Structure and Function of Light‐harvesting Complexes and Their Polypeptides

Zuber, Herbert

doi:10.1111/j.1751-1097.1985.tb01655.x

Cited by 177 publications

(81 citation statements)

References 185 publications

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“…All light-harvesting complexes display a remarkable similarity in the way they are constructed (Zuber, 1985;Zuber & Brunisholz, 1991). The basic structural unit is a heterodimer of small a-and 0-apoproteins containing noncovalently bound pigments (bacteriochlorophyll [BChl] and carotenoids).…”

mentioning

confidence: 99%

Predicting the structure of the light-harvesting complex II ofrhodospirillum molischianum

Hamer

et al. 1995

Protein Sci.

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We attempted to predict through computer modeling the structure of the light-harvesting complex II (LH-Ii) of Rhodospirillum molischianum, before the impending publication of the structure of a homologous protein solved by means of X-ray diffraction. The protein studied is an integral membrane protein of 16 independent polypeptides, 8 a-apoproteins and 8 @-apoproteins, which aggregate and bind to 24 bacteriochlorophyll-a's and 12 lycopenes. Available diffraction data of a crystal of the protein, which could not be phased due to a lack of heavy metal derivatives, served to test the predicted structure, guiding the search. In order to determine the secondary structure, hydropathy analysis was performed to identify the putative transmembrane segments and multiple sequence alignment propensity analyses were used to pinpoint the exact sites of the 20-residue-long transmembrane segment and the 4-residue-long terminal sequence at both ends, which were independently verified and improved by homology modeling. A consensus assignment for the secondary structure was derived from a combination of all the prediction methods used. Three-dimensional structures for the cy-and the @-apoprotein were built by comparative modeling. The resulting tertiary structures are combined, using X-PLOR, into an a@ dimer pair with bacteriochlorophyll-a's attached under constraints provided by site-directed mutagenesis and spectral data. The a@ dimer pairs were then aggregated into a quaternary structure through further molecular dynamics simulations and energy minimization. The structure of LH-I1 so determined is an octamer of a@ heterodimers forming a ring with a diameter of 70 A.

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confidence: 99%

Predicting the structure of the light-harvesting complex II ofrhodospirillum molischianum

Hamer

et al. 1995

Protein Sci.

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“…The LHCPs of PSII (LHCP-II) make up >50% of the chlorophyll-containing polypeptides ofthylakoid membranes isolated from chloroplasts (1). They have been shown to be encoded by multigene families in pea, petunia, barley, duckweed, wheat, and tomato (2)(3)(4)(5)(6).…”

mentioning

confidence: 99%

Differential expression of six light-harvesting chlorophyll a/b binding protein genes in maize leaf cell types.

Sheen¹,

Bogorad²

1986

Proc. Natl. Acad. Sci. U.S.A.

