Studies on the expression of the wheat prolyl isomerase FKBP73 during plant development

Prolyl isomerases are ubiquitous proteins which accelerate the slow steps of protein folding by isomerisation of peptide bonds in which proline participates. We have isolated and characterised a wheat prolyl isomerase belonging to the FK506 binding protein family (FKBP) named wFKBP73. By using polyclonal antibodies raised against the recombinant wheat FKBP, its expression in wheat organs, during seed imbibition and caryopsis maturation was studied. The highest level of the wFKBP73 expression was found in imbibed embryos and 2 day old seedlings, whereas the protein could not be detected in mature green leaves. When young leaves and roots were dissected into segments, the highest expression was associated with the meristematic region. The wFKBP73 accumulated during seed maturation and was present in dry seeds. Its presence in dry seeds may suggest its importance in assisting correct folding of newly synthesized proteins and maintaining the native structure of certain macromolecules. The wFKBP73 was determined to be a stable protein with a half life of 41 h. The polyclonal antibodies raised against the recombinant protein detected cross reacting proteins in barley, corn, rice, and pea suggesting that the FKBP73 is a conserved protein in plants. The wFKBP locus Xtavl926(Fkbp) was mapped on the short arm of the wheat group seven chromosome. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.