A Myb-related transcription factor is involved in the phytochrome regulation of an Arabidopsis Lhcb gene.
We have isolated the gene for a protein designated CCA1. This protein can bind to a region of the promoter of an Arabidopsis light-harvesting chlorophyll a/b protein gene, Lhcb1*3, which is necessary for its regulation by phytochrome. The CCA1 protein interacted with two imperfect repeats in the Lhcb1*3 promoter, AAA/cAATCT, a sequence that is conserved in Lhcb genes. A region near the N terminus of CCA1, which has some homology to the repeated sequence found in the DNA binding domain of Myb proteins, is required for binding to the Lhcb1*3 promoter. Lines of transgenic Arabidopsis plants expressing antisense RNA for CCA1 showed reduced phytochrome induction of the endogenous Lhcb1*3 gene, whereas expression of another phytochrome-regulated gene, rbcS-1A, which encodes the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase, was not affected. Thus, the CCA1 protein acts as a specific activator of Lhcb1*3 transcription in response to brief red illumination. The expression of CCA1 RNA was itself transiently increased when etiolated seedlings were transferred to light. We conclude that the CCA1 protein is a key element in the functioning of the phytochrome signal transduction pathway leading to increased transcription of this Lhcb gene in Arabidopsis.
Wang
Z Y
ZY
Department of Molecular, Cellular, and Developmental Biology, University of California, Los Angeles 90095-1606, USA.
Kenigsbuch
D
D
Sun
L
L
Harel
E
E
Ong
M S
MS
Tobin
E M
EM
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics*; D003001:Cloning, Molecular; D017124:Conserved Sequence; D018076:DNA, Complementary; D018506:Gene Expression Regulation, Plant; D045342:Light-Harvesting Protein Complexes; D008969:Molecular Sequence Data; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010834:Phytochrome / Q000502:physiology*; D010940:Plant Proteins; D011401:Promoter Regions, Genetic; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D020598:Proto-Oncogene Proteins c-myb; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000378:metabolism*
D029681:Arabidopsis Proteins; C490217:CAB1 protein, Arabidopsis; C114425:CCA1 protein, Arabidopsis; D002352:Carrier Proteins; D018076:DNA, Complementary; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D011518:Proto-Oncogene Proteins; D020598:Proto-Oncogene Proteins c-myb; D014157:Transcription Factors; D010834:Phytochrome