Threshold-dependent transcriptional discrimination underlies stem cell homeostasis.
Transcriptional mechanisms that underlie the dose-dependent regulation of gene expression in animal development have been studied extensively. However, the mechanisms of dose-dependent transcriptional regulation in plant development have not been understood. In Arabidopsis shoot apical meristems, WUSCHEL (WUS), a stem cell-promoting transcription factor, accumulates at a higher level in the rib meristem and at a lower level in the central zone where it activates its own negative regulator, CLAVATA3 (CLV3). How WUS regulates CLV3 levels has not been understood. Here we show that WUS binds a group of cis-elements, cis- regulatory module, in the CLV3-regulatory region, with different affinities and conformations, consisting of monomers at lower concentration and as dimers at a higher level. By deleting cis elements, manipulating the WUS-binding affinity and the homodimerization threshold of cis elements, and manipulating WUS levels, we show that the same cis elements mediate both the activation and repression of CLV3 at lower and higher WUS levels, respectively. The concentration-dependent transcriptional discrimination provides a mechanistic framework to explain the regulation of CLV3 levels that is critical for stem cell homeostasis.
Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, Center for Plant Cell Biology, University of California, Riverside, CA 92521.
Mariano
M
Perales
Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, Center for Plant Cell Biology, University of California, Riverside, CA 92521.
Kevin
K
Rodriguez
Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, Center for Plant Cell Biology, University of California, Riverside, CA 92521.
Stephen
S
Snipes
Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, Center for Plant Cell Biology, University of California, Riverside, CA 92521.
Ram Kishor
RK
Yadav
Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, Center for Plant Cell Biology, University of California, Riverside, CA 92521.
Mercedes
M
Diaz-Mendoza
Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, Center for Plant Cell Biology, University of California, Riverside, CA 92521 venug@ucr.edu.
G Venugopala
GV
Reddy
D017360:Arabidopsis / Q000235:genetics; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites; D018506:Gene Expression Regulation, Plant; D018398:Homeodomain Proteins / Q000737:chemistry / Q000378:metabolism; D006706:Homeostasis; D009154:Mutation; D018520:Plant Shoots; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D055503:Protein Multimerization; D038621:Regulatory Sequences, Ribonucleic Acid; D013234:Stem Cells / Q000378:metabolism*; D014158:Transcription, Genetic
C118167:AT2G27250 protein, Arabidopsis; D029681:Arabidopsis Proteins; D018398:Homeodomain Proteins; D038621:Regulatory Sequences, Ribonucleic Acid; C116421:WUSCHEL protein, Arabidopsis
CLAVATA3; WUSCHEL; cis-regulatory module; gene regulation; shoot apical meristem
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