A Look within LHCII: Differential Analysis of the Lhcb1-3 Complexes Building the Major Trimeric Antenna Complex of Higher-Plant Photosynthesis

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• 作者：Stefano Caffarri ; Roberta Croce ; Luigi Cattivelli ; and Roberto Bassi
• 刊名：Biochemistry
• 出版年：2004
• 出版时间：July 27, 2004
• 年：2004
• 卷：43
• 期：29
• 页码：9467 - 9476
• 全文大小：345K
• 年卷期：v.43,no.29(July 27, 2004)
• ISSN：1520-4995

文摘

The major antenna complex of higher-plant photosynthesis, LHCII, is composed by the productsof three genes, namely, Lhcb1-2-3. In this paper, the biochemical and spectroscopic properties of each ofthe three gene products were investigated. The three complexes were obtained by overexpression of theapoproteins in bacteria and refolding in vitro with purified pigments, thus allowing detection of differencesin the structure/function of the pigment-binding gene products. The analyses showed that Lhcb1 andLhcb2 complexes have similar pigment binding properties, although not identical, while Lhcb3 is clearlydifferent with respect to both pigment binding and spectral properties and cannot produce homotrimers invitro. Heterotrimers containing Lhcb3 together with Lhcb1 and/or -2 proteins were obtained upon assemblywith Lhcb proteins purified from thylakoids. The major functional characteristics of Lhcb3 with respectto Lhcb1 and -2 consisted in (i) a red-shift of one specific chlorophyll a chromophore, strongly affectingthe red-most region of the absorption spectrum and (ii) a different specificity for xanthophylls binding tosites L2 and N1. These properties make Lhcb3 a relative sink for excitation energy in isolated heterotrimerswith Lhcb1 + Lhcb2, and potentially, a preferential site of regulation of the antenna function in excesslight conditions.