Structural Biology & Cell Biology & Genetics

Plants are nature’s other successful experiment with multicellular life. We are interested in signaling and metabolic pathways that allow plants to grow and to develop. Our approach combines structural biology and biochemistry with cell biology and genetics in Arabidopsis.

Currently, we study how plant cells communicate with each other at their cell membrane, where they have evolved unique membrane receptor kinases. These receptors sense steroid and peptide hormones to orchestrate growth and development, to establish and maintain stem cell populations and to form plant organs and tissues. We have shown that these receptors require helper proteins for activation. We now want to obtain a molecular understanding of plant peptide hormone signaling and identify novel receptor complexes.

A second line of research is to understand how plants sense and store phosphate, an essential plant nutrient. We became interested in this topic by identifying a protein complex, which uses cytosolic ATP to generate long chains of inorganic polyphosphate, an important phosphate store in yeast. We have initiated a set of projects to test whether plants also make use of polyphosphates to store phosphate.

• A two-way molecular dialogue between embryo and endosperm is required for seed development
  Doll, N. M.; Royek, S.; Fujita, S.; Okuda, S.; Chamot, S.; Stintzi, A; Widiez, T; Hothorn, M; Schaller, A; Geldner, N; Ingram, G
• Molecular mechanism for the recognition of sequence-divergent CIF peptides by the plant receptor kinases GSO1/SGN3 and GSO2
  Okuda, Satohiro; Fujita, Satoshi; Moretti, Andrea; Hohmann, Ulrich; Doblas, Veronica G.; Ma, Y; Pfister, A; Brandt, B; Geldner, N; Hothorn, M
  Proceedings Of The National Academy Of Sciences Of The United States Of America, 10.1073/pnas.1911553117, FEB 4 2020
• A genetically validated approach for detecting inorganic polyphosphates in plants
  Zhu, Jinsheng; Loubery, Sylvain; Broger, Larissa; Zhang, Youjun; Lorenzo-Orts, Laura; et al.
  Plant Journal, 10.1111/tpj.14642, JAN 2020
• Identity and functions of inorganic and inositol polyphosphates in plants
  Lorenzo-Orts, L; Couto, D; Hothorn, M
  NEW PHYTOLOGIST, 10.1111/nph.16129 
• Plant photoreceptors and their signaling components compete for COP1 binding via VP peptide motifs
  Lau, K; Podolec, R; Chappuis, R; Ulm, R; Hothorn, M
  EMBO JOURNAL, 38 (18):10.15252/embj.2019102140 SEP 16 2019
• Two bifunctional inositol pyrophosphate kinases/phosphatases control plant phosphate homeostasis
  Zhu, J; Lau, K; Puschmann, R; Harmel, RK; Zhang, YJ; Pries, V; Gaugler, P; Broger, L; Dutta, AK; Jessen, HJ; Schaaf, G; Fernie, AR; Hothorn, LA; Fiedler, D; Hothorn, M
  ELIFE, 8 10.7554/eLife.43582 AUG 22 2019
• Plant photoreceptors and their signaling components compete for COP1 binding via VP peptide motifs
  Lau, K; Podolec, R; Chappuis, R; Ulm, R; Hothorn, M
  EMBO JOURNAL, 10.15252/embj.2019102140 
• Crystal structure of the leucine-rich repeat ectodomain of the plant immune receptor kinase SOBIR1
  Hohmann, U; Hothorn, M
  ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY, 75 488-497; 10.1107/S2059798319005291 5 MAY 2019
• Crystal structure of the pseudoenzyme PDX1.2 in complex with its cognate enzyme PDX1.3: a total eclipse
  Robinson, GC; Kaufmann, M; Roux, C; Martinez-Font, J; Hothorn, M; Thore, S; Fitzpatrick, TB
  ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY, 75 400-415; 10.1107/S2059798319002912 4 APR 2019
• Concerted expression of a cell cycle regulator and a metabolic enzyme from a bicistronic transcript in plants
  Lorenzo-Orts, L; Witthoeft, J; Deforges, J; Martinez, J; Loubery, S; Placzek, A; Poirier, Y; Hothorn, LA; Jaillais, Y; Hothorn, M
  NATURE PLANTS, 5 (2):184-+; 10.1038/s41477-019-0358-3 FEB 2019
• MacroH2A histone variants limit chromatin plasticity through two distinct mechanisms
  Kozlowski, M; Corujo, D; Hothorn, M; Guberovic, I; Mandemaker, IK; Blessing, C; Sporn, J; Gutierrez-Triana, A; Smith, R; Portmann, T; Treier, M; Scheffzek, K; Huet, S; Timinszky, G; Buschbeck, M; Ladurner, AG
  EMBO REPORTS, 19 (10):10.15252/embr.201744445 OCT 2018
• CLERK is a novel receptor kinase required for sensing of root-active CLE peptides in Arabidopsis
  Anne, Pauline; Amiguet-Vercher, Amelia; Brandt, Benjamin; Kalmbach, Lothar; Geldner, Niko; Hothorn, Michael; Hardtke, Christian S
  DEVELOPMENT   Volume: 145   Issue: 10     Article Number: UNSP dev162354  https://doi.org/10.1242/dev.162354 MAY 2018
• The SERK3 elongated allele defines a role for BIR ectodomains in brassinosteroid signalling
  Ulrich Hohmann, Joël Nicolet, Andrea Moretti, Ludwig A. Hothorn & Michael Hothorn
  Nature Plants (2018),  https://doi.org/10.1038/s41477-018-0150-9
• Mechanistic basis for the activation of plant membrane receptor kinases by SERK-family coreceptors
  Hohmann, U; Santiago, J; Nicolet, J; Olsson, V; Spiga, FM; Hothorn, LA; Butenko, MA; Hothorn, M
  PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 115 (13):3488-3493; https://doi.org/10.1073/pnas.1714972115 MAR 27 2018

• Plant membrane signaling
• Receptor kinases
• Brassinosteroid signaling
• Cytokinin signaling
• Polyphosphate metabolism
• Phosphate sensing

• Receptor agonist/antagonist development
• Structural Biology / Protein Crystallography of signaling proteins and metabolic enzymes
• Quantitative biochemistry. Protein-Protein interactions. Protein-Ligand interactions