On the role of the N-terminus of the extrinsic 33 kDa protein of Photosystem II.
The role of the N-terminus of the extrinsic 33 kDa protein of Photosystem II has been investigated by means of site-directed mutagenesis and cross-linking. Replacement of Asp-9 resulted in a dramatic increase in proteolytic sensitivity leading to the degradation of the protein forming a 31 kDa fragment with an undefined N-terminus. This fragment was unable to restore oxygen evolution. However, the variants of the 33 kDa protein which remained intact could reconstitute oxygen evolution as effectively as the wild-type protein. Cross-linking experiments with a water-soluble carbodiimide revealed that mutagenesis of residue D9 led to the disruption of an intramolecular salt bridge. Therefore we suggest that the N-terminus of the 33 kDa protein is necessary for maintaining the binding ability of the protein to Photosystem II but might not be involved in binding itself.
Seidler
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A
CNRS URA 1290, Département de Biologie Cellulaire et Moléculaire, CEA Saclay, Gif-sur-Yvette, France.
Rutherford
A W
AW
Michel
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H
D000595:Amino Acid Sequence; D018076:DNA, Complementary; D006868:Hydrolysis; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010100:Oxygen / Q000378:metabolism; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics / Q000378:metabolism*; D045332:Photosystem II Protein Complex; D010944:Plants / Q000235:genetics / Q000378:metabolism
D018076:DNA, Complementary; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; C064388:oxygen-evolving complex, 33 kDa protein; D010100:Oxygen