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have unusually high temperature factors. NMR studies have indicated significant
flexibility between residues 77 and 80. Molecular Dynamics (MD) simulations of the
central helix in explicit solvent have shown that the α-helical structure from residues 76
to 79 is lost after 700ps. Thus there is significant conformational flexibility in this region
which appears to be intrinsic.
All predictors gave the same, correct, result (Figure 7). The hinge in the middle of the
helix is a well documented one[110]. The FlexOracle energy plot has an unambiguous
minimum at the hinge location. There is also a minimum near the N-terminus, but since
the termini are usually flexible this is uninteresting. The success of TLSMD applied to
this particular structural model is quite unexpected, as the thermal factors in the PDB are
not crystallographically observed atomic displacements. Rather they are estimates of
mean displacement based on the RMSD differences of corresponding atomic positions in
a 25-member NMR ensemble. The structure shown in (a) is colored by HingeMaster
score, with red = lowest (most flexible) and blue = highest (least flexible). Residue 77 is
thus predicted to be the most likely hinge location, and is quite close to the HAG hinge.
Images such as this can be generated by users on MolMovDB.org and provide an
intuitive interpretation of HingeMaster results.
UDP-N-acetylglucosamine enolpyruvyltransferase (MurA) (apo form)[84]
Morph ID: f805267-29412 PDB ID: 1EJD
HAG hinges: 20,21,228,229
204