Chlorophyll b is involved in long-wavelength spectral properties of light-harvesting complexes LHC I and LHC II.
Chlorophyll (Chl) molecules attached to plant light-harvesting complexes (LHC) differ in their spectral behavior. While most Chl a and Chl b molecules give rise to absorption bands between 645 nm and 670 nm, some special Chls absorb at wavelengths longer than 700 nm. Among the Chl a/b-antennae of higher plants these are found exclusively in LHC I. In order to assign this special spectral property to one chlorophyll species we reconstituted LHC of both photosystem I (Lhca4) and photosystem II (Lhcb1) with carotenoids and only Chl a or Chl b and analyzed the effect on pigment binding, absorption and fluorescence properties. In both LHCs the Chl-binding sites of the omitted Chl species were occupied by the other species resulting in a constant total number of Chls in these complexes. 77-K spectroscopic measurements demonstrated that omission of Chl b in refolded Lhca4 resulted in a loss of long-wavelength absorption and 730-nm fluorescence emission. In Lhcb1 with only Chl b long-wavelength emission was preserved. These results clearly demonstrate the involvement of Chl b in establishing long-wavelength properties.
Schmid
V H
VH
Institut für Allgemeine Botanik, Johannes-Gutenberg Universität, Mainz, Germany. vschmid@mail.uni-mainz.de
Thomé
P
P
Rühle
W
W
Paulsen
H
H
Kühlbrandt
W
W
Rogl
H
H
D000042:Absorption; D001665:Binding Sites; D002499:Centrifugation, Density Gradient; D002734:Chlorophyll / Q000737:chemistry / Q000378:metabolism*; D000077194:Chlorophyll A; D045342:Light-Harvesting Protein Complexes; D018551:Solanum lycopersicum; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry* / Q000378:metabolism*; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D010860:Pigments, Biological / Q000032:analysis / Q000737:chemistry; D018515:Plant Leaves; D011485:Protein Binding; D013050:Spectrometry, Fluorescence; D018724:Spinacia oleracea; D013696:Temperature
D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D010860:Pigments, Biological; D002734:Chlorophyll; C037184:chlorophyll b; D000077194:Chlorophyll A