Lipid-protein Interactions in Crystals of Plant Light-harvesting Complex

Nußberger, Stephan; Dörr, Karoline; Wang, Da-Neng; Kühlbrandt, Werner

doi:10.1006/jmbi.1993.1591

Cited by 298 publications

(184 citation statements)

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“…The suppressor mutations in these lines may have introduced a change in the amino acid sequence of a protein that allows the protein to better maintain its function in fab1 thylakoids at 2°C. For example, PG is a component of the light-harvesting complex of PSII (LHCII) as determined by x-ray crystallography (Liu et al, 2004) and is required for oligomerization of the complexes (Nussberger et al, 1993). If the altered fatty acid composition of PG in the fab1 mutant compromised assembly or maintenance of LHCII at low temperatures, then a mutation in one of the genes encoding LHCII (Andersson et al, 2003) might alleviate the defect, at least partially.…”

Section: Discussionmentioning

confidence: 99%

A Suppressor of fab1 Challenges Hypotheses on the Role of Thylakoid Unsaturation in Photosynthetic Function

Barkan

Vijayan²,

Carlsson³

et al. 2006

Plant Physiology

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Leaf membrane lipids of the Arabidopsis (Arabidopsis thaliana) fatty acid biosynthesis 1 (fab1) mutant contain a 35% to 40% increase in the predominant saturated fatty acid 16:0, relative to wild type. This increase in membrane saturation is associated with loss of photosynthetic function and death of mutant plants at low temperatures. We have initiated a suppressor screen for mutations that allow survival of fab1 plants at 2°C. Five suppressor mutants identified in this screen all rescued the collapse of photosynthetic function observed in fab1 plants. While fab1 plants died after 5 to 7 weeks at 2°C, the suppressors remained viable after 16 weeks in the cold, as judged by their ability to resume growth following a return to 22°C and to subsequently produce viable seed. Three of the suppressors had changes in leaf fatty acid composition when compared to fab1, indicating that one mechanism of suppression may involve compensating changes in thylakoid lipid composition. Surprisingly, the suppressor phenotype in one line, S31, was associated with a further substantial increase in lipid saturation. The overall leaf fatty acid composition of S31 plants contained 31% 16:0 compared with 23% in fab1 and 17% in wild type. Biochemical and genetic analysis showed that S31 plants contain a new allele of fatty acid desaturation 5 (fad5), fad5-2, and are therefore partially deficient in activity of the chloroplast 16:0 D7 desaturase. A double mutant produced by crossing fab1 to the original fad5-1 allele also remained alive at 2°C, indicating that the fad5-2 mutation is the suppressor in the S31 (fab1 fad5-2) line. Based on the biophysical characteristics of saturated and unsaturated fatty acids, the increased 16:0 in fab1 fad5-2 plants would be expected to exacerbate, rather than ameliorate, low-temperature damage. We propose instead that a change in shape of the major thylakoid lipid, monogalactosyldiacylglycerol, mediated by the fad5-2 mutation, may compensate for changes in lipid structure resulting from the original fab1 mutation. Our identification of mutants that suppress the low-temperature phenotype of fab1 provides new tools to understand the relationship between thylakoid lipid structure and photosynthetic function.

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Section: Discussionmentioning

confidence: 99%

A Suppressor of fab1 Challenges Hypotheses on the Role of Thylakoid Unsaturation in Photosynthetic Function

Barkan

Vijayan²,

Carlsson³

et al. 2006

Plant Physiology

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“…A component that is required for LHCII trimer formation is phosphatidyl glycerol (41,42), and a specific requirement for this lipid containing 16:1-trans-hexadecenoic acid has been suggested (43); the latter is accumulated in plastids only during greening (44). We are presently testing whether the addition of this lipid or other lipids to pigment-supplemented etioplast membranes promotes the assembly of inserted pL-HCP or LHCP into trimeric LHCII.…”

Section: Discussionmentioning

confidence: 99%

Light-harvesting Chlorophyll a/b-binding Protein Stably Inserts into Etioplast Membranes Supplemented with Zn-pheophytina/b

