DNA binding specificity of ATAF2, a NAC domain transcription factor targeted for degradation by Tobacco mosaic virus
DNA binding specificity of ATAF2, a NAC domain transcription factor targeted for degradation by Tobacco mosaic virus
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Date
2012-08-31
Authors
Wang, Xiao
Culver, James N
Advisor
Citation
Wang, X., Culver, J.N. DNA binding specificity of ATAF2, a NAC domain transcription factor targeted for degradation by Tobacco mosaic virus. BMC Plant Biol 12, 157 (2012).
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Abstract
Background: Control of the host transcriptome represents a key battleground in the interaction of plants and
pathogens. Specifically, plants have evolved complex defense systems that induce profound transcriptional changes
in response to pathogen attack while pathogens have evolved mechanisms to subvert or disable these defenses.
Several NAC transcription factors such as ATAF2 have been linked to plant defense responses, including those
targeting viruses. The replication protein of Tobacco mosaic virus (TMV) has been shown to interact with and target
the degradation of ATAF2. These findings suggest that the transcriptional targets of ATAF2 are involved in defense
against TMV.
Results: To detect potential ATAF2 transcriptional targets, a genomic pull-down assay was utilized to identify
ATAF2 promoter binding sequences. Subsequent mobility shift and DNA footprinting assays identified a 30-bp
ATAF2 binding sequence. An in vivo GUS reporter system confirmed the function of the identified 30-bp binding
sequence as an ATAF2 specific transcriptional activator in planta. Gel filtration studies of purified ATAF2 protein and
mutagenesis studies of the 30-bp binding sequence indicate ATAF2 functions as a dimer. Computational analysis of
interacting promoter sequences identified a corresponding 25-bp A/T-rich consensus sequence with repeating [GC]
AAA motifs. Upon ATAF2 induction real-time qRT-PCR studies confirmed the accumulation of select gene transcripts
whose promoters contain this consensus sequence.
Conclusion: We report the identification of a cis-regulatory binding sequence for ATAF2. Different from other
known NAC protein binding sequences, the A/T-rich ATAF2 binding motif represents a novel binding sequence for
NAC family proteins. Combined this information represents a unique tool for the identification of ATAF2 target
genes.