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<em>Arabidopsis thaliana</em> AUCSIA-1 Regulates Auxin Biology and Physically Interacts with a Kinesin-Related Protein

By Barbara Molesini (61502), Tiziana Pandolfini (3127), Youry Pii (30735), Arthur Korte (149786) and Angelo Spena (3128)


<div><p><em>Aucsia</em> is a green plant gene family encoding 44–54 amino acids long miniproteins. The sequenced genomes of most land plants contain two <em>Aucsia</em> genes. RNA interference of both tomato (<em>Solanum lycopersicum</em>) <em>Aucsia</em> genes (<em>SlAucsia</em>-1 and <em>SlAucsia</em>-2) altered auxin sensitivity, auxin transport and distribution; it caused parthenocarpic development of the fruit and other auxin-related morphological changes. Here we present data showing that the <em>Aucsia</em>-1 gene of <em>Arabidopsis thaliana</em> alters, by itself, root auxin biology and that the AtAUCSIA-1 miniprotein physically interacts with a kinesin-related protein. The <em>AtAucsia</em>-1 gene is ubiquitously expressed, although its expression is higher in roots and inflorescences in comparison to stems and leaves. Two allelic mutants for <em>AtAucsia</em>-1 gene did not display visible root morphological alterations; however both basipetal and acropetal indole-3-acetic acid (IAA) root transport was reduced as compared with wild-type plants. The transcript steady state levels of the auxin efflux transporters ATP BINDING CASSETTE subfamily B (ABCB) <em>ABCB1</em>, <em>ABCB4</em> and <em>ABCB19</em> were reduced in <em>ataucsia</em>-1 plants. In <em>ataucsia</em>-1 mutant, lateral root growth showed an altered response to i) exogenous auxin, ii) an inhibitor of polar auxin transport and iii) ethylene. Overexpression of <em>AtAucsia</em>-1 inhibited primary root growth. <em>In vitro</em> and <em>in vivo</em> protein-protein interaction experiments showed that AtAUCSIA-1 interacts with a 185 amino acids long fragment belonging to a 2712 amino acids long protein of unknown function (<em>At4g31570</em>). Bioinformatics analysis indicates that the AtAUCSIA-1 interacting protein (AtAUCSIA-1IP) clusters with a group of CENP-E kinesin-related proteins. Gene ontology predictions for the two proteins are consistent with the hypothesis that the AtAUCSIA-1/AtAUCSIA-1IP complex is involved in the regulation of the cytoskeleton dynamics underlying auxin biology.</p> </div

Topics: Cell Biology, Genetics, Molecular Biology, Biological Sciences, Developmental Biology, aucsia-1, regulates, auxin, interacts, kinesin-related
Year: 2012
DOI identifier: 10.1371/journal.pone.0041327
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Provided by: FigShare
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