Changes in the OXPHOS system in leaf and root mitochondria of Arabidopsis thaliana subjected to long-term sulphur deficiency

Monika Ostaszewska-Bugajska,Izabela M Juszczuk

doi:10.1007/s11738-016-2155-1

Monika Ostaszewska-Bugajska, Izabela M Juszczuk

Open Access

https://doi.org/10.1007/s11738-016-2155-1

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Journal: Acta Physiologiae Plantarum	Publication Date: May 14, 2016
Citations: 3	License type: CC BY 4.0

Affiliation: University of Warsaw

Abstract

Long-term sulphur (S) deficiency in Arabidopsis thaliana affects the functioning of the mitochondrial oxidative phosphorylation system (OXPHOS) via alteration of the multisubunit NADH-ubiquinone oxidoreductase (Complex I; EC 1.6.5.3), which contains several iron–sulphur clusters. Densitometric analysis of bands of respiratory chain complexes after one-dimensional blue-native polyacrylamide gel electrophoresis (BN-PAGE) showed that levels and in-gel capacities of Complex I in leaf and root mitochondria were lower than those of the control. Two-dimensional BN/SDS-PAGE showed lower abundance of all Complex I subunits, but the qualitative structural composition (subunit expression and mobility) did not change. In mitochondria of S-deficient A. thaliana, impairment of Complex I could be compensated to some extent by additional type II NADH dehydrogenases that do not contain iron–sulphur clusters. The level and capacity of external NADH dehydrogenases in leaf and root mitochondria was higher under S deficiency, but that of internal NADH dehydrogenases did not differ from the control. The amount of COXII (mitochondrial-encoded subunit of cytochrome c oxidase in Complex IV; EC 1.9.3.1) and the capacity of Complex IV were lower under S deficiency, but levels of alternative oxidase, a bypass to Complex IV, did not change. We discuss S deficiency in A. thaliana in relation to the assembly and stability of Complex I and to a bypass of Complex I by external type II NADH dehydrogenases.

Highlights

The oxidative phosphorylation system (OXPHOS) in mitochondria consists of five multi-subunit protein complexes (I–V)
The level and capacity of external NADH dehydrogenases in leaf and root mitochondria was higher under S deficiency, but that of internal NADH dehydrogenases did not differ from the control
To analyse the profile of OXPHOS complexes, mitochondria were isolated from the leaves or roots of A. thaliana plants that exhibited symptoms of S deficiency; in addition to morphological changes (Fig. 1), expression of the low sulphur 1 gene (LSU1) and low sulphur 3 gene (LSU3) genes was increased by 150 and 85 %, respectively (Fig. 7)

Summary

Introduction

The oxidative phosphorylation system (OXPHOS) in mitochondria consists of five multi-subunit protein complexes (I–V). Four of them (Complexes I–IV) are oxidoreductases that form the respiratory chain. The backflow of protons into the matrix mediates phosphorylation of ADP to ATP by Complex V (F0F1 ATP synthase; EC 3.6.1.3). A special feature of plant mitochondria is the presence of additional oxidoreductases, internal and external type II NAD(P)H dehydrogenases (NDin/exNADH) and an alternative oxidase (AOX) in the OXPHOS system (Rasmusson et al 2008; Vanlerberghe 2013). The input site for electrons derived from the oxidation of NADH could be either Complex I or NDin/exNADH, and oxygen can be reduced to water by either COX or AOX at the end of the respiratory chain (Rasmusson et al 2008)

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