The Lhca antenna complexes of higher plants photosystem I

Roberta Croce, Tomas Morosinotto, Simona Castelletti, Jacques Breton, Roberto Bassi*

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

The Lhca antenna complexes of photosystem I (PSI) have been characterized by comparison of native and recombinant preparations. Eight Lhca polypeptides have been found to be all organized as dimers in the PSI-LHCI complex. The red emission fluorescence is associated not only with Lhca1-4 heterodimer, but also with dimers containing Lhca2 and/or Lhca3 complexes. Reconstitution of Lhca1 and Lhca4 monomers as well as of the Lhca1-4 dimer in vitro was obtained. The biochemical and spectroscopic features of these three complexes are reported. The monomers Lhca1 and Lhca4 bind 10 Chls each, while the Chl a/b ratio is lower in Lhca4 as compared to Lhca1. Three carotenoid binding sites have been found in Lhca1, while only two are present in Lhca4. Both complexes contain lutein and violaxanthin while β-carotene is selectively bound to the Lhca1-4 dimer in substoichiometric amounts upon dimerization. Spectral analysis revealed the presence of low energy absorption forms in Lhca1 previously thought to be exclusively associated with Lhca4. It is shown that the process of dimerization changes the spectroscopic properties of some chromophores and increases the amplitude of the red absorption tail of the complexes. The origin of these spectroscopic features is discussed.

Original languageEnglish
Pages (from-to)29-40
Number of pages12
JournalBiochimica et Biophysica Acta (BBA) - Bioenergetics
Volume1556
Issue number1
DOIs
Publication statusPublished - 3 Oct 2002

Keywords

  • Chlorophyll-protein
  • Photosynthesis
  • Recombinant Lhc protein

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