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Bundle sheath chloroplasts of maize leaves contain about one-fourth as much light-harvesting chlorophyll a/b binding protein of photosystem II (LHCP-ll) as do mesophyll chloroplasts. We have determined that this difference is, in part, the result of differential expression of different LHCP-ll genes. We have prepared and partially characterized cDNA clones specific for six LHCP-ll genes of maize. Transcripts of these six LHCP-ll genes are present at vastly different levels and account for about 95% of total LHCP-ll mRNAs in bundle sheath and mesophyll cells of illuminated dark-grown maize leaves. Three genes are preferentially expressed in mesophyll cells, and their mRNAs constitute about 54% of the total LHCP-ll transcripts in greening (24 hr) maize leaves. Two genes are expressed equally in bundle sheath and mesophyll cells. Most interestingly, the RNA of one gene that contributes about 8% of the total LHCP-II transcripts in leaves greening for 24 hr is present at a much higher level in bundle sheath than in mesophyll cells. Moreover, immunoblot analysis of maize thylakoids reveals at least five sizes of LHCP-II; these also differ from one another in their relative abundance in bundle sheath and mesophyll cells of developing maize leaves.The light-harvesting chlorophyll a/b binding proteins (LHCPs) are the major components of the antennae complexes that capture and transfer light energy to the reaction centers of photosystem I (PSI) and photosystem II (PSII). The LHCPs of PSII (LHCP-II) make up >50% of the chlorophyll-containing polypeptides ofthylakoid membranes isolated from chloroplasts (1). They have been shown to be encoded by multigene families in pea, petunia, barley, duckweed, wheat, and tomato (2-6). Furthermore, light has been demonstrated to regulate LHCP-II gene expression in plant leaves (7)(8)(9)(10)(11)(12)(13)(14). Moreover, in maize, the accumulation of LHCP-II mRNA is coordinated with carotenoid synthesis and plastid development (15,16).Maize is a C4 plant; its leaves contain two distinct photosynthetic cell types, bundle sheath cells and mesophyll cells (BSC and MC). Agranal chloroplasts in BSC are poor in PSII in relation to their activity in PSI (17, 18) and contain less LHCP-II and other PSII polypeptides (19)(20)(21)(22) than are present in the granal chloroplasts of MC. In addition, transcripts of the LHCP-II gene have been reported to be rare or absent in BSC (21, 22). However, relatively little is known concerning the number of different LHCP-II polypeptides and genes in maize or whether differences in the abundance of LHCP-II in MC and BSC is the result of quantitatively different expression of the same gene or genes or whether different LHCP genes are expressed in the two cell types.We have identified six members of the LHCP-II gene family that are actively expressed in maize leaves. To investigate the cell-type-specific expression of each of these six LHCP-II genes in developing maize leaves, shortened cDNA clones that show no cross-hybridization to each other have been use...

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“…rubrum and Rps. viridis) of bacteria, and typically has one absorption band between 820 and 860 nm, and another around 800 nm [Zub85]. For Rs.…”

Section: Light Harvesting Complexmentioning

confidence: 99%

“…All light-harvesting complexes display a remarkable similarity in the way they are constructed [Zub85,ZB91]. The basic structural unit is a heterodimer of two small polypeptides, commonly referred to as α and β, both shorter than 60 amino acids, which non-covalently bind BChla and carotenoid molecules.…”

Section: Light Harvesting Complexmentioning

confidence: 99%

Knowledge based structure prediction of the light-harvesting complex II of rhodospirillum molischianum

Hamer

et al. 1995

Global Minimization of Nonconvex Energy Functions: Molecular Conformation and Protein F

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Abstract. We illustrate in this article how one proceeds to predict the structure of integral membrane proteins using a combined approach in which molecular dynamics simulations and energy minimization are performed based on structural information from conventional structure prediction methods and experimental constraints derived from biochemical and spectroscopical data. We focus here on the prediction of the structure of the light-harvesting complex II (LH-II) of Rhodospirillum molischianum, an integral membrane protein of 16 polypeptides aggregating and binding to 24 bacteriochlorophyll a's and 12 lycopenes. Hydropathy analysis was performed to identify the putative transmembrane segments. Multiple sequence alignment propensity analyses further pinpointed the exact sites of the 20 residue long transmembrane segment and the four residue long terminal sequence at both ends, which were independently verified and improved by homology modeling. A consensus assignment for secondary structure was derived from a combination of all the prediction methods used. The three-dimensional structures for the α-and the β-apoprotein were built by comparative modeling. The resulting tertiary structures were combined into an αβ dimer pair with bacteriochlorophyll a's attached under constraints provided by site directed mutagenesis and FT Resonance Raman spectra, as well as by conservation of residues. The αβ dimer pairs were then aggregated into a quaternary structure through molecular dynamics simulations and energy minimization. The structure of LH-II, so determined, was an octamer of αβ heterodimers forming a ring with a diameter of 70Å. We discuss how the resulting structure may be used to solve the phase problem in X-ray crystallography in a procedure called molecular replacement.

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Structure and Function of Light‐harvesting Complexes and Their Polypeptides

Cited by 177 publications

References 185 publications

Predicting the structure of the light-harvesting complex II ofrhodospirillum molischianum

Predicting the structure of the light-harvesting complex II ofrhodospirillum molischianum

Differential expression of six light-harvesting chlorophyll a/b binding protein genes in maize leaf cell types.

Knowledge based structure prediction of the light-harvesting complex II of rhodospirillum molischianum

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