PLANT PHYSIOLOGY , Vol 106, Issue 2 747-754, Copyright © 1994 by American Society of Plant Biologists
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ENVIRONMENTAL AND STRESS PHYSIOLOGY |
Evidence for a Transient Association of New Proteins with the Spirulina maxima Phycobilisome in Relation to Light Intensity
F. Garnier, J. P. Dubacq and J. C. Thomas
Laboratoire de Photoregulation et Dynamique des Membranes Vegetales, Ecole Normale Superieure, Centre National de la Recherche Scientifique Unite de Recherche Associee 1810, Groupement de Recherche 1002, 46 Rue d'Ulm, 75230 Paris Cedex 05, France
Environmental parameters are known to affect phycobilisomes. Variations of
their structure and relative composition in phycobiliproteins have been
observed. We studied the effect of irradiance variations on the
phycobilisome structure in the cyanobacterium Spirulina maxima and
discovered the appearance of new polypeptides associated with the
phycobilisomes under an increased light intensity. In high light, the six
rods of phycocyanin associated with the central core of allophycocyanin
contained only one to two phycocyanin hexamers instead of the two to three
they contained in low light. The concomitant disappearance of a 33-kD
linker polypeptide was observed. Moreover, in high light three polypeptides
of 29, 30, and 47 kD, clearly unrelated to linkers, were found to be
associated with the phycobilisome fraction: protein labeling showed that a
specific association of these polypeptides was induced by high light. One
polypeptide, at least, would play the role of a chaperone protein. Not only
the synthesis of these proteins, which appeared slightly increased in high
light, but also their association with phycobilisome structure are light
intensity dependent.
