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GrainGenes Reference Report: TPJ-33-373

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Reference	TPJ-33-373
Title	The DNA-binding activity of an AP2 transcriptional activator HvCBF2 involved in regulation of low-temperature responsive genes in barley is modulated by temperature
Journal	Plant Journal
Year	2003
Volume	33
Pages	373-383
Author	Xue GP
Abstract	Summary: An HvCBF2 cDNA was isolated from barley leaves. It encoded a protein containing an AP2 DNA-binding domain homologous to C-repeat (CRT)/dehydration-responsive element (DRE) binding factors (CBF/DREB1). In contrast to the previously reported cold-inducible CBF/DREB1 genes, HvCBF2 was expressed in barley leaves under non-stress conditions. Only a transient increase in the HvCBF2 transcript level was observed during cold treatment. Transactivation analysis showed that HvCBF2 was a transcriptional activator, capable of activating expression of a reporter gene driven by a low-temperature and drought-responsive HVA1s promoter in barley leaves. The activity of HvCBF2 as a transcriptional activator was upregulated by low temperature. DNA-binding analysis revealed that HvCBF2 did not bind to the CRT/DRE motif at 30(degree)C. A low, but detectable, binding activity was observed at 25(degree)C and the binding activity gradually increased as the temperature decreased. The binding activity at 0(degree)C was the highest and more than 10 times higher than that at 25(degree)C. The activation and inactivation of HvCBF2 activity were reversible and were achieved in a cell-free system simply by temperature change. Analysis of the binding sequence showed that HvCBF2 bound to a (G/a)(T/c)CGAC core motif, where the lower-case letters are less efficient bases. These data suggest that HvCBF2 is a transcription factor interacting with the core CRT/DRE motif containing a preferred sequence of GTCGAC and its DNA-binding activity is regulated by temperature. This represents a new type of activation mechanism for transcriptional activators
External Databases	Pubmed: 12535350
Keyword	[ Hide all but 1 of 32 ] activation ap2 domain arabidopsis thaliana barley cdna cold acclimation crt/dre elements dna binding domain drought efficient element family freezing tolerance gene hva1 mechanism promoter protein regulation reporter reporter gene responsive gene sequence stress system temperature transcription transcription factor transcriptional activator transient water-deficit

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