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Open Access Highly Accessed Original article

High level expression and facile purification of recombinant silk-elastin-like polymers in auto induction shake flask cultures

Raul Machado1*, João Azevedo-Silva1, Cristina Correia1, Tony Collins1, Francisco Javier Arias23, Jose Carlos Rodríguez-Cabello23 and Margarida Casal1*

Author Affiliations

1 CBMA (Centre of Molecular and Environmental Biology), Department of Biology, University of Minho, Campus de Gualtar, 4710-057, Braga, Portugal

2 Bioforge (Group for Advanced Materials and Nanobiotechnology), Centro I+D, Universidad de Valladolid, Valladolid, Spain

3 Networking Research Centre on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), 47011, Valladolid, Spain

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AMB Express 2013, 3:11  doi:10.1186/2191-0855-3-11

Published: 5 February 2013

Abstract

Silk-elastin-like polymers (SELPs) are protein-based polymers composed of repetitive amino acid sequence motifs found in silk fibroin (GAGAGS) and mammalian elastin (VPGVG). These polymers are of much interest, both from a fundamental and applied point of view, finding potential application in biomedicine, nanotechnology and as materials. The successful employment of such polymers in such diverse fields, however, requires the ready availability of a variety of different forms with novel enhanced properties and which can be simply prepared in large quantities on an industrial scale. In an attempt to create new polymer designs with improved properties and applicability, we have developed four novel SELPs wherein the elastomer forming sequence poly(VPGVG) is replaced with a plastic-like forming sequence, poly(VPAVG), and combined in varying proportions with the silk motif. Furthermore, we optimised a simplified production procedure for these, making use of an autoinduction medium to reduce process intervention and with the production level obtained being 6-fold higher than previously reported for other SELPs, with volumetric productivities above 150 mg/L. Finally, we took advantage of the known enhanced stability of these polymers in developing an abridged, non-chromatographic downstream processing and purification protocol. A simple acid treatment allowed for cell disruption and the obtention of relative pure SELP in one-step, with ammonium sulphate precipitation being subsequently used to enable improved purity. These simplified production and purification procedures improve process efficiency and reduce costs in the preparation of these novel polymers and enhances their potential for application.

Keywords:
Silk-elastin-like polymers; Recombinant protein expression; Auto induction; Acid-based cell lysis; Ammonium sulphate purification; Non-chromatographic purification