Changes in the LHCI aggregation state during iron repletion in the unicellular red alga Rhodella violacea

Edited by Richard Cogdell

Received 28 October 2002; received in revised form 12 November 2002; accepted 18 November 2002.

Abstract

Red algae are well suited to study the effects of iron deficiency on light-harvesting complex for photosystem I (LHCI), since they are totally devoid of light-harvesting complex for photosystem II (LHCII). Iron starvation results in a reduction of the pigment content, an increase of the fluorescence yield and a new emission band at 705 nm in the 77 K fluorescence emission spectra. These changes reflect the accumulation of uncoupled, aggregated LHCI in iron-depleted cells. Reconnection of LHCI to de novo synthesized reaction center I (RCI) is the first event, which takes place after iron addition. The changes in the aggregation state of LHCI are likely to occur also in brown and green algae.

Keywords: Fluorescence, Iron deficiency, Light-harvesting complex, Iron repletion, Photosystem I assembly, Rhodella violacea

Abbreviations: β-car, β-carotene, Chl, chlorophyll, LHCI and LHCII, light-harvesting complexes for photosystems I and II, P700, photosystem I activity, PBS, phycobilisome, PSI and PSII, photosystems I and II, RCI, reaction center I, Zea, zeaxanthine

Organismes Photosynthétiques et Environnement, UMR 8543 CNRS, Département de Biologie, ENS 46 rue d’Ulm, 75230 Paris cedex 05, France

Corresponding author. Fax: (33)-1 44 32 39 35

1 Present address: Universität zu Köln, Botanisches Institut, Lehrstuhl I, Gyrhofstr. 15, D-50931 Köln, Germany.

2 Present address: Plasticité et Expression des Génomes Microbiens, Université Joseph Fourier, CNRS-FRE 2383, BP 53, 38041 Grenoble cedex 09, France.

3 Present address: Robert Hill Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK.

PII: S0014-5793(02)03748-1

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