Mutations at ARG-342 in the chlorophyll binding protein CP43 affect growth and oxygen evolving activity in Synechocystis / by William R. Franch.
| Author/creator | Franch, William R. author. |
| Other author | Putnam-Evans, Cindy, degree supervisor. |
| Other author | East Carolina University. Department of Biology. |
| Format | Theses and dissertations |
| Production | 2007. |
| Description | 89 leaves : illustrations ; 28 cm |
| Supplemental Content | Access via ScholarShip |
| Subjects |
| Summary | Photosynthesis is the process by which cyanobacteria, algae, and higher plants convert light energy to chemical energy in the biosynthesis of carbohydrate. Photosystem II (PSII) is a multi-protein/ pigment complex that catalyzes the initial events of photosynthesis. These are the light driven transfer of electrons from water to plastoquinone, and concomitant production of molecular oxygen. The psbC gene product is the chlorophyll-binding protein CP43, an intrinsic component of PSII. CP43 is essential for water oxidation at the tetramanganese complex of the oxygen-evolving center (OEC). CP43 contains six membrane-spanning alpha helices flanked by a number of hydrophilic loops. The fifth hydrophilic loop of CP43, the large extrinsic loop E (LEL), appears to contain ligands to the manganese cluster. The residue E339 may be a direct ligand to one of the manganese ions. R342 may be a ligand to substrate water or bicarbonate, which may be hydrogen bonded to one of the manganese ions. McEvoy and Brudvig (2004) proposed that the guanidinium side chain of R342 abstracts protons from substrate water, then deprotonates to bulk solvent, thus contributing to the S-state mechanism responsible for oxygen evolution. Mutation of R342 to serine abolished photoautotrophic growth and oxygen-evolving activity in the model organism Synechocystis sp. PCC 6803 (Knoepfle et al. 1999). The goal of this study is to produce histidine, lysine, and alanine mutations at the R342 position, and assess their effects on PSII function. A variety of biochemical and biophysical techniques was used. None of the introduced mutations produced mutants that were able to grow photoautotrophically or evolve oxygen, though they did exhibit some capacity for charge separation as evidenced by the presence of variable fluorescence. The results strengthen the hypothesis that R342 is intimately involved in the water splitting reaction. |
| General note | Presented to the faculty of the Department of Biology. |
| General note | Advisor: Cindy Putnam-Evans |
| Dissertation note | M.S. East Carolina University 2007 |
| Bibliography note | Includes bibliographical references (leaves 80-89). |
| Genre/form | dissertations. |
| Genre/form | Academic theses. |
| Genre/form | Academic theses. |
| Genre/form | Thèses et écrits académiques. |
Availability
| Library | Location | Call Number | Status | Item Actions |
|---|---|---|---|---|
| Joyner | University Archives | ASK AT SPECIAL COLLECTIONS DESK | ✔ Available | Request Material |
| Electronic Resources | Access Content Online | ✔ Available |