Jacob, Yannick , Michaels, Scott D. .
ATXR5 and ATXR6 are replication-dependent chromatin modifiers affecting flowering time in Arabidopsis thaliana.
Histone methylation has been shown to play a key role in regulating the transition from vegetative to reproductive growth in Arabidopsis thaliana. SET domain proteins use their lysine methyltransferase activity to modify specific histone residues, which in turn dictates the transcriptional state of genes. Here we describe the identification of two SET domain proteins affecting flowering time in A. thaliana. A screen for suppressors of the late-flowering luminidependens (ld) mutation has revealed an early-flowering dominant mutation (lds1a). ld mutants are late flowering due to elevated expression of the floral inhibitor FLC. In early-flowering lds1a mutants, however, FLC levels were unaffected. Instead, expression of the floral promoters SOC1, FT and TSF was increased. A T-DNA insertion in lds1a has been identified ~2.5 kbp upstream of the start codon of the gene ATXR6. Constitutive expression of ATXR6 resulted in early flowering. Flowering time was unaffected by a reduction-of-function allele of ATXR6. Similarly, a mutation in the closely related gene ATXR5 had no impact on flowering time. However, constitutive expression of ATXR5 also accelerated flowering. ATXR6 and ATXR5 are SET domain proteins that have recently been shown to be cell-cycle regulated, being expressed at the G1-S transition, and to interact with the replication factor PCNA. In conjunction with our results, this suggests that ATXR6 and ATXR5 function as replication-coupled chromatin modifiers.
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1 - Indiana University, Biology, 1001 East Third Street, Bloomington, Indiana, 47405, USA
SET domain proteins
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM