ANGUSTIFOLIA, a Plant Homolog of CtBP/BARS Localizes to Stress Granules and Regulates Their Formation.

Hemal Bhasin,Martin Hülskamp

doi:10.3389/fpls.2017.01004

Abstract

The ANGUSTIFOLIA (AN) gene in Arabidopsis is important for a plethora of morphological phenotypes. Recently, AN was also reported to be involved in responses to biotic and abiotic stresses. It encodes a homolog of the animal C-terminal binding proteins (CtBPs). In contrast to animal CtBPs, AN does not appear to function as a transcriptional co-repressor and instead functions outside nucleus where it might be involved in Golgi-associated membrane trafficking. In this study, we report a novel and unexplored role of AN as a component of stress granules (SGs). Interaction studies identified several RNA binding proteins that are associated with AN. AN co-localizes with several messenger ribonucleoprotein granule markers to SGs in a stress dependent manner. an mutants exhibit an altered SG formation. We provide evidence that the NAD(H) binding domain of AN is relevant in this context as proteins carrying mutations in this domain localize to a much higher degree to SGs and strongly reduce AN dimerization and its interaction with one interactor but not the others. Finally, we show that AN is a negative regulator of salt and osmotic stress responses in Arabidopsis suggesting a functional relevance in SGs.

Highlights

Overall plant growth and development is based on the regulation of cell shape and cell division/expansion
We noted that 12 co-purified proteins are predicted to be associated with RNA metabolism suggesting that AN might be involved in the regulation of the RNA metabolism (Table 1)
A Prot-A tagged protein is co-transfected with Renilla reniformis luciferase in HEK cells and the amount of the interacting protein is determined after co-immunoprecipitation by a quantitative analysis of the luminescence (Barrios-Rodiles et al, 2005)

Summary

Introduction

Overall plant growth and development is based on the regulation of cell shape and cell division/expansion. Cell growth is tightly controlled by cell metabolism and by the availability of nutrients, cellular energy, and stress (Yuan et al, 2013). Mutations in AN lead to a plethora of growth phenotypes along with altered responses to stress and pathogen attack. Morphological phenotypes include narrow leaves, under-branched trichomes, spiral growth of roots, ovules, and siliques (Redei, 1962; Hulskamp et al, 1994; Tsukaya et al, 1994; Tsuge et al, 1996; Fulton et al, 2009; Bai et al, 2013). The narrow leaf phenotype is caused by a change in growth directionality of leaf cells and by a decreased number of cells in the width direction (Kim et al, 2002; Bai et al, 2010). It was reported that an mutants can cope better with drought stress and are more resistant to bacterial infection (Gachomo et al, 2013)

Methods

Results

Conclusion