TY - JOUR
T1 - Structural and functional changes of PSI-LHCI supercomplexes of Chlamydomonas reinhardtii cells grown under high salt conditions
AU - Subramanyam, Rajagopal
AU - Jolley, Craig
AU - Thangaraj, Balakumar
AU - Nellaepalli, Sreedhar
AU - Webber, Andrew
AU - Fromme, Petra
N1 - Funding Information:
Acknowledgments This work was supported by Department of Biotechnology (BT/PR11277/GBD/27/152/2008), Department of Science and technology, India to RS and the National Science Foundation under Grant No. MCB-0417142. We thank Prof. Kevin Redding, Department of Chemistry and Biochemistry, Arizona State University, USA for his kind gift of the antibodies (PsaE and F). We thank Dr. Su Lin for assistance with the Xuorescence kinetics measurements at the Center for Bio-optical Nanotechnology at ASU.
PY - 2010/3
Y1 - 2010/3
N2 - The effect of high salt concentration (100 mM NaCl) on the organization of photosystem I-light harvesting complex I supercomplexes (PSI-LHCI) of Chlamydomonas reinhardtii was studied. The electron transfer activity was reduced by 39% in isolated PSI-LHCI supercomplexes. The visible circular dichroism (CD) spectra associated with strongly coupled chlorophyll (Chl) dimers were reduced in intensity, indicating that pigment-pigment interactions were disrupted. This data is consistent with results from fluorescence streak camera spectroscopy, which suggest that red-shifted pigments in the PSI-LHCI antenna had been lost. Denaturing gel electrophoresis and immunoblot analysis reveals that levels of the PSI reaction center proteins PsaD, PsaE and PsaF were reduced due to salt stress. PsaE is almost completely absent under high salt conditions. It is known that the membrane-extrinsic subunits PsaD and E form the ferredoxin-docking site. Our results indicate that the PSI-LHCI supercomplex is damaged by reactive oxygen species at high salt concentration, with particular impact on the ferredoxin-docking site and the PSI-LHCI interface.
AB - The effect of high salt concentration (100 mM NaCl) on the organization of photosystem I-light harvesting complex I supercomplexes (PSI-LHCI) of Chlamydomonas reinhardtii was studied. The electron transfer activity was reduced by 39% in isolated PSI-LHCI supercomplexes. The visible circular dichroism (CD) spectra associated with strongly coupled chlorophyll (Chl) dimers were reduced in intensity, indicating that pigment-pigment interactions were disrupted. This data is consistent with results from fluorescence streak camera spectroscopy, which suggest that red-shifted pigments in the PSI-LHCI antenna had been lost. Denaturing gel electrophoresis and immunoblot analysis reveals that levels of the PSI reaction center proteins PsaD, PsaE and PsaF were reduced due to salt stress. PsaE is almost completely absent under high salt conditions. It is known that the membrane-extrinsic subunits PsaD and E form the ferredoxin-docking site. Our results indicate that the PSI-LHCI supercomplex is damaged by reactive oxygen species at high salt concentration, with particular impact on the ferredoxin-docking site and the PSI-LHCI interface.
KW - Chlamydomonas
KW - Excitation energy
KW - Light harvesting complexes
KW - PSI-LHCI supercomplexes
KW - Photosystem I core
KW - Reactive oxygen species
KW - Salt stress
KW - Superoxide dismutase
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U2 - 10.1007/s00425-009-1097-x
DO - 10.1007/s00425-009-1097-x
M3 - Article
C2 - 20183922
AN - SCOPUS:77950539802
SN - 0032-0935
VL - 231
SP - 913
EP - 922
JO - Planta
JF - Planta
IS - 4
ER -