Thermodynamic Roles of Basic Amino Acids in Statherin Recognition of Hydroxyapatite
Abstract
Salivary statherin is a highly acidic, 43 amino acid residue protein that functions as an inhibitor of primary and secondary crystallization of the biomineral hydroxyapatite. The acidic domain at the N-terminus was previously shown to be important in the binding of statherin to hydroxyapatite surfaces. This acidic segment is followed by a basic segment whose role is unclear. In this study, the role of the basic amino acids in the hydroxyapatite adsorption thermodynamics has been determined using isothermal titration calorimetry and equilibrium adsorption isotherm analysis. Single point mutations of the basic side chains to alanine lowered the binding affinity to the surface but did not perturb the maximal surface coverage and the adsorption enthalpy. The structural and dynamic properties of the single point mutants as characterized by solid-state NMR techniques were not altered either. Simultaneous replacement of all four basic amino acids with alanine lowered the adsorption equilibrium constant by 5-fold and the maximal surface coverage by nearly 2-fold. The initial exothermic phase of adsorption exhibited by native statherin is preserved in this mutant, along with the R-helical structure and the dynamic properties of the N-terminal domain. These results help to refine the two binding site model of statherin adsorptionmore »
- Authors:
- Publication Date:
- Research Org.:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Org.:
- USDOE
- OSTI Identifier:
- 909672
- Report Number(s):
- PNWD-SA-7813
Journal ID: ISSN 0006-2960; BICHAW; TRN: US200723%%126
- DOE Contract Number:
- AC05-76RL01830
- Resource Type:
- Journal Article
- Resource Relation:
- Journal Name: Biochemistry, 46(16):4725-4733; Journal Volume: 46; Journal Issue: 16
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 59 BASIC BIOLOGICAL SCIENCES; ADSORPTION; ADSORPTION ISOTHERMS; AMINO ACIDS; GENE MUTATIONS; THERMODYNAMICS
Citation Formats
Goobes, Rivka, Goobes, Gil, Shaw, Wendy J., Drobny, Gary P., Campbell, Charles T., and Stayton, Patrick. Thermodynamic Roles of Basic Amino Acids in Statherin Recognition of Hydroxyapatite. United States: N. p., 2007.
Web. doi:10.1021/bi602345a.
Goobes, Rivka, Goobes, Gil, Shaw, Wendy J., Drobny, Gary P., Campbell, Charles T., & Stayton, Patrick. Thermodynamic Roles of Basic Amino Acids in Statherin Recognition of Hydroxyapatite. United States. doi:10.1021/bi602345a.
Goobes, Rivka, Goobes, Gil, Shaw, Wendy J., Drobny, Gary P., Campbell, Charles T., and Stayton, Patrick. Tue .
"Thermodynamic Roles of Basic Amino Acids in Statherin Recognition of Hydroxyapatite". United States.
doi:10.1021/bi602345a.
@article{osti_909672,
title = {Thermodynamic Roles of Basic Amino Acids in Statherin Recognition of Hydroxyapatite},
author = {Goobes, Rivka and Goobes, Gil and Shaw, Wendy J. and Drobny, Gary P. and Campbell, Charles T. and Stayton, Patrick},
abstractNote = {Salivary statherin is a highly acidic, 43 amino acid residue protein that functions as an inhibitor of primary and secondary crystallization of the biomineral hydroxyapatite. The acidic domain at the N-terminus was previously shown to be important in the binding of statherin to hydroxyapatite surfaces. This acidic segment is followed by a basic segment whose role is unclear. In this study, the role of the basic amino acids in the hydroxyapatite adsorption thermodynamics has been determined using isothermal titration calorimetry and equilibrium adsorption isotherm analysis. Single point mutations of the basic side chains to alanine lowered the binding affinity to the surface but did not perturb the maximal surface coverage and the adsorption enthalpy. The structural and dynamic properties of the single point mutants as characterized by solid-state NMR techniques were not altered either. Simultaneous replacement of all four basic amino acids with alanine lowered the adsorption equilibrium constant by 5-fold and the maximal surface coverage by nearly 2-fold. The initial exothermic phase of adsorption exhibited by native statherin is preserved in this mutant, along with the R-helical structure and the dynamic properties of the N-terminal domain. These results help to refine the two binding site model of statherin adsorption proposed earlier in our study of wild-type statherin (Goobes, R., Goobes, G., Campbell, C.T., and Stayton, P.S. (2006) Biochemistry 45, 5576-5586). The basic charges function to reduce protein-protein charge repulsion on the HAP surface, and in their absence, there is a considerable decrease in statherin packing density on the surface at binding saturation. Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.},
doi = {10.1021/bi602345a},
journal = {Biochemistry, 46(16):4725-4733},
number = 16,
volume = 46,
place = {United States},
year = {Tue Apr 24 00:00:00 EDT 2007},
month = {Tue Apr 24 00:00:00 EDT 2007}
}
-
Acidic proteins found in mineralized tissues act as nature's crystal engineers, where they play a key role in promoting or inhibiting the growth of minerals such as hydroxyapatite (HAP), Ca10(PO4)6- (OH)2, the main mineral component of bone and teeth. There is remarkably little known about the protein structure-function relationships and the recognition processes governing hard tissue engineering. It is well-known that several salivary proteins (statherin) and peptides (SN-15, N-terminal 15 amino fragment of statherin) bind strongly to HAP to regulate crystal growth.1 In this work, we describe how solid-state NMR can be used to identify which amino acid side chainsmore »
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A Solid-State NMR Study of the Dynamics and Interactions of Phenylalanine Rings in a Statherin Fragment Bound to Hydroxyapatite Crystals
Extracellular matrix proteins regulate hard tissue growth by acting as adhesion sites for cells, by triggering cell signaling pathways, and by directly regulating the primary and/or secondary crystallization of hydroxyapatite, the mineral component of bone and teeth. Despite the key role that these proteins play in the regulation of hard tissue growth in humans, the exact mechanism used by these proteins to recognize mineral surfaces is poorly understood. Interactions between mineral surfaces and proteins very likely involve specific contacts between the lattice and the protein side chains, so elucidation of the nature of interactions between protein side chains and theirmore » -
Homonuclear and Heteronuclear NMR Studies of a Statherin Fragment Bound to Hydroxyapatite Crystals
Acidic proteins found in mineralized tissues act as nature's crystal engineers, where they play a key role in promoting or inhibiting the growth of minerals such as hydroxyapatite (HAP), Ca10(PO4)6(OH)2, the main mineral component of bone and teeth. Key to understanding the structural basis of protein-crystal recognition and protein control of hard tissue growth is the nature of interactions between the protein side chains and the crystal surface. In an earlier work we have measured the proximity of the lysine (K6) side chain in an SN-15 peptide fragment of the salivary protein statherin adsorbed to the Phosphorus-rich surface of HAPmore » -
Structure and Dynamics of Hydrated Statherin on Hydroxyapatite As Determined by Solid-State NMR
Proteins directly conrol the nucleation and growth of biominerals, but the details of molecular recognition at the protein-biomineral interface reamain poorly understood. The elucidation of recognition mechanisms at this interface may provide design principles for advanced materials development in medical and ceramic composite technologies. Here, we have used solid-state NMR techniques to provide the first high-resolution structural and dynamic characterization of a hydrated biomineralization protein, salivary statherin, adsorbed to its biologically relevant hydroxypapatite (HAP) surface. Backbone secondary structure for the N-terminal dodecyl region was determined using a combination of homonuclear and heteronuclear dipolar recoupling techniques. Both sets of experiments indicatemore »