The secondary structure of the 33 kDa manganese-stabilizing protein from Anacystis nidulans R2 was predicted using information from a family of homologous sequences and applying the algorithms of Williams et al. and Zvelebil et al. From the sequence conservation and the predicted secondary structure, nine functionally important domains were identified. Additional algorithms predicted potential antigenic determinants and a region that may serve to bind this polypeptide to the Photosystem II core complex. One of the functionally significant regions exhibits partial sequence similarity to the Mn-binding site of the bacterial superoxide dismutase and was targeted for site-directed mutagenesis. Two aspartic acid residues in this region, which may form carboxyl bridges to stabilize Mn ions, were subjected to saturation mutagenesis. A hybrid vector which affords temperature regulated expression of a cloned gene, was constructed to introduce the various forms of the mutated gene into the cyanobacterium, A. nidulans R2. Pools of Eschericia coli and A. nidulans cells harboring mutant polypeptides have been obtained. Some mutant cyanobacteria display altered pigmentation and differences in generation time dependent upon growth temperature suggesting a functionally significant residue has indeed been altered. Future studies will be concerned with the characterization of specific mutants in order to determine the relationship between the structure and function of this polypeptide. / Department of Biology
| Identifer | oai:union.ndltd.org:BSU/oai:cardinalscholar.bsu.edu:handle/179954 |
| Date | January 1989 |
| Creators | Read, Betsy A. |
| Contributors | Vann, Carolyn N. |
| Source Sets | Ball State University |
| Detected Language | English |
| Format | vii, 102 leaves : ill. ; 28 cm. |
| Source | Virtual Press |
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