Understanding Protein Function - The Disparity Between Bioinformatics and Molecular Methods

Substitutions of Conserved Residues in the C-terminal Region of DnaC Cause Thermolability in Helicase Loading

“…3). BSA served as coli DnaC with 29 DnaC homologues reveals conserved residues shown as uppercase letters relative to its secondary structure (hatched boxes, ␣ helix; filled boxes, ␤ strand) derived from the A. aeolicus DnaC x-ray crystallographic structure and from a secondary structure prediction method (PHDsec) (10,12,14). The numbers at the right are the coordinates for E. coli DnaC protein.…”

“…In those AAAϩ motifs that have been examined, amino acid substitutions cause impaired function, indicating that these conserved residues are indispensable (10 -13). Other residues near the C terminus (residue 245) are very highly conserved (14). This portion of DnaC is absent in the x-ray crystallographic structure of Aquifex aeolicus DnaC bound to ADP, but part of this region ending with the sensor 2 arginine forms a loop in the x-ray structure of this protein bound to ADP-BeF 3 , an ATP mimetic (12).…”