RRC ID 6291
Author Wang H, Zhu Y, Fujioka S, Asami T, Li J, Li J.
Title Regulation of Arabidopsis brassinosteroid signaling by atypical basic helix-loop-helix proteins.
Journal Plant Cell
Abstract Basic helix-loop-helix (bHLH) proteins are highly conserved transcription factors critical for cell proliferation and differentiation. Recent studies have implicated bHLH proteins in many plant signaling processes, including brassinosteroid (BR) signaling. Here, we report identification of two families of atypical bHLH proteins capable of modulating BR signaling. We found that activation-tagged bri1 suppressor 1-Dominant (atbs1-D), previously identified as a dominant suppressor of a weak BR receptor mutant bri1-301, was caused by overexpression of a 93-amino acid atypical bHLH protein lacking amino acids critical for DNA binding. Interestingly, atbs1-D only suppresses weak BR mutants, while overexpression of a truncated ATBS1 lacking the basic motif also rescues bri1-301, suggesting that ATBS1 likely stimulates BR signaling by sequestering negative BR signaling components. A yeast two-hybrid screen using ATBS1 as bait discovered four ATBS1-Interacting Factors (AIFs) that are members of another atypical bHLH protein subfamily. AIF1 exhibits an overlapping expression pattern with ATBS1 and its homologs and interacts with ATBS1 in vitro and in vivo. AIF1 overexpression nullifies the suppressive effect of atbs1-D on bri1-301 and results in dwarf transgenic plants resembling BR mutants. By contrast, silencing of AIF1 partially suppressed the bri1-301 phenotype. Our results suggested that plants use these atypical bHLH proteins to regulate BR signaling.
Volume 21(12)
Pages 3781-91
Published 2009-12-1
DOI 10.1105/tpc.109.072504
PII tpc.109.072504
PMID 20023194
PMC PMC2814491
MeSH Amino Acid Sequence Arabidopsis / genetics* Arabidopsis / metabolism Arabidopsis Proteins / genetics Arabidopsis Proteins / metabolism* Basic Helix-Loop-Helix Transcription Factors / genetics Basic Helix-Loop-Helix Transcription Factors / metabolism* Gene Expression Regulation, Plant Gene Silencing Molecular Sequence Data Plant Growth Regulators / metabolism* Plants, Genetically Modified / genetics Plants, Genetically Modified / metabolism RNA, Plant / genetics Sequence Alignment Signal Transduction* Steroids / metabolism
IF 9.618
Times Cited 111
Arabidopsis / Cultured plant cells, genes pda