EurekaMag.com logo
+ Site Statistics
References:
52,725,316
Abstracts:
28,411,598
+ Search Articles
+ Subscribe to Site Feeds
EurekaMag Most Shared ContentMost Shared
EurekaMag PDF Full Text ContentPDF Full Text
+ PDF Full Text
Request PDF Full TextRequest PDF Full Text
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter
Follow on Google+Follow on Google+
Follow on LinkedInFollow on LinkedIn

+ Translate

Identification of proton-active residues in a higher plant light-harvesting complex


Proceedings of the National Academy of Sciences of the United States of America, 93(24): 14204-14209
Identification of proton-active residues in a higher plant light-harvesting complex
The thermal dissipation of absorbed light energy by the light-harvesting apparatus of higher plants is important in protecting the photosynthetic machinery from the effects of excess illumination. A major mechanism for such photoprotection, known as trans-thylakoid deltapH-dependent chlorophyll fluorescence quenching (qE), is induced by acidification of the lumen, is correlated with the interconversion of xanthophyll pigments, and is manifested as quenching of chlorophyll fluorescence. The mechanistic basis for qE remains unknown. The reagent N,N'-dicyclohexylcarbodiimide (DCCD) specifically inhibits qE and covalently binds to two minor light-harvesting pigment-protein complexes (LHCII), LHCIIa and LHCIIc. It is shown that DCCD treatment of isolated LHCIIc complexes reverses acid-induced chlorophyll fluorescence quenching in an in vitro system. Fingerprinting of [14C]DCCD-labeled LHCIIc demonstrates that there are two DCCD-sensitive amino acid residues on this complex, and these are shown to be glutamate residues, each of which is located near the lumen. In view of the effects of DCCD on the pattern of proton release from photosystem II during photosynthesis, we propose a model for the mechanism of the induction of qE--that these residues form part of a proton pathway, the lumen pH being sensed via its effects on the rate of proton release. One possibility is that the resulting changes in the protonation state of these carboxyl side chains may modulate the structural and energetic organization of LHCII.

Accession: 002863724

PMID: 8943085

DOI: 10.2307/41051

Download PDF Full Text: Identification of proton-active residues in a higher plant light-harvesting complex



Related references

Single-molecule electron tunneling spectroscopy of the higher plant light-harvesting complex LHC II. Biochemical and Biophysical Research Communications 256(2): 288-292, 1999

Orientation of chlorophyll transition moments in the higher-plant light-harvesting complex CP29. Biochemistry 38(40): 12974-12983, 1999

Orientation of chlorophyll transition moments in the higher-plant light-harvesting complex CP29. Biochemistry (American Chemical Society) 38(40): 974-83, 1999

Separation of polypeptides containing chlorophylls a and b in the light harvesting chlorophyll a b protein complex from higher plant chloroplasts. Biokhimiya 49(8): 1383-1385, 1984

Assignment of spectral substructures to pigment-binding sites in higher plant light-harvesting complex LHC-II. Biochemistry (American Chemical Society) 41(7): 81-7, 2002

Assignment of spectral substructures to pigment-binding sites in higher plant light-harvesting complex LHC-II. Biochemistry 41(7): 2281-2287, 2002

Configuration and dynamics of xanthophylls in light-harvesting antennae of higher plants. Spectroscopic analysis of isolated light-harvesting complex of photosystem II and thylakoid membranes. Journal of Biological Chemistry 276(27): 24862-24870, 2001

Xanthophylls in light-harvesting complex II of higher plants: light harvesting and triplet quenching. Biochemistry 36(40): 12208-12215, 1997

Universality of poly peptides from the pigment protein complex of photosystem i and the light harvesting chlorophyll a b protein complex in higher plant chloroplasts. Biokhimiya 48(6): 1052-1054, 1983

Light-harvesting complex II pigments and proteins in association with Cbr, a homolog of higher-plant early light-inducible proteins in the unicellular green alga Dunaliella. Planta 210(6): 947-955, 2000