Plant Physiol, September 2002, Vol. 130, pp. 457-465
Characterization of a Strong Dominant phytochrome A
Mutation Unique to Phytochrome A Signal
Propagation1
Rebecca C.
Fry,2
Jessica
Habashi,
Haruko
Okamoto,3 and
Xing Wang
Deng*
Department of Molecular, Cellular, and Developmental Biology, Yale
University, New Haven, Connecticut 06511-8104
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 a
phyA 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.
1
This work was supported by the National
Institutes of Health (grant no. GM47850 to X.W.D.). X.W.D. was a
National Science Foundation Presidential Faculty Fellow, and J.H. is a
National Institutes of Health predoctoral trainee.
2
Present address: Massachusetts Institute of Technology,
77 Massachusetts Avenue, Cambridge, MA 02139.
3
Present address: The Department of Plant Sciences,
University of Oxford, Oxford OX1 3RB, UK.
*
Corresponding author; e-mail xingwang.deng{at}yale.edu; fax
203-432-5726.
© 2002 American Society of Plant Physiologists