Kuttkat¹,

Edhofer²,

Eichacker³

et al. 1997

Journal of Biological Chemistry

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Light-harvesting chlorophyll a/b-binding protein, LHCP, or its precursor, pLHCP, cannot be stably inserted into barley etioplast membranes in vitro. However, when these etioplast membranes are supplemented with the chlorophyll analogs Zn-pheophytin a/b, synthesized in situ from Zn-pheophorbide a/b and digeranyl pyrophosphate, pLHCP is inserted into a protease-resistant state. This proves that chlorophyll is the only component lacking in etioplast membranes that is necessary for stable LHCP insertion. Synthesis of Znpheophytin b alone promotes insertion of LHCP in vitro into a protease-resistant state, whereas synthesis of Znpheophytin a alone does not. Insertion of pLHCP into etioplast membranes can also be stimulated by adding chlorophyll a and chlorophyll b to the membranes, albeit at a significantly lower efficiency as compared with Zn-pheophytin a/b synthesized in situ. When pLHCP is inserted into chlorophyll-or Zn-pheophytin-supplemented etioplast membranes and then assayed with protease, only the protease digestion product indicative of the monomeric major light-harvesting chlorophyll a/b complex (LHCII) is found but not the one indicating trimeric complexes. In this respect, chlorophyll-or Znpheophytin-supplemented etioplast membranes resemble thylakoid membranes at an early greening stage: pLHCP inserted into plastid membranes from greening barley is assembled into trimeric LHCII only after more than 1 h of greening.

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“…Two positive bands at 662 and 686 nm accompany the negative band at 675 nm, and the asymmetry of the positive band at 686 nm suggests that the bands at 662 and 686 nm arise from a blue shift and a broadening of the 675 nm band. The 675 nm absorption in the trimeric LHCII is most likely from either Chl a 4 or Chl a 5 (52), which appear to be in close proximity to Lut2 (53). Thus, these differences in absorption spectrum between LHCII trimers and monomers can tentatively be attributed to a change in the Lut2/ Chl a 4 /Chl a 5 domain occurring upon monomerization.…”

Section: Pigment Composition Of Monomeric Lhciimentioning

confidence: 92%

“…This asymmetry imposed by trimerization is absent in monomers, and this then explains why the distinctive spectral property of Lut2 is lost, and Lut2 and Lut1 become indistinguishable. The change in configuration of Lut2 may then explain the alterations in the Chl a 4 and a 5 in the lutein 2 domain.…”

Section: Pigment Composition Of Monomeric Lhciimentioning

confidence: 99%

The Functional Significance of the Monomeric and Trimeric States of the Photosystem II Light Harvesting Complexes

2003

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The main light harvesting complex of photosystem II in plants, LHCII, exists in a trimeric state. To understand the biological significance of trimerization, a comparison has been made been LHCII trimers and LHCII monomers prepared by treatment with phospholipase. The treatment used caused no loss of chlorophyll, but there was a difference in carotenoid composition, together with the previously observed alterations in absorption spectrum. It was found that, when compared to monomers, LHCII trimers showed increased thermal stability and a reduced structural flexibility as determined by the decreased rate and amplitude of fluorescence quenching in low-detergent concentration. It is suggested that LHCII should be considered as having two interacting domains: the lutein 1 domain, the site of fluorescence quenching [Wentworth et al. (2003) J. Biol. Chem. 278, 21845-21850], and the lutein 2 domain. The lutein 2 domain faces the interior of the trimer, the differences in absorption spectrum and carotenoid binding in trimers compared to monomers indicating that the trimeric state modulates the conformation of this domain. It is suggested that the lutein 2 domain controls the conformation of the lutein 1 domain, thereby providing allosteric control of fluorescence quenching in LHCII. Thus, the pigment configuration and protein conformation in trimers is adapted for efficient light harvesting and enhanced protein stability. Furthermore, trimers exhibit the optimum level of control of energy dissipation by modulating the development of the quenched state of the complex.

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Lipid-protein Interactions in Crystals of Plant Light-harvesting Complex

Cited by 298 publications

References 0 publications

A Suppressor of fab1 Challenges Hypotheses on the Role of Thylakoid Unsaturation in Photosynthetic Function

A Suppressor of fab1 Challenges Hypotheses on the Role of Thylakoid Unsaturation in Photosynthetic Function

Light-harvesting Chlorophyll a/b-binding Protein Stably Inserts into Etioplast Membranes Supplemented with Zn-pheophytina/b

The Functional Significance of the Monomeric and Trimeric States of the Photosystem II Light Harvesting Complexes

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