Mutations responsible for high light sensitivity in an atrazine-resistant mutant ofSynechcystis6714
✍ Scribed by Diana L. Kirilovsky; Ghada Ajlani; Martine Picaud; Anne-Lise Etienne
- Book ID
- 104614037
- Publisher
- Springer
- Year
- 1989
- Tongue
- English
- Weight
- 692 KB
- Volume
- 13
- Category
- Article
- ISSN
- 0167-4412
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✦ Synopsis
The primary target of photoinhibition is the photosystem II reaction center. The process involves a reversible damage, followed by an irreversible inhibition ofphotosystem II activity. During cell exposition to high light intensity, the D 1 protein is specially degraded. An atrazine-resistant mutant of Synechocystis 6714, AzV, reaches the irreversible step of photoinhibition faster than wild-type cells. Two point mutations present in the psbA gene of AzV (coding for D1) lead to the modification of Phe 211 to Ser and Ala 251 to Val in D 1 . Transformation of wild-type cells with the A z V p s b A gene shows that these two mutations are sufficient to induce a faster photodamage of PSII. Other DCMU-and/or atrazine-resistant mutants do not differ from the wild type when photoinhibited. We conclude that the QB pocket is involved in PSII photodamage and we propose that the mutation of Ala 251 might be related to a lower rate of proteolysis of the D1 protein than in the wild type.