determine the precise time and site-dependent activation of each hormonal signaling pathway and highlights NO as a pivotal molecular player in these scenarios.
Publikation
Orosa, B.; Üstün, S.; Calderón Villalobos, L. I. A.; Genschik, P.; Gibbs, D.; Holdsworth, M. J.; Isono, E.; Lois, M.; Trujillo, M.; Sadanandom, A.;Plant proteostasis – shaping the proteome: a research community aiming to understand molecular mechanisms that control protein abundanceNew Phytol.2271028-1033(2020)DOI: 10.1111/nph.16664
Cullin RING-type E3 ubiquitin ligases SCFTIR1/AFB1-5 and their AUX/IAA targets perceive the phytohormone auxin. The F-box protein TIR1 binds a surface-exposed degron in AUX/IAAs promoting their ubiquitylation and rapid auxin-regulated proteasomal degradation. Here, by adopting biochemical, structural proteomics and in vivo approaches we unveil how flexibility in AUX/IAAs and regions in TIR1 affect their conformational ensemble allowing surface accessibility of degrons. We resolve TIR1·auxin·IAA7 and TIR1·auxin·IAA12 complex topology, and show that flexible intrinsically disordered regions (IDRs) in the degron’s vicinity, cooperatively position AUX/IAAs on TIR1. We identify essential residues at the TIR1 N- and C-termini, which provide non-native interaction interfaces with IDRs and the folded PB1 domain of AUX/IAAs. We thereby establish a role for IDRs in modulating auxin receptor assemblies. By securing AUX/IAAs on two opposite surfaces of TIR1, IDR diversity supports locally tailored positioning for targeted ubiquitylation, and might provide conformational flexibility for a multiplicity of functional states.