Characterization of a strong dominant phytochrome A mutation unique to phytochrome a signal propagation

Fry, Rebecca C., Habashi, Jessica, Okamoto, Haruko and Deng, Xing Wang (2002) Characterization of a strong dominant phytochrome A mutation unique to phytochrome a signal propagation. Plant Physiology, 130 (1), 457-465. (10.?1104/?pp.?005264).

Abstract

Here, we report the isolation and characterization of a strong dominant-negative phytochrome A(phyA) mutation (phyA-300D) in Arabidopsis. This mutation carries a single amino acid substitution at residue 631, from valine to methionine (V631M), in the core region within the C-terminal half of PHYA. This PHYA core region contains two protein-interactive motifs, PAS1 and PAS2. Val-631 is located within the PAS1 motif. The phyA-V631M mutant protein is photochemically active and accumulates to a level similar to wild type in dark-grown seedlings. Overexpression of PHYA-V631M in a wild-type background results in a dominant-negative interference with endogenous wild-type phyA, whereas PHYA-V631M in aphyA null mutant background is inactive. To investigate the specificity of this mutation within the phytochrome family, the corresponding amino acid substitution (V664M) was created in the PHYTOCHROME B (PHYB) polypeptide. We found that the phyB-V664M mutant protein is physiologically active in phyB mutant and causes no interfering effect in a wild-type background. Together, our results reveal a unique feature in phyA signal propagation through the C-terminal core region

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