Calcium Binding to the Photosystem II Subunit CP29
| Autor: | A. William Rutherford, Roberto Bassi, Caroline Jegerschöld, Tony A. Mattioli, Massimo Crimi |
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| Rok vydání: | 2000 |
| Předmět: |
Models
Molecular Spectrophotometry Infrared Photosystem II Protein subunit Molecular Sequence Data Photosynthetic Reaction Center Complex Proteins Population Light-Harvesting Protein Complexes chemistry.chemical_element Calcium Zea mays Biochemistry Protein Structure Secondary Fluorescence spectroscopy Amino Acid Sequence Ytterbium Binding site education Molecular Biology Ions education.field_of_study Binding Sites Chemistry Temperature Photosystem II Protein Complex Cell Biology Glutamic acid Hydrogen-Ion Concentration Crystallography Dicyclohexylcarbodiimide Helix Metals Rare Earth Protein Binding |
| Zdroj: | Karolinska Institutet |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.275.17.12781 |
| Popis: | We have identified a Ca(2+)-binding site of the 29-kDa chlorophyll a/b-binding protein CP29, a light harvesting protein of photosystem II most likely involved in photoregulation. (45)Ca(2+) binding studies and dot blot analyses of CP29 demonstrate that CP29 is a Ca(2+)-binding protein. The primary sequence of CP29 does not exhibit an obvious Ca(2+)-binding site therefore we have used Yb(3+) replacement to analyze this site. Near-infrared Yb(3+) vibronic side band fluorescence spectroscopy (Roselli, C., Boussac, A., and Mattioli, T. A. (1994) Proc. Natl. Acad. Sci. U. S. A. 91, 12897-12901) of Yb(3+)-reconstituted CP29 indicated a single population of Yb(3+)-binding sites rich in carboxylic acids, characteristic of Ca(2+)-binding sites. A structural model of CP29 presents two purported extra-membranar loops which are relatively rich in carboxylic acids, one on the stromae side and one on the lumenal side. The loop on the lumenal side is adjacent to glutamic acid 166 in helix C of CP29, which is known to be the binding site for dicyclohexylcarbodiimide (Pesaresi, P., Sandonà, D., Giuffra, E. , and Bassi, R. (1997) FEBS Lett. 402, 151-156). Dicyclohexylcarbodiimide binding prevented Ca(2+) binding, therefore we propose that the Ca(2+) in CP29 is bound in the domain including the lumenal loop between helices B and C. |
| Databáze: | OpenAIRE |
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