Molecular interference of Cd2+ with Photosystem II
(2004) In Biochimica et Biophysica Acta - Bioenergetics 1659(1). p.19-31- Abstract
- Many heavy metals inhibit electron transfer reactions in Photosystem II (PSII). Cd2+ is known to exchange, with high affinity in a slow reaction, for the Ca2+ cofactor in the Ca/Mn cluster that constitutes the oxygen-evolving center. This results in inhibition of photosynthetic oxygen evolution. There are also indications that Cd2+ binds to other sites in PSII, potentially to proton channels in analogy to heavy metal binding in photosynthetic reaction centers from purple bacteria. In search for the effects of Cd2+-binding to those sites, we have studied how Cd2+ affects electron transfer reactions in PSII after short incubation times and in sites, which interact with Cd2+ with low affinity. Overall electron transfer and partial electron... (More)
- Many heavy metals inhibit electron transfer reactions in Photosystem II (PSII). Cd2+ is known to exchange, with high affinity in a slow reaction, for the Ca2+ cofactor in the Ca/Mn cluster that constitutes the oxygen-evolving center. This results in inhibition of photosynthetic oxygen evolution. There are also indications that Cd2+ binds to other sites in PSII, potentially to proton channels in analogy to heavy metal binding in photosynthetic reaction centers from purple bacteria. In search for the effects of Cd2+-binding to those sites, we have studied how Cd2+ affects electron transfer reactions in PSII after short incubation times and in sites, which interact with Cd2+ with low affinity. Overall electron transfer and partial electron transfer were studied by a combination of EPR spectroscopy of individual redox components, flash-induced variable fluorescence and steady state oxygen evolution measurements. Several effects of Cd2+ were observed: (i) the amplitude of the flash-induced variable fluorescence was lost indicating that electron transfer from Y-Z to P-680(+) was inhibited; (ii) Q(A)(-) to Q(B) electron transfer was slowed down; (iii) the S-2 state multiline EPR signal was not observable; (iv) steady state oxygen evolution was inhibited in both a high-affinity and a low-affinity site; (v) the spectral shape of the EPR signal from Q(A)(-)Fe(2+) was modified but its amplitude was not sensitive to the presence of Cd2+. In addition, the presence of both Ca2+ and DCMU abolished Cd2+-induced effects partially and in different sites. The number of sites for Cd2+ binding and the possible nature of these sites are discussed. (C) 2004 Elsevier B.V. All rights reserved. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/138662
- author
- Sigfridsson Clauss, Kajsa LU ; Bernat, Gabor LU ; Mamedov, Fikret LU and Styring, Stenbjörn LU
- organization
- publishing date
- 2004
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Biochimica et Biophysica Acta - Bioenergetics
- volume
- 1659
- issue
- 1
- pages
- 19 - 31
- publisher
- Elsevier
- external identifiers
-
- wos:000224938900002
- pmid:15511524
- scopus:7244223640
- ISSN
- 0005-2728
- DOI
- 10.1016/j.bbabio.2004.07.003
- language
- English
- LU publication?
- yes
- id
- e165ed32-fabc-43e7-b058-c32cdbf9b7be (old id 138662)
- date added to LUP
- 2016-04-01 16:25:15
- date last changed
- 2022-04-22 21:51:53
@article{e165ed32-fabc-43e7-b058-c32cdbf9b7be,
abstract = {{Many heavy metals inhibit electron transfer reactions in Photosystem II (PSII). Cd2+ is known to exchange, with high affinity in a slow reaction, for the Ca2+ cofactor in the Ca/Mn cluster that constitutes the oxygen-evolving center. This results in inhibition of photosynthetic oxygen evolution. There are also indications that Cd2+ binds to other sites in PSII, potentially to proton channels in analogy to heavy metal binding in photosynthetic reaction centers from purple bacteria. In search for the effects of Cd2+-binding to those sites, we have studied how Cd2+ affects electron transfer reactions in PSII after short incubation times and in sites, which interact with Cd2+ with low affinity. Overall electron transfer and partial electron transfer were studied by a combination of EPR spectroscopy of individual redox components, flash-induced variable fluorescence and steady state oxygen evolution measurements. Several effects of Cd2+ were observed: (i) the amplitude of the flash-induced variable fluorescence was lost indicating that electron transfer from Y-Z to P-680(+) was inhibited; (ii) Q(A)(-) to Q(B) electron transfer was slowed down; (iii) the S-2 state multiline EPR signal was not observable; (iv) steady state oxygen evolution was inhibited in both a high-affinity and a low-affinity site; (v) the spectral shape of the EPR signal from Q(A)(-)Fe(2+) was modified but its amplitude was not sensitive to the presence of Cd2+. In addition, the presence of both Ca2+ and DCMU abolished Cd2+-induced effects partially and in different sites. The number of sites for Cd2+ binding and the possible nature of these sites are discussed. (C) 2004 Elsevier B.V. All rights reserved.}},
author = {{Sigfridsson Clauss, Kajsa and Bernat, Gabor and Mamedov, Fikret and Styring, Stenbjörn}},
issn = {{0005-2728}},
language = {{eng}},
number = {{1}},
pages = {{19--31}},
publisher = {{Elsevier}},
series = {{Biochimica et Biophysica Acta - Bioenergetics}},
title = {{Molecular interference of Cd2+ with Photosystem II}},
url = {{http://dx.doi.org/10.1016/j.bbabio.2004.07.003}},
doi = {{10.1016/j.bbabio.2004.07.003}},
volume = {{1659}},
year = {{2004}},
}