Decrease of polypeptides in the PS I antenna complex with increasing growth irradiance in the red alga Porphyridium cruentum |
| |
Authors: | Shi Tan Gregory R Wolfe Francis X Cunningham Jr Elisabeth Gantt |
| |
Institution: | (1) Department of Plant Biology, University of Maryland, 20742 College Park, MD, USA;(2) Maryland Agricultural Experiment Station, University of Maryland, 20742 College Park, MD, USA;(3) Department of Botany, Arizona State University, 85287 Tempe, AZ, USA |
| |
Abstract: | Thylakoids isolated from cells of the red alga Porphyridium cruentum exhibit an increased PS I activity on a chlorophyll basis with increasing growth irradiance, even though the stoichiometry of Photosystems I and II in such cells shows little change (Cunningham et al. (1989) Plant Physiol 91: 1179–1187). PS I activity was 26% greater in thylakoids of cells acclimated at 280 mol photons · m–2 · s–1 (VHL) than in cells acclimated at 10 mol photons · m–2 · s–1 (LL), indicating a change in the light absorbance capacity of PS I. Upon isolating PS I holocomplexes from VHL cells it was found that they contained 132±9 Chl/P700 while those obtained from LL cells had 165±4 Chl/P700. Examination of the polypeptide composition of PS I holocomplexes on SDS-PAGE showed a notable decrease of three polypeptides (19.5, 21.0 and 22 kDa) in VHL-complexes relative to LL-complexes. These polypeptides belong to a novel LHC I complex, recently discovered in red algae (Wolfe et al. (1994a) Nature 367: 566–568), that lacks Chl b and includes at least six different polypeptides. We suggest that the decrease in PS I Chl antenna size observed with increasing irradiance is attributable to changes occurring in the LHC I-antenna complex. Evidence for a Chl-binding antenna complex associated with PS II core complexes is lacking at this point. LHC II-type polypeptides were not observed in functionally active PS II preparations (Wolfe et al. (1994b) Biochimica Biophysica Acta 1188: 357–366), nor did we detect polypeptides that showed immunocross-reactivity with LHC II specific antisera (made to Chlamydomonas and Euglena LHC II).Abbreviations Bis-Tris
bis(2-hydroxyethyl)imino-tris(hydroxymethyl)methane
- DCPIP
2,6-dichlorophenol indophenol
- -dm
dodecyl--d-maltoside
- HL
high light of 150 mol photons · m–2 · s–1
- LGB
lower green band
- LHC I
light-harvesting complex of PS I
- LHC II
light-harvesting complex of PS II
- LL
low light of 10 mol photons · m–2 · s–1
- ML
medium light of 50 mol photons · m–2 · s–1
- MES
2-(N-morpholino) ethanesulfonic acid
- P700
reaction center of PS I
- PFD
photon flux density
- Trizma
tris(hydroxymethyl)aminomethane
- UGB
upper green band
- VHL
very high light of 280 mol photons · m–2 · s–1 |
| |
Keywords: | light-harvesting antenna Mehler reaction Photosystem I Porphyridium |
本文献已被 SpringerLink 等数据库收录! |
|