C-terminal Redox Domain of Arabidopsis APR1 is a Non-Canonical Thioredoxin Domain with Glutaredoxin Function.

Chen Chen,Chien Chien,Cho Cho,Chang Chang,Hsu Hsu

doi:10.3390/antiox8100461

Chen Chen, Chien Chien + Show 3 more

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https://doi.org/10.3390/antiox8100461

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Journal: Antioxidants	Publication Date: Oct 8, 2019
Citations: 4	License type: CC BY 4.0

Affiliation: National Taiwan University, Academia Sinica

Abstract

Sulfur is an essential nutrient that can be converted into utilizable metabolic forms to produce sulfur-containing metabolites in plant. Adenosine 5′-phosphosulfate (APS) reductase (APR) plays a vital role in catalyzing the reduction of activated sulfate to sulfite, which requires glutathione. Previous studies have shown that the C-terminal domain of APR acts as a glutathione-dependent reductase. The crystal structure of the C-terminal redox domain of Arabidopsis APR1 (AtAPR1) shows a conserved α/β thioredoxin fold, but not a glutaredoxin fold. Further biochemical studies of the redox domain from AtAPR1 provided evidence to support the structural observation. Collectively, our results provide structural and biochemical information to explain how the thioredoxin fold exerts the glutaredoxin function in APR.

Highlights

Sulfur, which is a crucial element in life, can be incorporated into the amino acids cysteine and methionine, iron-sulfur clusters, and other cofactors [1,2]
The GST-tag was excised from the Arabidopsis thaliana APR1 (AtAPR1) redox domain with thrombin protease, which resulted in a Gly-Ser-Pro-Glu-Phe-Met extra sequence at the N-terminus
The molecular mass of the AtAPR1 redox domain in solution determined by size-exclusion chromatography was about 13 kDa (Figure 1B), which indicates the monomeric form of the AtAPR1 redox domain

Summary

Introduction

Sulfur, which is a crucial element in life, can be incorporated into the amino acids cysteine and methionine, iron-sulfur clusters, and other cofactors [1,2]. A variety of S-containing secondary metabolites are produced, which usually play a significant role in defense against pathogens and herbivores in plant [3,4]. For incorporation into bioorganic compounds, oxidized inorganic sulfur compounds (usually sulfate) need to be reduced in the pathway of assimilatory sulfate reduction. Sulfate is first activated by adenosine triphosphate (ATP) sulfurylase, forming. 5 -adenylylsulfate (APS), which alternatively can be phosphorylated by APS kinase and forms. It was accepted that plants, algae, and phototrophic bacteria use APS for assimilatory sulfate reduction, whereas bacteria and fungi use PAPS. A two-step catalytic process was first demonstrated in Arabidopsis, in a prokaryotic organism, Mycobacteria tuberculosis. The first step is the reaction between the key enzyme APS reductase (APR)

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