Eintrag weiter verarbeiten
The SPA1‐like proteins SPA3 and SPA4 repress photomorphogenesis in the light
Gespeichert in:
| Zeitschriftentitel: | The Plant Journal |
|---|---|
| Personen und Körperschaften: | , |
| In: | The Plant Journal, 35, 2003, 3, S. 373-385 |
| Format: | E-Article |
| Sprache: | Englisch |
| veröffentlicht: |
Wiley
|
| Schlagwörter: |
| Zusammenfassung: | <jats:title>Summary</jats:title><jats:p> <jats:styled-content>S</jats:styled-content>uppressor of <jats:italic><jats:styled-content>p</jats:styled-content>hy<jats:styled-content>A</jats:styled-content>‐105</jats:italic> (SPA1) is a phytochrome A‐specific signaling intermediate that acts as a light‐dependent repressor of photomorphogenesis in <jats:italic>Arabidopsis</jats:italic> seedlings. <jats:italic>SPA1</jats:italic> is part of a small gene family comprising three genes: <jats:italic><jats:styled-content>SPA</jats:styled-content>1‐related <jats:styled-content>2</jats:styled-content></jats:italic> (<jats:italic>SPA2</jats:italic>), <jats:italic><jats:styled-content>SPA</jats:styled-content>1‐related <jats:styled-content>3</jats:styled-content></jats:italic> (<jats:italic>SPA3</jats:italic>), and <jats:italic><jats:styled-content>SPA</jats:styled-content>1‐related <jats:styled-content>4</jats:styled-content></jats:italic> (<jats:italic>SPA4</jats:italic>). Here, we investigate the functions of <jats:italic>SPA3</jats:italic> and <jats:italic>SPA4</jats:italic>, two very closely related genes coding for proteins with 74% identical amino acids. Seedlings with mutations in <jats:italic>SPA3</jats:italic> or <jats:italic>SPA4</jats:italic> exhibit enhanced photomorphogenesis in the light, but show no phenotype in darkness. While there are small differences between the effects of <jats:italic>spa3</jats:italic> and <jats:italic>spa4</jats:italic> mutations, it is apparent that <jats:italic>SPA3</jats:italic> and <jats:italic>SPA4</jats:italic> function to inhibit light responses in continuous far‐red, red, and blue light. Phytochrome A is necessary for all aspects of the <jats:italic>spa4</jats:italic> mutant phenotype, suggesting that <jats:italic>SPA4</jats:italic>, like <jats:italic>SPA1</jats:italic>, acts specifically in phytochrome A signaling. Enhanced photoresponsiveness of <jats:italic>spa3</jats:italic> mutants is also fully dependent on phytochrome A in far‐red and blue light, but not in red light. Hence, <jats:italic>SPA3</jats:italic> function in red light may be dependent on other phytochromes in addition to phytochrome A. Using yeast two‐hybrid and <jats:italic>in vitro</jats:italic> interaction assays, we further show that SPA3 as well as SPA4 can physically interact with the constitutive repressor of light signaling COP1. Deletion analyses suggest that SPA3 and SPA4, like SPA1, bind to the coiled‐coil domain of COP1. Taken together, our results have identified two new loci coding for negative regulators that may be involved in fine tuning of light responses by interacting with COP1.</jats:p> |
|---|---|
| Umfang: | 373-385 |
| ISSN: |
0960-7412
1365-313X |
| DOI: | 10.1046/j.1365-313x.2003.01813.x |