NUCLEAR-MAGNETIC-RESONANCE SOLUTION STRUCTURE OF THE HUMAN HSP40 (HDJ-1) J-DOMAIN

The J-domain is a highly conserved domain found in all members of the DnaJ family of molecular chaperones. The three-dimensional structure o f a recombinant, uniformly N-15-labeled 77-residue polypeptide contain ing the complete J-domain from human Hsp40 (HDJ-1) has been determined by nuclear magnetic resonance (NMR) spectroscopy in solution. On the basis of 876 upper distance constraints derived from nuclear Overhause r effects (NOE) and 173 dihedral angle constraints, a group of 20 conf ormers representing the solution structure of the HDJ-1 J-domain was c omputed with the program DIANA and energy-minimized with the program O PAL. The average of the pairwise root-mean-square deviations of the in dividual NMR conformers relative to the mean coordinates for the backb one atoms N, C-alpha and C' of residues 4 to 54 and 4 to 66 is 0.88 an d 0.99 Angstrom respectively. The molecular architecture includes four helices composed of residues 5 to 9, 15 to 28, 40 to 54 and 60 to 66. A turn composed of residues 10 to 14 links helices I and II, and a lo op composed of residues 29 to 39 containing a highly conserved tripept ide HPD (residues 31 to 33) connects the antiparallel helices II and I II. The tertiary fold formed by helix I-turn-helix II-loop-helix III f orms a closed structural core; the less defined helix IV stands away f rom the core of the domain. The side-chains of the tripeptide HPD exte nd out from the core of the structure in the opposite direction from h elix IV. The structure supports the hypothesis that the highly conserv ed tripeptide could play a key role in the interaction of Hsp40 with t he molecular chaperone, Hsp70. (C) 1996 Academic Press Limited