Plant Molecular Biology 42: 345–351, 2000.
© 2000 Kluwer Academic Publishers. Printed in the Netherlands.
An Arabidopsis thaliana protein homologous to cyanobacterial
, Jenny Andersson
, Soo Jung Kim
and Grzegorz Jackowski
Umeå Plant Science Center, Department of Plant Physiology, Umeå University, 901 87 Umeå, Sweden (
Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK
(present address: Department of Biology, University of Pennsylvania, Philadelphia, USA);
Department of Plant Physiology, Adam Mickiewicz University, Al. Niepodleglosci 14, 61-713 Poznañ, Poland
Received 19 January 1999; accepted in revised form 27 October 1999
Key words: Arabidopsis thaliana, ELIP, EST, high light, HLIP, LHC protein
An Arabidopsis thaliana cDNA clone encoding a novel 110 amino acid thylakoid protein has been sequenced.
The in vitro synthesized protein is taken up by intact chloroplasts, inserted into the thylakoid membrane and the
transit peptide is cleaved off during this process. The mature protein is predicted to contain 69 amino acids, to
form one membrane-spanning α-helix and to have its N-terminus at the stromal side of the thylakoid membrane.
The protein showed similarity to the LHC, ELIP and PsbS proteins of higher plants, but more pronounced to the
high-light-inducible proteins (HLIPs) of cyanobacteria and red algae, to which no homologue previously has been
detected in higher plants. As for HLIP and ELIP, high light increases the mRNA levels of the corresponding gene.
Sequence comparisons indicate that the protein may bind chlorophyll and form dimers in the thylakoid membrane.
The level of expression of the protein seems to be far lower than that of normal PSI and PSII subunits.
In the photosynthetic light reaction, light-harvesting
complexes fulﬁl an important function. They are not
essential for photosynthesis but associated with a large
amount of antenna pigment molecules which, after
excitation, can transfer the excitation energy between
each other and ultimately to the photosynthetic reac-
tion centers (Jansson, 1994). Some proteins in the
‘cores’ of photosystem I (PSI), namely PsaA and
PsaB, and PSII (CP43 and CP47) bind also antenna
pigments, but the pigment/protein ratio is much higher
in the ‘peripheral antenna’ making light-harvesting
complexes a cost-efﬁcient way to maximize the har-
vesting of light quanta. When plants and cyanobac-
teria are grown under conditions where light is the
limiting factor for growth, a large proportion of the
The nucleotide sequence data reported will appear in the EMBL,
GenBank and DDBJ Nucleotide Sequence Databases under the
accession number AF054617.
proteins synthesized in the cell are consequently light-
Cyanobacteria and red algae have a water-soluble
light-harvesting complex, the phycobilisome, where
phycobilins (phycocyanin, allophycocyanin, phyco-
erythrin, etc.) are bound to the antenna polypeptides
via covalent bonds (Grossman et al., 1995). In green
algae and plants, however, the peripheral antenna
consists of light-harvesting chlorophyll a/b-binding
(LHC) proteins which, in addition to chlorophyll a and
chlorophyll b, also bind the photosynthetic carotenoid
molecules. The carotenoids are light-harvesting pig-
ments but have an additional, perhaps even more im-
portant function in the dissipation of excitation energy
during conditions of excess light. The mechanisms be-
hind the energy transfermechanisms in the antenna are
partially understood, whereas the molecular changes
that trigger the switch from the state of energy trans-
fer to energy dissipation in the antenna have not been
elucidated (Horton et al., 1996).