Determination of the Nuclear Magnetic Resonance Structure of the DNA-binding Domain of the P22 c2 Repressor (1 to 76) in Solution and Comparison with the DNA-binding Domain of the 434 Repressor

摘要: Abstract The solution structure of the N-terminal DNA-binding domain P22 c2 repressor (residues 1 to 76) was determined by nuclear magnetic resonance (NMR) spectroscopy. determination based on nearly complete sequence-specific assignments for H, 13 C and 15 N, tables chemical shifts all three nuclei are included here. A group 20 conformers calculated from NMR constraints using program DIANA, energy-minimized an implementation AMBER force field in OPAL. core protein formed residues 5 68 is structurally well defined, with average 0·7 root-mean-square deviations backbone atoms individual relative mean coordinates. tetrapeptide segment C-terminal octapeptide flexibly disordered. molecular architecture includes five α-helical segments 6 17, 21 28, 32 39, 47 57 61 65. length orientation these helices closely similar arrangement corresponding regular secondary structures 434 repressor, sole exception fourth helix, which one turn longer at its amino-terminal end than helix repressor. This extension implies that DNA binding mode must be somewhat different observed Exact superposition two domains best fit polypeptide onto crystal repressor-DNA complex would result a model could not accommodate because steric overlap.