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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Plant Sci. | doi: 10.3389/fpls.2019.01469

The MATH-BTB Protein TaMAB2 Accumulates in Ubiquitin-containing Foci and Interacts with the Translation Initiation Machinery in Arabidopsis

  • 1Division of Molecular Biology, Department of Biology, University of Zagreb, Croatia
  • 2Genos Glycoscience Research Laboratory, Croatia
  • 3Agriculture & Food, Commonwealth Scientific and Industrial Research Organisation, Australia
  • 4Division of Biochemistry, Department of Chemistry, Faculty of Science, University of Zagreb, Croatia
  • 5Department of Cell Biology and Plant Biochemistry, Faculty of Biology and Preclinical Medicine, University of Regensburg, Germany

MATH-BTB proteins are known to act as substrate-specific adaptors of CUL3-based E3 ligases in the ubiquitin proteasome pathway. Their BTB domain binds to CUL3 scaffold proteins and the less conserved MATH domain targets a highly diverse collection of substrate proteins to promote their ubiquitination and subsequent degradation. In plants, a significant expansion of the MATH-BTB family occurred in the grasses. Here, we report analysis of TaMAB2, a MATH-BTB protein transiently expressed at the onset of embryogenesis in wheat. Due to difficulties in studying its role in zygotes and early embryos, we have overexpressed TaMAB2 in Arabidopsis to generate gain-of-function mutants and to elucidate interaction partners and substrates. Overexpression plants showed severe growth defects as well as disorganization of microtubule bundles indicating that TaMAB2 interacts with substrates in Arabidopsis. In tobacco BY-2 cells, TaMAB2 showed a microtubule and ubiquitin-associated cytoplasmic localization pattern in form of foci. Its direct interaction with CUL3 suggests functions in targeting specific substrates for ubiquitin-dependent degradation. Although direct interactions with tubulin could not be confimed, tandem affinity purification of TaMAB2 interactors point towards cytoskeletal proteins including tubulin and actin as well as the translation initiation machinery. The idenification of various subunits of eucaryotic translation initiation factors eIF3 and eIF4 as TaMAB2 interactors indicate regulation of translation initiation as a major function during onset of embryogenesis in plants.

Keywords: Triticum aestivum, proteasomal degradation, actin11, Cytoskeleton, eIF4, eIF3, translation initiation, MATH-BTB

Received: 24 Jun 2019; Accepted: 22 Oct 2019.

Copyright: © 2019 Bauer, Škiljaica, Malenica, Razdorov, Klasić, Juranić, Močibob, Sprunck, Dresselhaus and Leljak-Levanić. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Dunja Leljak-Levanić, Division of Molecular Biology, Department of Biology, University of Zagreb, Zagreb, Croatia, dunja@zg.biol.pmf.hr