In vitro assembly of apophytochrome and apophytochrome deletion mutants expressed in yeast with phycocyanobilin. |
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| Authors: | L Deforce K Tomizawa N Ito D Farrens P S Song M Furuya |
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| Affiliation: | Plant Biological Regulation, Frontier Research Program, RIKEN, Saitama, Japan. |
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| Abstract: | Recombinant pea type I phytochrome apoprotein expressed in yeast is shown to assemble in vitro with phycocyanobilin to produce a photoreversible phytochrome-like adduct. As an initial investigation of the amino acid sequence requirements for chromophore incorporation, three phyA gene product deletion mutants were produced in yeast. Truncation of the N-terminal tail to residue 46 demonstrates that this region is not critical to bilin attachment, but a deletion mutant lacking 222 amino acids from the N terminus failed to yield holophytochrome in vitro, under the same conditions. A mutant comprising a deletion of the C terminus to residue 548 showed bilin incorporation and red/far-red photoreversibility, indicating that bilin-apophytochrome assembly still occurred even when the entire C-terminal domain was truncated. |
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