The Chloroplast NAD(P)H Dehydrogenase Complex Interacts with Photosystem I in Arabidopsis

Lianwei Peng,Hideyuki Shimizu,Toshiharu Shikanai

doi:10.1074/jbc.m803207200

Lianwei Peng, Hideyuki Shimizu + Show 1 more

Open Access

https://doi.org/10.1074/jbc.m803207200

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Abstract

The chloroplast NAD(P)H dehydrogenase (NDH) complex is involved in photosystem I (PSI) cyclic and chlororespiratory electron transport in higher plants. Although biochemical and genetic evidence for its subunit composition has accumulated, it is not enough to explain the complexes putative activity of NAD(P)H-dependent plastoquinone reduction. We analyzed the NDH complex by using blue native PAGE and found that it interacts with PSI to form a novel supercomplex. Mutants lacking NdhL and NdhM accumulated a pigment-protein complex with a slightly lower molecular mass than that of the NDH-PSI supercomplex; this may be an intermediate supercomplex including PSI. This intermediate is unstable in mutants lacking NdhB, NdhD, or NdhF, implying that it includes some NDH subunits. Analysis of thylakoid membrane complexes using sucrose density gradient centrifugation supported the presence of the NDH-PSI supercomplex in vivo. Although the NDH complex exists as a monomer in etioplasts, it interacts with PSI to form a supercomplex within 48 h during chloroplast development.

Highlights

Generally accepted that chloroplast NAD(P)H dehydrogenase (NDH) is more closely related to the cyanobacterial NDH-1 complex than to the mitochondrial complex I in the same species [3, 6]
These results indicate that the high molecular mass forms of the NDH complex may be universally present in plant chloroplasts
In addition to the major spot corresponding to the photosystem I (PSI) monomer, a trace amount of PSI occurred in a putative supercomplex at the high molecular mass position, co-localized with NDH subunits in the blue native (BN) gel

Summary

Introduction

Generally accepted that chloroplast NDH is more closely related to the cyanobacterial NDH-1 complex than to the mitochondrial complex I in the same species [3, 6]. These results indicate that the high molecular mass forms of the NDH complex may be universally present in plant chloroplasts. These results indicate that NDH and PSI co-localize in the BN gel, forming Band I, which does not contain PSII or the cytochrome b6f complex.

Results

Conclusion