Characterization of the stromal protease(s) degrading the cross-linked products of the D1 protein generated by photoinhibition of photosystem II
| Autor: | Noriaki Tamura, Saori Abe, Yoji Nishi, Takahiro Henmi, Yasusi Yamamoto, Ali Ferjani, Yuka Tomokawa, Yasuo Ishikawa |
|---|---|
| Rok vydání: | 2001 |
| Předmět: |
Serine Proteinase Inhibitors
Stromal cell Photoinhibition Light GTP' Cytochrome Photosystem II medicine.medical_treatment Photosynthetic Reaction Center Complex Proteins Biophysics D1 protein Cytochrome b559 Biochemistry Endopeptidases medicine Protease Inhibitors Cross-linked product Stromal protease Photosystem Protease biology Nucleotides Apyrase Chemistry Photosystem II Protein Complex Cell Biology Hydrogen-Ion Concentration Cytochrome b Group Enzyme Activation Oxygen biology.protein Protein Binding |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Bioenergetics. 1503(3):385-395 |
| ISSN: | 0005-2728 |
| DOI: | 10.1016/s0005-2728(00)00233-4 |
| Popis: | When photosystem (PS) II-enriched membranes are exposed to strong light, cross-linking of the intrinsic D1 protein with the surrounding polypeptides and degradation of the D1 protein take place. The cross-linking of the D1 protein with the alpha-subunit of cytochrome b(559) is suggested to be an early event of photoinduced damage to the D1 protein (Barbato et al., FEBS Lett. 309 (1992) 165-169). The relationship between the cross-linking and the degradation of the D1 protein, however, is not yet clear. In the present study, we show that the addition of stromal extract from chloroplasts degrades the 41 kDa cross-linked product of D1/cytochrome b(559) alpha-subunit and enhances the degradation of the D1 protein. Incubation of the preilluminated PS II-enriched membranes with the stromal extract at 25 degrees C causes the degradation of the cross-linked product by more than 70%. The activity of the stromal extract showed a pH optimum at 8.0, and was enhanced by the addition of ATP or GTP. Consistent with the nucleotide effect, this stromal activity was eliminated by the preincubation of the stromal extract with apyrase, which hydrolyzes nucleotides. Also, the stromal activity was nearly fully inhibited by a serine-type protease inhibitor, 3,4-dichloroisocoumarin, which suggests participation of a serine-type protease(s). |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect