Impact on Arabidopsis growth and stress resistance of depleting the Maf1 repressor of RNA polymerase III.

Joseph Blayney,Joseph Violet,Katherine J Denby,Liam Barratt,James Geary,Robert J White,Katherine Paine,Ruby Chrisp,Ian A Graham,Laçin Tavukçu,Fabián E Vaistij

doi:10.1016/j.gene.2021.146130

Abstract

Maf1 is a transcription factor that is conserved in sequence and structure between yeasts, animals and plants. Its principal molecular function is also well conserved, being to bind and repress RNA polymerase (pol) III, thereby inhibiting synthesis of tRNAs and other noncoding RNAs. Restrictions on tRNA production and hence protein synthesis can provide a mechanism to preserve resources under conditions that are suboptimal for growth. Accordingly, Maf1 is found in some organisms to influence growth and/or stress survival. Because of their sessile nature, plants are especially vulnerable to environmental changes and molecular adaptations that enhance growth under benign circumstances can increase sensitivity to external challenges. We tested if Maf1 depletion in the model plant Arabidopsis affects growth, pathogen resistance and tolerance of drought or soil salinity, a common physiological challenge that imposes both osmotic and ionic stress. We find that disruption of the Maf1 gene or RNAi-mediated depletion of its transcript is well-tolerated and confers a modest growth advantage without compromising resistance to common biotic and abiotic challenges.

Highlights

Maf1 is a highly-conserved transcription factor found in yeasts, animals and plants (Ciesla and Boguta, 2008; Graczyk et al, 2018), with 36% amino acid identity between the human and Arabidopsis proteins
As growth restraint can provide protection against stress, we considered the possibility that plants relieved of Maf1 might be more vulnerable to environmental challenges, even if they thrive under optimal conditions
Our data support previous studies demonstrating that transcription by pol III in plants is restrained by Maf1, a regulator that is wellconserved through evolution (Ahn et al, 2019; Soprano et al, 2018; Soprano et al, 2013; Soprano et al, 2017)

Summary

Introduction

Maf is a highly-conserved transcription factor found in yeasts, animals and plants (Ciesla and Boguta, 2008; Graczyk et al, 2018), with 36% amino acid identity between the human and Arabidopsis proteins. Further genetic analyses established that S. cerevisiae Maf represses pol IIImediated transcription when yeast encounter adverse growth conditions, such as nutrient deprivation (Boguta, 2013; Upadhya et al, 2002) This may be important for metabolic economy, as pol III synthesizes highly abundant transcripts that account for ∼20% of total RNA content (Willis, 2018).

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Conclusion