STRUCTURE AND MOBILITY OF THE PUT3 DIMER

The solution structure and backbone dynamics of the transcriptional ac tivator PUT3 (31-100) has been characterized using NMR spectroscopy. P UT3 (31-100) contains three distinct domains: a cysteine zinc cluster, linker, and dimerization domain, The cysteine zinc cluster of PUT3 cl osely resembles the solution structure of GAL4, while the dimerization domain forms a long coiled-coil similar to that observed in the cryst al structures of GAL4 and PPR1. However, the residues at the N-termina l end of the coiled-coil behave very differently in each of these prot eins. A comparison of the structural elements within this region provi des a model for the DNA binding specificity of these proteins. Further more, we have characterized the dynamics of PUT3 to find that the zinc cluster and dimerization domains have very diverse dynamics in soluti on. The dimerization domain behaves as a large protein, while the peri pheral cysteine zinc clusters have dynamic properties similar to small proteins.