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Human macrophage inflammatory protein 3alpha: protein and peptide nuclear magnetic resonance solution structures, dimerization, dynamics, and anti-infective properties.

ABSTRACT: Human macrophage inflammatory protein 3alpha (MIP-3alpha), also known as CCL20, is a 70-amino-acid chemokine which exclusively binds to chemokine receptor 6. In addition, the protein also has direct antimicrobial, antifungal, and antiviral activities. The solution structure of MIP-3alpha was solved by the use of two-dimensional homonuclear proton nuclear magnetic resonance (NMR). The structure reveals the characteristic chemokine fold, with three antiparallel beta strands followed by a C-terminal alpha helix. In contrast to the crystal structures of MIP-3alpha, the solution structure was found to be monomeric. Another difference between the NMR and crystal structures lies in the angle of the alpha helix with respect to the beta strands, which measure 69 and approximately 56.5 degrees in the two structures, respectively. NMR diffusion and pH titration studies revealed a distinct tendency for MIP-3alpha to form dimers at neutral pH and monomers at lower pH, dependent on the protonation state of His40. Molecular dynamics simulations of both the monomeric and the dimeric forms of MIP-3alpha supported the notion that the chemokine undergoes a change in helix angle upon dimerization and also highlighted the important hydrophobic and hydrogen bonding contacts made by His40 in the dimer interface. Moreover, a constrained N terminus and a smaller binding groove were observed in dimeric MIP-3alpha simulations, which could explain why monomeric MIP-3alpha may be more adept at receptor binding and activation. The solution structure of a synthetic peptide consisting of the last 20 residues of MIP-3alpha displayed a highly amphipathic alpha helix, reminiscent of various antimicrobial peptides. Antimicrobial assays with this peptide revealed strong and moderate bactericidal activities against Escherichia coli and Staphylococcus aureus, respectively. This confirms that the C-terminal alpha-helical region of MIP-3alpha plays a significant part in its broad anti-infective activity.

SUBMITTER: Chan DI

PROVIDER: S-EPMC2258517 | biostudies-literature | 2008 Mar

REPOSITORIES: biostudies-literature

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Human macrophage inflammatory protein 3alpha: protein and peptide nuclear magnetic resonance solution structures, dimerization, dynamics, and anti-infective properties.

Chan David I DI Hunter Howard N HN Tack Brian F BF Vogel Hans J HJ

Antimicrobial agents and chemotherapy 20071217 3

Human macrophage inflammatory protein 3alpha (MIP-3alpha), also known as CCL20, is a 70-amino-acid chemokine which exclusively binds to chemokine receptor 6. In addition, the protein also has direct antimicrobial, antifungal, and antiviral activities. The solution structure of MIP-3alpha was solved by the use of two-dimensional homonuclear proton nuclear magnetic resonance (NMR). The structure reveals the characteristic chemokine fold, with three antiparallel beta strands followed by a C-termina ...[more]

PMID: 18086840

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Project description:Protein kinases are ubiquitous enzymes with critical roles in cellular processes and pathology. As a result, researchers have studied their activity and regulatory mechanisms extensively. Thousands of X-ray structures give snapshots of the architectures of protein kinases in various states of activation and ligand binding. However, the extent of and manner by which protein motions and conformational dynamics underlie the function and regulation of these important enzymes is not well understood. Nuclear magnetic resonance (NMR) methods provide complementary information about protein conformation and dynamics in solution. However, until recently, the large size of these enzymes prevented researchers from using these methods with kinases. Developments in transverse relaxation-optimized spectroscopy (TROSY)-based techniques and more efficient isotope labeling strategies are now allowing researchers to carry out NMR studies on full-length protein kinases. In this Account, we describe recent insights into the role of dynamics in protein kinase regulation and catalysis that have been gained from NMR measurements of chemical shift changes and line broadening, residual dipolar couplings, and relaxation. These findings show strong associations between protein motion and events that control kinase activity. Dynamic and conformational changes occurring at ligand binding sites and other regulatory domains of these proteins propagate to conserved kinase core regions that mediate catalytic function. NMR measurements of slow time scale (microsecond to millisecond) motions also reveal that kinases carry out global exchange processes that synchronize multiple residues and allosteric interconversion between conformational states. Activating covalent modifications or ligand binding to form the Michaelis complex can induce these global processes. Inhibitors can also exploit the exchange properties of kinases by using conformational selection to form dynamically quenched states. These investigations have revealed that kinases are highly dynamic enzymes, whose regulation by interdomain interactions, ligand binding, and covalent modifications involve changes in motion and conformational equilibrium in a manner that can be correlated with function. Thus, NMR provides a unique window into the role of protein dynamics in kinase regulation and catalysis with important implications for drug design.

Dataset Information

Human macrophage inflammatory protein 3alpha: protein and peptide nuclear magnetic resonance solution structures, dimerization, dynamics, and anti-infective properties.

Publications

Human macrophage inflammatory protein 3alpha: protein and peptide nuclear magnetic resonance solution structures, dimerization, dynamics, and anti-infective properties.

Similar Datasets

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