Evaluation of a peptide motif designed for protein tethering to polymer surfaces

Abstract

In search for peptide motifs that allow us to efficiently tether fusion proteins onto polymer surfaces, we designed a KLKLKLKLKL (KL5) decapeptide in which basic and hydrophobic amino acids were alternately linked. By means of genetic engineering technology together with a bacterial expression system, the KL5 fusions of epidermal growth factor (EGF), basic fibroblast growth factor, and stromal cell-derived factor-1α were prepared together with their control counterparts without KL5. The adsorption experiments were performed for these fusion proteins on the surface of polystyrene, hydrophilized polystyrene, and polycaprolactone by surface plasmon resonance analysis. To understand the results of the binding assays, the structure of the fusion proteins was predicted by ab initio computer simulation and analyzed empirically by circular dichroism spectroscopy. The result of structural analyses suggested that the KL5 peptide is exposed to the outside and has a negligible effect on the structure of the protein partners. However, it was found that the efficiency of KL5 as a peptide motif greatly depends on protein partners. Our results showed that KL5 exerts most effectively its function as a peptide motif when fused to acidic proteins such as EGF. Indeed, the number of living human mesenchymal stem cells determined after 7-day culture was larger on the polystyrene and polycaprolactone surfaces with EGF tethered through the KL5 peptide than control surfaces. According to the results obtained in this study, we conclude that KL5 is useful as a peptide motif for tethering a specific class of protein partners.

Keywords:

• Surface modification
• bioactive surface
• fusion protein
• genetic engineering
• peptide motif
• mesenchymal stem cell

Disclosure statement

The authors declare no potential conflicts of interest.

Data availability statement

The authors confirm that the data supporting the finding of this study are available within the article. The supporting information on the experimental methods is also included in Supplementary Materials file.

Additional information

Funding

The part of this work was supported by Japan Society for the Promotion of Science (JSPS) KAKENHI Grant Number JP25293403 and JP16H03182.