Control of Collagen Stability and Heterotrimer Specificity through Repulsive Electrostatic Interactions.

Avanish S Parmar,Nida F Hasan,Patrick L Nosker,Vikas Nanda,Mihir Joshi

doi:10.3390/biom3040986

Avanish S Parmar, Nida F Hasan + Show 3 more

Open Access

https://doi.org/10.3390/biom3040986

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Journal: Biomolecules	Publication Date: Dec 6, 2013
Citations: 36	License type: CC BY 4.0

Affiliation: Rutgers, The State University of New Jersey

Abstract

Charge-pair interactions between acidic and basic residues on the surface of collagen can promote stability as well as control specificity of molecular recognition. Heterotrimeric collagen peptides have been engineered de novo using either rational or computational methods, which in both cases optimize networks of favorable charge-pair interactions in the target structure. Less understood is the role of electrostatic repulsion between groups of like charge in destabilizing structure or directing molecular recognition. To study this, we apply a “charge crowding” approach, where repulsive interactions between multiple aspartate side chains are found to destabilize the homotrimer states in triple helical peptide system and can be utilized to promote the formation of heterotrimers. Neutralizing surface charge by increasing salt concentration or decreasing pH can enhance homotrimer stability, confirming the role of charge crowding on the destabilization of homotrimers via electrostatic repulsion. Charge crowding may be used in conjunction with other approaches to create specific collagen heterotrimers.

Highlights

Collagen is the most abundant protein in the human body, accounting for approximately one-third of protein mass [1]
Utilizing the surface electrostatic interactions, charged heterotrimers have been designed by forming a network of electrostatics on the surface of triple helix [13,14,15,16,17,18,19,20]
Our result suggests that charge crowding on N- and C-terminal peptides significantly destabilizes the triple helical structure, whereas charged amino acids in the middle of the sequence can disrupt the formation of triple helical structure

Summary

Introduction

Collagen is the most abundant protein in the human body, accounting for approximately one-third of protein mass [1]. Extensive study of de novo α-helical coiled coils shows that peptide systems assemble using electrostatic forces, both to encourage specific association of the desired state and prevent competing states. Similar to the case of a coiled-coil, we suspect the collagen triple-helix folds in part due to interchain repulsive and attractive forces. Utilizing the surface electrostatic interactions, charged heterotrimers have been designed by forming a network of electrostatics on the surface of triple helix [13,14,15,16,17,18,19,20]. Favorable attractive electrostatics interactions were utilized to form a specific heterotrimer. To isolate the impact of repulsive interactions, three collagen peptides were designed to include acidic triplets either flanking or in between Pro-Hyp-Gly sequence repeats. We believe that charge crowding can be used in conjunction with other methods to design specific heterotrimers by destabilizing competing states and favoring targeted state

Design Strategy

Structure and Stability

Ionic Strength Dependence

Assembly at Low pH

Peptide Synthesis and Sequences

Conclusions