English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Plastids contain a NAD(P)H-plastoquinone-oxidoreductase which is homologous to the eubacterial and mitochondrial NADH-ubiquinone-oxidoreductase (complex I), but the meta­bolic function of the enzyme is still not yet understood. The enzyme consists of at least eleven subunits (NDH-A-K), which are all encoded in the plastid chromosome. In this study we have investigated the tissue-specific and light-dependent expression of the subunits NDH-H and NDH-K in maize, rice and mustard by western blot analysis. No NDH-proteins were found in root tissue, indicating that the presence of the enzyme is confined to leaf plastids. Analysis of the expression during the light-dependent development from etioplasts to chloro­plasts showed that high amounts of NDH-H and -K are present in etioplasts. The same result was found for subunits of the ATPase. In contrast, components of the photosynthetic electron transport chain (PSII-B, cytochrome f and PSI-D) accumulated only after illumination. In an second investigation, the expression of NDH-proteins along the natural chloroplast develop­ mental gradient from proplastids to chloroplasts in light-grown maize leaves was analysed. NDH-H and NDH-K as well as the ATPase were present at the youngest stages of chloro­plast development, while the massive accumulation of subunits of the photosystems and the cytochrome b 6 /f-complex took place in older leaf sections. We conclude from these studies that a functional NAD(P)H-plastoquinone-oxidoreductase is present in etioplasts and devel­oping plastids. We suggest that the enzyme serves the generation of a proton gradient across the prothylakoid membrane that is necessary for protein integration into the membrane at developmental stages where a functional photosynthetic electron transport chain is not yet operating.

The Expression of Subunits of the Mitochondrial Complex I-Homologous NAD(P)H-Plastoquinone-Oxidoreductase during Plastid Development