TABLE 1

NMR structure statistics for the CUS3 and Sf6 I-domains

ParameterValue for the I-domain of:
CUS-3Sf6
Total no. of NMR restraints2,1141,412
Total no. of NOE distance restraints1,8881,150
    Long range (|i – j| > 4)504397
    Medium range (|ij| ≤ 4)24236
    Sequential (|ij| = 1)558348
    Intraresidue584369
Total no. of dihedral restraints202233
    φ/ψ156183
    χ14650
No. of H-bond restraints (2/bond)4858
RMSD from ideal geometry
    Bonds (Å)0.0039 ± 0.000140.0046 ± 0.00028
    Angles (°)0.57 ± 0.030.61 ± 0.04
    Improper angles (°)1.71 ± 0.121.90 ± 0.19
RMSD from experimental restraintsa
    NOE distance (Å)0.0207 ± 0.001190.0643 ± 0.01413
    Dihedral (°)0.807 ± 0.14600.678 ± 0.2531
RMSD from mean structure (Å)
    Entire structure backbone2.15 ± 0.403.58 ± 0.87
    Entire structure heavy atoms2.57 ± 0.384.23 ± 0.84
    Ordered region, backboneb0.92 ± 0.190.88 ± 0.21
    Ordered region heavy atomsb1.53 ± 0.231.43 ± 0.20
    β-barrel, backbonec0.66 ± 0.180.66 ± 0.16
    β-barrel, heavy atomsc1.16 ± 0.241.18 ± 0.22
Ramachandran plot-Procheck (%)d
    Most favored84.773.8
    Additionally allowed12.925.9
    Generously allowed1.90.3
    Disallowed0.60.0
PSVS Quality Z-scoresd
    Procheck (φ/ψ)d–2.60–3.86
    Molprobity clash–5.97–3.8
  • a Structures had no NOE violations of >0.5 Å or dihedral violations of >5°.

  • b Backbone atoms were Cα, C′, N, and O. Ordered regions based on 15N relaxation data (Fig. 5) were the following: for CUS-3, residues 228 to 238, 249 to 275, 286 to 308, and 319 to 336 (79 residues); for Sf6, residues 226 to 240, 243 to 274, 292 to 315, and 334 to 341 (79 residues).

  • c Residues that comprise the conserved six-stranded β-barrel motif are as follows: for CUS-3, residues 226 to 238, 245 to 253, 266 to 271, 292 to 296, 308 to 313, and 335 to 341 (35 residues); for Sf6, residues 226 to 238, 245 to 253, 266 to 271, 292 to 296, 308 to 313, and 335 to 341 (46 residues).

  • d Calculated using the Protein Structure Validation Suite (PSVS)(42).