NMR Backbone Dynamics of VEK-30 Bound to the Human Plasminogen Kringle 2 Domain

• Published in: Biophysical journal 2010-07, Vol.99 (1), p.302-312
• Main Authors: Wang, Min, Prorok, Mary, Castellino, Francis J.
• Format: Article
• Language: English
• Subjects: Antigens, Bacterial - chemistry; Backbone; Bacterial Outer Membrane Proteins - chemistry; Binding; Carrier Proteins - chemistry; Correlation analysis; Dynamic tests; Dynamics; Human; Humans; Kringles; Ligands; Mathematical models; Measurement; Models, Molecular; Movement; NMR; Nuclear magnetic resonance; Nuclear Magnetic Resonance, Biomolecular; Peptide Fragments - metabolism; Peptides; Plasminogen - chemistry; Plasminogen - metabolism; Protein; Protein Binding; Proteins; Streptococcus; Streptococcus infections
• ISSN: 0006-3495; 1542-0086; 1542-0086
• DOI: 10.1016/j.bpj.2010.04.019

To gain insights into the mechanisms for the tight and highly specific interaction of the kringle 2 domain of human plasminogen (K2 Pg) with a 30-residue internal peptide (VEK-30) from a group A streptococcal M-like protein, the dynamic properties of free and bound K2 Pg and VEK-30 were investigated using backbone amide 15N-NMR relaxation measurements. Dynamic parameters, namely the generalized order parameter, S 2, the local correlation time, τ e, and the conformational exchange contribution, R ex, were obtained for this complex by Lipari-Szabo model-free analysis. The results show that VEK-30 displays distinctly different dynamic behavior as a consequence of binding to K2 Pg, manifest by decreased backbone flexibility, particularly at the binding region of the peptide. In contrast, the backbone dynamics parameters of K2 Pg displayed similar patterns in the free and bound forms, but, nonetheless, showed interesting differences. Based on our previous structure-function studies of this interaction, we also made comparisons of the VEK-30/K2 Pg dynamics results from different kringle modules complexed with small lysine analogs. The differences in dynamics observed for kringles with different ligands provide what we believe to be new insights into the interactions responsible for protein-ligand recognition and a better understanding of the differences in binding affinity and binding specificity of kringle domains with various ligands.