The dual targeting ability of type II NAD(P)H dehydrogenases arose early in land plant evolution

Lin Xu,Simon R Law,Monika W Murcha,Chris Carrie,James Whelan

doi:10.1186/1471-2229-13-100

Abstract

BackgroundType II NAD(PH) dehydrogenases are located on the inner mitochondrial membrane of plants, fungi, protists and some primitive animals. However, recent observations have been made which identify several Arabidopsis type II dehydrogenases as dual targeted proteins. Targeting either mitochondria and peroxisomes or mitochondria and chloroplasts.ResultsMembers of the ND protein family were identified in various plant species. Phylogenetic analyses and subcellular targeting predictions were carried out for all proteins. All ND proteins from three model plant species Arabidopsis, rice and Physcomitrella were cloned as N- and C-terminal GFP fusions and subcellular localisations were determined. Dual targeting of plant type II dehydrogenases was observed to have evolved early in plant evolution and to be widespread throughout different plant species. In all three species tested dual targeting to both mitochondria and peroxisomes was found for at least one NDA and NDB type protein. In addition two NDB type proteins from Physcomitrella were also found to target chloroplasts. The dual targeting of NDC type proteins was found to have evolved later in plant evolution.ConclusionsThe functions of type II dehydrogenases within plant cells will have to be re-evaluated in light of this newly identified subcellular targeting information.

Highlights

Type II NAD(PH) dehydrogenases are located on the inner mitochondrial membrane of plants, fungi, protists and some primitive animals
Phylogenetic analyses and subcellular targeting predictions Previously, we had determined that a number of NAD(P)H dehydrogenases (ND) proteins from Arabidopsis thaliana are dual targeted to several locations including: mitochondria and peroxisomes or mitochondria and plastids [25]
GFP tagging of PpNDC1 in Physcomitrella tissue resulted in only plastid targeting (Figure 7). These results suggest that in lower plants such as Physcomitrella, NDC1 proteins are only targeted to plastids, and in higher plants such as Arabidopsis and rice NDC1 has acquired targeting to mitochondria during plant evolution

Summary

Introduction

Type II NAD(PH) dehydrogenases are located on the inner mitochondrial membrane of plants, fungi, protists and some primitive animals. Recent observations have been made which identify several Arabidopsis type II dehydrogenases as dual targeted proteins. Type II ND proteins were first identified in potato [18] and have been identified in fungi, protists, some bacteria and some primitive animals [19]. The function of these type II ND proteins is that when they are linked to an alternative oxidase (AOX) they constitute a non-phosphorylating respiratory pathway that enables the redox status of the cell to evade adenylate control [20]. Specific studies altering the expression or inactivating the expression of specific type II ND proteins suggest roles in the capacity of NAD(P)H oxidation (nda1) [21]; reactive oxygen species formation and altered phenotypes (ndb4) [19]

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