Phosphorylation of nuclear proteins directs binding to salicylic acid-responsive elements

Plant J. 1997 Jun;11(6):1315-24. doi: 10.1046/j.1365-313x.1997.11061315.x.

Abstract

The cis-located DNA sequence as-1 (Activation Sequence-1) from CaMV 35S promoter has been previously identified as an element that can confer inducibility by salicylic acid (SA) with immediate early kinetics. This sequence specifically binds to ASF-1 (Activation Sequence Factor-1), previously characterized in tobacco nuclear extracts. To assess whether modulation of ASF-1 binding activity can explain the activation of the as-1 sequence observed in vivo, we performed electrophoretic mobility shift assays using nuclear extracts from SA-treated and water-treated tobacco plants. Our results indicate that treatment of plants with SA increases ASF-1 binding to as-1 and to ocs, an as-1-like element from the Agrobacterium octopine synthase gene. In contrast, SA treatment has no effect on the binding of GT-1 factor to its target light-inducible box II element. Furthermore, treatment of nuclear extracts from SA-treated plants with alkaline phosphatase decreases ASF-1 binding to the as-1 element. This can be reversed by pretreatment with 10 mM NaF. Accordingly, pretreatment of nuclear extracts from control water-treated plants with ATP produces an increase in ASF-1 binding activity similar to that observed with SA. This effect of ATP is reversed by treatment with alkaline phosphatase and prevented by quercetin, a casein kinase II inhibitor. These results support the hypothesis that a nuclear protein kinase is involved in the immediate early events of transcriptional activation triggered by SA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis Proteins*
  • Basic-Leucine Zipper Transcription Factors
  • Binding Sites
  • DNA, Plant / metabolism*
  • DNA-Binding Proteins / metabolism
  • Nuclear Proteins / metabolism*
  • Phosphorylation
  • Plant Proteins / metabolism
  • Plants, Toxic
  • Salicylates / metabolism*
  • Salicylic Acid
  • Tobacco / genetics
  • Transcription Factors / metabolism
  • Transcriptional Activation

Substances

  • ASF-2 protein, tobacco
  • Arabidopsis Proteins
  • Basic-Leucine Zipper Transcription Factors
  • DNA, Plant
  • DNA-Binding Proteins
  • Nuclear Proteins
  • Plant Proteins
  • Salicylates
  • TGA3 protein, Arabidopsis
  • Transcription Factors
  • Salicylic Acid