Fine Tuning of Chlorophyll Spectra by Protein-Induced Ring Deformation.
The ability to tune the light-absorption properties of chlorophylls by their protein environment is the key to the robustness and high efficiency of photosynthetic light-harvesting proteins. Unfortunately, the intricacy of the natural complexes makes it very difficult to identify and isolate specific protein-pigment interactions that underlie the spectral-tuning mechanisms. Herein we identify and demonstrate the tuning mechanism of chlorophyll spectra in type II water-soluble chlorophyll binding proteins from Brassicaceae (WSCPs). By comparing the molecular structures of two natural WSCPs we correlate a shift in the chlorophyll red absorption band with deformation of its tetrapyrrole macrocycle that is induced by changing the position of a nearby tryptophan residue. We show by a set of reciprocal point mutations that this change accounts for up to 2/3 of the observed spectral shift between the two natural variants.
Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel.
Dominika
D
Bednarczyk
Israel Structural Proteomics Center, Weizmann Institute of Science, Rehovot, Israel.
Orly
O
Dym
Migal-Galilee Research Institute, S. Industrial Zone, Kiryat Shmona, Israel.
Vadivel
V
Prabahar
Israel Structural Proteomics Center, Weizmann Institute of Science, Rehovot, Israel.
Yoav
Y
Peleg
Department of Biochemistry and Molecular Biology and the Center for Advanced Biotechnology and Medicine, Robert Wood Johnson Medical School, Rutgers University, 679 Hoes Lane West, Piscataway, NJ, 08854, USA.
Douglas H
DH
Pike
Migal-Galilee Research Institute, S. Industrial Zone, Kiryat Shmona, Israel. drorn@migal.org.il.
Dror
D
Noy
D019607:Brassicaceae / Q000737:chemistry; D002734:Chlorophyll / Q000737:chemistry*; D061146:Chlorophyll Binding Proteins / Q000737:chemistry* / Q000235:genetics; D008027:Light; D008958:Models, Molecular; D015394:Molecular Structure; D017354:Point Mutation
D061146:Chlorophyll Binding Proteins; D002734:Chlorophyll
chlorophyll; light-harvesting complexes; spectral tuning; structure determination; water soluble chlorophyll binding protein