MOLECULAR-CLONING OF A SMALL DNA-BINDING PROTEIN WITH SPECIFICITY FORA TISSUE-SPECIFIC NEGATIVE ELEMENT WITHIN THE RPS1 PROMOTER

A cDNA encoding a specific binding activity for the tissue-specific ne gative cis-element S1F binding site of spinach rps1 was isolated from a spinach cDNA expression library, This cDNA of 0.7 kb encodes an unus ual small peptide of only 70 amino acids, with a basic domain which co ntains a nuclear localization signal and a putative DNA binding helix, This protein, named S1Fa, is highly conserved between dicotyledonous and monocotyledonous plants and may represent a novel class of DNA bin ding proteins, The corresponding mRNA is accumulated more in roots and in etiolated seedlings than in green leaves, This expression pattern is correlated with the tissue-specific function of the S1F binding sit e which represses the rps1 promoter preferentially in roots and in eti olated plants.