TY - JOUR
T1 - Spectroscopic studies of phycobilisome subcore preparations lacking key core chromophores
T2 - Assignment of excited state energies to the Lcm, β18 and αAP-B chromophores
AU - Gindt, Yvonne M.
AU - Zhou, Jianhui
AU - Bryant, Donald A.
AU - Sauer, Kenneth
N1 - Funding Information:
The authorsw ould like to thank Crystal Chan and Dr. Craig Fairchildf or help with the HPLC. We benefitted from helpful discussionws ith Prof. A.N. Glazer and Dr. Martin DebreczenyT.h is work was supported by the Director,O ffice of Energy ResearchO, ffice of Basic EnergyS ciencesE, nergyB ioscienceDs ivision,o f the U.S. Departmenot f Energy under ContractN o. DE-AC03-76SF0009(8Y .M.G. and K.S.), and by the US Public Health Serviceg rantG M-31625( D.A.B).
PY - 1994/7/29
Y1 - 1994/7/29
N2 - Chromophore absorption and emission characteristics of the αAP-B, β18 and Lcm (large core-membrane linker) chromopeptides within the phycobilisome core are investigated using genetically engineered strains of Synechococcus sp. PCC 7002. Steady-state and time-resolved emission were used to examine energy transfer in subcore preparations from the wild-type organism and two mutants. Low-temperature (77 K) emission spectra were also measured for intact phycobilisomes from the wild-type and five mutant strains. Mutants retaining either the αAP-B subunit or the unaltered Lcm chromophore resulted in only small changes in the low-temperature emission spectra, while retention of only the β18 subunit resulted in blue-shifted emission spectra. The Lcm chromophore has a room-temperature absorption maximum at 675 nm. In phycobilisomes at 77 K the αAP-B and Lcm chromophores emit at 682-683 nm, and they are the best candidates for long-wavelength emitters also at room temperature. Overlap of these emission spectra with the absorption of chlorophyll a in the associated thylakoid membrane plays a significant role in excitation transfer from the antenna complexes in cyanobacteria.
AB - Chromophore absorption and emission characteristics of the αAP-B, β18 and Lcm (large core-membrane linker) chromopeptides within the phycobilisome core are investigated using genetically engineered strains of Synechococcus sp. PCC 7002. Steady-state and time-resolved emission were used to examine energy transfer in subcore preparations from the wild-type organism and two mutants. Low-temperature (77 K) emission spectra were also measured for intact phycobilisomes from the wild-type and five mutant strains. Mutants retaining either the αAP-B subunit or the unaltered Lcm chromophore resulted in only small changes in the low-temperature emission spectra, while retention of only the β18 subunit resulted in blue-shifted emission spectra. The Lcm chromophore has a room-temperature absorption maximum at 675 nm. In phycobilisomes at 77 K the αAP-B and Lcm chromophores emit at 682-683 nm, and they are the best candidates for long-wavelength emitters also at room temperature. Overlap of these emission spectra with the absorption of chlorophyll a in the associated thylakoid membrane plays a significant role in excitation transfer from the antenna complexes in cyanobacteria.
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U2 - 10.1016/0005-2728(94)90174-0
DO - 10.1016/0005-2728(94)90174-0
M3 - Article
C2 - 8043589
AN - SCOPUS:0028018301
SN - 0005-2728
VL - 1186
SP - 153
EP - 162
JO - Biochimica et Biophysica Acta - Bioenergetics
JF - Biochimica et Biophysica Acta - Bioenergetics
IS - 3
ER -