THE C-TERMINAL DOMAIN OF PEPTIDE DEFORMYLASE IS DISORDERED AND DISPENSABLE FOR ACTIVITY

Upon trypsinolysis, the 18 C-terminal residues of Escherichia coli pep tide deformylase were removed but the resulting form exhibited full ac tivity. Moreover, a mutant fms gene encoding the first 145 out of the 168 residues of the enzyme was able to complement a fms(Ts) strain and exhibited full activity. Upon progressive truncation up to residue 13 9, both activity and stability decreased up to complete inactivation, Mutagenesis of residues of the 138-145 region highlights the importanc e of Leu-141 and Phe-142. N-Terminal deletions were also carried out. Beyond two residues off, the enzyme showed a dramatic instability. Fin ally, NMR and thermostability studies of the full-length enzyme and co mparison to the 1-147 form strongly suggest that the dispensable resid ues are disordered in solution.