Movement of a sub-population of the light harvesting complex (LHCII) from grana to stroma lamellae as a consequence of its phosphorylation

David J. Kyle, Ting Yun Kuang, Janet L. Watson, Charles J. Arntzen

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Abstract

Phosphorylation in vitro of the light-harvesting chlorophyll a b protein complex associated with Photosystem II (LHCII) resulted in the lateral migration of a subpopulation of LHCII from the grana to the stroma lamellae. This movement was characterized by a decrease in the chlorophyll a b ratio and an increase in the 77 K fluorescence emission at 681 nm in the stroma lamellae following phosphorylation. Polyacrylamide gel electrophoresis indicated that the principal phosphoproteins under these conditions were polypeptides of 26-27 kDa. These polypeptides increased in relative amount in the stroma lamellae and decreased in the grana during phosphorylation. Pulse/chase experiments confirmed that the polypeptides were labelled in the grana and moved to the stroma lamellae in the subsequent chase period. A fraction at the phospho-LHCII, however, was unable to move and remained associated with the grana fraction. LHCII which moved out into the stroma lamellae effectively sensitized Photosystem I (PS I), since the ability to excite fluorescence emission at 735 nm (at 77 K) by chlorophyll b was increased following phosphorylation. These data support the 'mobile antenna' hypothesis proposed by Kyle, Staehelin and Arntzen (Arch. Biochem. Biophys. (1983) 222, 527-541) which states that the alterations in the excitation-energy distribution induced by LHCII phosphorylation are, in part, due to the change in absorptive cross-section of PS II and PS I, resulting specifically from the movement of LHCII antennae chlorophylls from the PS-II-enriched grana to the PS-I-enriched stroma lamellae.

Original languageEnglish (US)
Pages (from-to)89-96
Number of pages8
JournalBBA - Bioenergetics
Volume765
Issue number2
DOIs
StatePublished - May 29 1984

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Keywords

  • (Pea thylakoid)
  • Chloroplast membrane
  • Excitation-energy distribution
  • Light-harvesting complex
  • Protein phosphorylation

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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