Isolation and characterization of the wheat prolyl isomerase FK506-binding protein (FKBP) 73 promoter

The wheat FK506-binding protein (FKBP) 73 is a member of the peptidyl prolyl cis-trans isomerase gene family, which catalyses the interconversion between the cis and trans forms of the peptide bond preceding proline residues in proteins. A 3.5 kb sequence 5' upstream of the ATG codon of the wheat FKBP73 was isolated from a wheat genomic library, and characterized by deletion analysis and transient expression in wheat embryos. The 1517 bp fragment is referred to as the full promoter due to the maximal activity of the fused luciferase reporter gene. Sequence analysis revealed the presence of three abscisic acid (ABA)-responsive elements (ABREs) proximal to coupling elements (CE1-like), a putative lectin box, two putative binding sites for the myb transcription factor and a 36 bp fragment which exhibits 100% identity to the pSau3A9 clone located in the centromeric region of wheat chromosomes. In a transient expression assay the promoter preserved the tissue specificity described in vivo, namely it is expressed only in germinating embryos and young shoots. The promoter was induced 1.9-fold by ABA, the minimal promoter was designated at -221 and the TATA box located at -137. The inducibility by ABA and the expression during germination may indicate that FKBP73 belongs to the group of genes induced by ABA upon germination.