TY  - JOUR
A1  - Standfuß, Jörg
A1  - Kühlbrandt, Werner
T1  - The three isoforms of the light-harvesting complex II: spectroscopic features, trimer formation, and functional roles
T2  - Journal of biological chemistry
N2  - The major light-harvesting complex (LHC-II) of higher plants plays a crucial role in capturing light energy for photosynthesis and in regulating the flow of energy within the photosynthetic apparatus. Native LHC-II isolated from plant tissue consists of three isoforms, Lhcb1, Lhcb2, and Lhcb3, which form homo- and heterotrimers. All three isoforms are highly conserved among different species, suggesting distinct functional roles. We produced the three LHC-II isoforms by heterologous expression of the polypeptide in Escherichia coli and in vitro refolding with purified pigments. Although Lhcb1 and Lhcb2 are very similar in polypeptide sequence and pigment content, Lhcb3 is clearly different because it lacks an N-terminal phosphorylation site and has a higher chlorophyll a/b ratio, suggesting the absence of one chlorophyll b. Low temperature absorption and fluorescence emission spectra of the pure isoforms revealed small but significant differences in pigment organization. The oligomeric state of the pure isoforms and of their permutations was investigated by native gel electrophoresis, sucrose density gradient centrifugation, and SDS-PAGE. Lhcb1 and Lhcb2 formed trimeric complexes by themselves and with one another, but Lhcb3 was able to do so only in combination with one or both of the other isoforms. We conclude that the main role of Lhcb1 and Lhcb2 is in the adaptation of photosynthesis to different light regimes. The most likely role of Lhcb3 is as an intermediary in light energy transfer from the main Lhcb1/Lhcb2 antenna to the photosystem II core.
Y1  - 2021
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/76163
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-761638
SN  - 0021-9258
VL  - 279.2004
IS  - 35
SP  - 36884
EP  - 36891
PB  - American Society for Biochemistry and Molecular Biology Publications
CY  - Bethesda, Md
ER  -