Cold shock domain of the human Y-box protein YB-1. Backbone dynamics and equilibrium between the native state and a partially unfolded state.
The three-dimensional structure of the central cold shock domain (CSD) of the human Y-box protein (YB-1 CSD) is virtually identical to those available for the bacterial cold shock proteins (Csp's). We have further characterized YB-1 CSD by studying its dynamics by nuclear magnetic resonance. The observed structural similarity is reflected in the backbone dynamics, which for YB-1 CSD is very similar to that of the Escherichia coli protein CspA. The rotational correlation time of YB-1 CSD shows that it is a monomer. This indicates that the dimerization observed for the YB-1 protein is not caused by its CSD, but involves other parts of this protein. The YB-1 CSD is only marginally stable as are the mesophilic bacterial Csp's. In contrast to the rapid two-state folding of the bacterial Csp's, the formation of the native form of YB-1 CSD is slow and at least a three-state process. The NMR experiments revealed the presence of a second state of YB-1 CSD in equilibrium with the native form. The exchange rates from and to the folded state are in the order of 0.2 and 0.5 s(-1), respectively. Relaxation experiments indicated that the second state is a highly flexible, partly structured molecule.
NSRIM Centre, Faculty of Science, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands.
Cathelijne P A M
CP
Kloks
Marco
M
Tessari
Geerten W
GW
Vuister
Cornelis W
CW
Hilbers
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry; D003080:Cold Temperature; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D041961:Deuterium Exchange Measurement; D006801:Humans; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D009687:Nuclear Proteins; D011485:Protein Binding; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D040681:Structural Homology, Protein; D013816:Thermodynamics; D051840:Y-Box-Binding Protein 1
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D051840:Y-Box-Binding Protein 1; C070856:YBX1 protein, human; C062260:cold shock protein CS7.4, Bacteria