Abstract
Ssu72 helps regulate transcription and co-transcriptional mRNA processing by dephosphorylating serine residues at the 5th position in the heptad repeats of the C-terminal domain of RNA polymerase II. Here we use multidimensional, multinuclear NMR experiments to assign the backbone and side-chain resonances of the 23 kDa Ssu72 from Drosophila melanogaster in the phosphate-bound state, and use NMR titrations to examine the phosphate-binding properties of three active site mutants.