Submitted to: International Congress of Plant Molecular Biology
Publication Type: Abstract only
Publication Acceptance Date: 6/25/2003
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: The Arabidopsis thaliana genome encodes 17 members of the Hsp70 family, and 90 members of the Hsp70-activating J-domain protein family. The only known role for J-domain proteins is as a component of the Hsp70 chaperone machine. Some specificity in the interactions between species of Hsp70 and their J-domain cohorts is conveyed by subcellular compartmentation. Other factors that contribute to specificity have not yet been defined. Family 4 of the A. thaliana J-domain proteins contains only atDjC6 and atDjC37. Both of these proteins have nucleocytoplasmic localization. In order to test cohort specificity, we have analyzed interactions between atDjC6 and atDjC37, and the Hsp70 proteins that have a predicted nucleocytoplasmic localization, using the BacterioMatch Two-Hybrid system. Both of the J-domain proteins were cloned into the pBT vector, and AtHsp70-1, -2, -3, -4, -5, and -14 were cloned into pTRG. In this artificial genetic system, interacting proteins yield an active beta-galactosidase. After co-transformation of Escherichia coli with the various permutations of potential interacting proteins, cells were selected, and enzyme activity measured to quantify the extent of interaction. Each of the J-domain proteins interacted with all species of Hsp70, but there was divergence in the specificity of interaction (atDjC6:AtHsp70-1 > 2 = 14 = 5 = 4 > 3; atDjC37:AtHsp70-4 > 1 > 3 = 2 = 5 > 14). Recombinant atDjC6 and atDjC37 were prepared in Escherichia coli, and tested for their ability to stimulate the ATPase activity of DnaK and recombinant AtHsp70-1.