Low temperature absorption spectroscopy of barley mutants. Guassian deconvolution and fourth derivative analysis

Simpson, David J. W.

doi:10.1007/bf02983310

Cited by 8 publications

(2 citation statements)

References 25 publications

(41 reference statements)

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“…thylakoids were similar to wild type (Table I) was confirmed by Gaussian deconvolution of the low temperature absorption spectrum, which showed the loss of a chlorophyll a species absorbing at 683 nm, accounting for 36 out of every 500 molecules in wild type thylakoids (14).…”

Section: Thecytochromeand P7oocontent Of Viridis -H5supporting

confidence: 55%

The structure and function of the thylakoid membrane

Simpson

Wettstein

1989

Carlsberg Res. Commun.

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Thylakoid membranes are latemUy differentiated into appressed and non-appressed regions called grana and stroma lamellae. Pure stroma lamellae isolated from wild type maize and barley leaves contain photosystem I and its light-harvesting antennae, the cytoehrome b6/fcomplex and coupling factor. Maize stroma lamellae contained only 2% of the total photosystem II polypeptides found in whole thylakoids, and most of the small amount of the photosystem II light-harvesting complex (LHCII) was associated with photosystem I. These results were consistent with the low rates of photosystem II electron transport and low levels of the high potential form of cytochrome b-559. Immune blot assays indicated that about half of the low potential form of eytochrome b-559 in stroma lamellae was antigenically distinct from that derived from the high potential form. The amount of LHCII in stroma lamellae could be increased by exposing leaves to bright white light (state 2) prior to the isolation of stroma lamellae. This LHCII caused a 15% increase in photosystem I antenna size and was different from the LHCII found in grana lamellae, since it lacked a 26 kD polypeptide possibly involved in thylakoid appression. These results demonstrate that the migration of LHCII from appressecl to non-appressed lamellae as a result of changes in the relative amounts of energy absorbed by the 2 different photosystems, also occurs in vivo.The reaction centre core of photosystem I was isolated from barley thylakoids and its molecular weight determined to be 650 kD. Attack by various proteases cleaved it into fragments of less than 5 kD, although the complex was still photoactive. However, the kinetics of photo-oxidation of P700 under light-limiting conditions were slower after proteolysis, indicating less efficient energy transfer. In a barley mutant lacking photosystem I, a chlorophyll a species absorbing at 689 nm was lacking, accounting for about 30 molecules out of every 500 in wild type thylakoids.Finally, a mutant completely lacking photosystem II activity, viridis -m, has been examined. It contained only 4% of the photosystem II-containing EFs particles found in wild type thylakoids, and lacked a chlorophyll a species absorbing at 683 nm. Immune electron microscopy revealed that the u-subunit of cytochrome b-559 and the 33 kD polypeptide of the oxygen evolving complex were correctly located in appressed thylakoids, in spite of the lack of the major photosystem II core polypeptides. A double mutant, lacking both photosystem I1 and LHCII was found to contain grana, even though its thylakoids lacked the 2 complexes normally associated with maintenance of membrane appression in vivo.

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Section: Thecytochromeand P7oocontent Of Viridis -H5supporting

confidence: 55%

The structure and function of the thylakoid membrane

Simpson

Wettstein

1989

Carlsberg Res. Commun.

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“…Spectra were recorded from intact leaves and by solid dilution at 77 K as described by Simpson and von Wettstein (1980) and Simpson et al (1985). Spectral deconvolution into component Gaussian curves was performed with the programme RESOL (Simpson 1988).…”

Section: Methodsmentioning

confidence: 99%

Expression and organisation of antenna proteins in the light-and temperature-sensitive barley mutant chlorina-104

Knoetzel

Simpson

1991

Planta

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The nuclear gene mutant chlorina-(104) of barley (Hordeum vulgare L.) is chlorophyll-deficient when grown under high irradiance, particularly at low temperatures. Chlorina- (104) chloroplasts had fewer thylakoids than the wild type, and fewer appressed lamellae relative to non-appressed lamellae. The freeze-fracture ultrastructure showed a loss of particles from the protoplasmic fracture face of the stacked thylakoid region (PFs), consistent with the loss of most of the light-harvesting complex (LHC) II, and a loss of some of the large particles from the same face of the unstacked thylakoid region (PFu), indicating a loss of photosystem-I particles. The mutant is remarkable for the high density of particles on the exoplasmic fracture face of the unstacked thylakoid region (EFu), levels of which fell to normal after transfer to low light. The chlorophyll deficiency was shown to be primarily caused by the loss of LHCII and LHCI-680, with the consequent loss of much of the chlorophyll (Chl) b and the xanthophylls neoxanthin and lutein. The use of a monoclonal antibody which recognises the 23-kDa polypeptide of LHCI-680, confirmed that it was severely depleted in chloroplasts from chlorina-(104) grown under restrictive conditions. The 77 K fluorescence emission spectrum was characterised by a pronounced shoulder at 720 nm, arising from the photosystem-I reaction centre (CPI). Since fluorescence from CPI is normally quenched by LHCI-730, this indicates that LHCI-680 mediates excitation energy transfer between LHCI-730 and the reaction centre. After moving seedlings to permissive conditions, LHCII and LHCI-680 began to accumulate in the chlorotic leaves and the fluorescence emission spectrum resembled that of wild-type leaves. Measurement of the steady-state mRNA levels with specific Cab probes, showed no difference between wild type and mutant, indicating that control of LHCII and LHCI-680 accumulation was at a post-transcriptional level.

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Light-harvesting Complexes of Plants and Algae: Introduction, Survey and Nomenclature

Simpson

Knoetzel

Oxygenic Photosynthesis: The Light Reactions

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Low temperature absorption spectroscopy of barley mutants. Guassian deconvolution and fourth derivative analysis

Cited by 8 publications

References 25 publications

The structure and function of the thylakoid membrane

The structure and function of the thylakoid membrane

Expression and organisation of antenna proteins in the light-and temperature-sensitive barley mutant chlorina-104

Light-harvesting Complexes of Plants and Algae: Introduction, Survey and Nomenclature

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