Monothiol glutaredoxin-BolA interactions: redox control of Arabidopsis thaliana BolA2 and SufE1

J Couturier, HC Wu, T Dhalleine, H Pégeot, D Sudre… – Molecular Plant, 2013.

Abstract

A functional relationship between monothiol glutaredoxins and BolA has been unravelled by genomic analyses and in several high-throughput studies. Phylogenetic analyses coupled to transient expression of GFP fusions indicated that, in addition to the sulfurtransferase SufE1, which contains a C-terminal BolA domain, three BolA isoforms exist inArabidopsis thaliana, BolA1 being plastidial, BolA2 nucleo-cytoplasmic and BolA4 dual-targeted to mitochondria and plastids. Binary yeast-two hybrid experiments demonstrated that all BolAs and SufE1, via its BolA domain, can interact with all monothiol glutaredoxins. Most interactions between protein couples of the same sub-cellular compartment have been confirmed by bimolecular fluorescence complementation. In vitroexperiments indicated that monothiol glutaredoxins could regulate the redox state of BolA2 and SufE1, both proteins possessing a single conserved reactive cysteine. Indeed, a glutathionylated form of SufE1 lost its capacity to activate the cysteine desulfurase, Nfs2, but it is reactivated by plastidial glutaredoxins. Besides, a monomeric glutathionylated form and a dimeric disulfide-bridged form of BolA2 can be preferentially reduced by the nucleo-cytoplasmic GrxS17. These results indicate that the glutaredoxin-BolA interaction occurs in several sub-cellular compartments and suggest that a redox regulation mechanism, disconnected from their capacity to form iron-sulfur cluster-bridged heterodimers, may be physiologically relevant for BolA2 and SufE1.