Loading...
Please wait, while we are loading the content...
Similar Documents
GTP bound to chloroplast thylakoid membranes is required for light-induced, multienzyme degradation of the photosystem II D1 protein.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Spetea, Cornelia Hundal, Torill Lohmann, Felix Andersson, Bertil |
| Copyright Year | 1999 |
| Abstract | Even though light is the driving force in photosynthesis, it also can be harmful to plants. The water-splitting photosystem II is the main target for this light stress, leading to inactivation of photosynthetic electron transport and photooxidative damage to its reaction center. The plant survives through an intricate repair mechanism involving proteolytic degradation and replacement of the photodamaged reaction center D1 protein. Based on experiments with isolated chloroplast thylakoid membranes and photosystem II core complexes, we report several aspects concerning the rapid turnover of the D1 protein. (i) The primary cleavage step is a GTP-dependent process, leading to accumulation of a 23-kDa N-terminal fragment. (ii) Proteolysis of the D1 protein is inhibited below basal levels by nonhydrolyzable GTP analogues and apyrase treatment, indicating the existence of endogenous GTP tightly bound to the thylakoid membrane. This possibility was corroborated by binding studies. (iii) The proteolysis of the 23-kDa primary degradation fragment (but not of the D1 protein) is an ATP- and zinc-dependent process. (iv) D1 protein degradation is a multienzyme event involving a strategic (primary) protease and a cleaning-up (secondary) protease. (v) The chloroplast FtsH protease is likely to be involved in the secondary degradation steps. Apart from its significance for understanding the repair of photoinhibition, the discovery of tightly bound GTP should have general implications for other regulatory reactions and signal transduction pathways associated with the photosynthetic membrane. |
| File Format | PDF HTM / HTML |
| DOI | 10.1073/pnas.96.11.6547 |
| PubMed reference number | 10339625 |
| Journal | Medline |
| Volume Number | 96 |
| Issue Number | 11 |
| Alternate Webpage(s) | http://life.nthu.edu.tw/~b830356/LS6901/6547.pdf |
| Journal | Proceedings of the National Academy of Sciences of the United States of America |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
