Abstract
Membrane proteins play pivotal roles in cellular processes and are key targets for drug discovery. However, the reliable synthesis and folding of membrane proteins are significant problems that need to be addressed owing to their extremely high hydrophobic properties, which promote irreversible aggregation in hydrophilic conditions. Previous reports have suggested that protein aggregation could be prevented by including exogenous liposomes in cell-free translation processes. Systematic studies that identify which membrane proteins can be rescued from irreversible aggregation during translation by liposomes would be valuable in terms of understanding the effects of liposomes and developing applications for membrane protein engineering in the context of pharmaceutical science and nanodevice development. Therefore, we performed a comprehensive study to evaluate the effects of liposomes on 85 aggregation-prone membrane proteins from Escherichia coli by using a reconstituted, chemically defined cell-free translation system. Statistical analyses revealed that the presence of liposomes increased the solubility of >90% of the studied membrane proteins, and ultimately improved the yields of the synthesized proteins. Bioinformatics analyses revealed significant correlations between the liposome effect and the physicochemical properties of the membrane proteins.
Highlights
Appropriate interactions between lipids and the proteins are required to facilitate correct and functional folding of membrane proteins during synthesis[14,15]
We have reported that some expressed membrane proteins such as apo-cytochrome b525, connexin 4326,27 or bacteriorhodopsin[28] were directly incorporated into liposomes
Four membrane proteins (YfbF, CyoE, ZnuB, and DinF), which were randomly selected from the E. coli integral membrane protein library, were synthesized in the cell-free protein synthesis using recombinant element (PURE) system at 37 °C for 120 min in the absence or presence of liposomes
Summary
Appropriate interactions between lipids and the proteins are required to facilitate correct and functional folding of membrane proteins during synthesis[14,15]. We examined the expression of 85 membrane proteins from E. coli in a reconstituted cell-free translation system, which only contained the factors essential for protein synthesis This was necessary to evaluate the effects of liposomes in uniform conditions, because debris, which is often present in other translation systems, obstructs the direct analysis of the effects of liposomes. This “cell-free proteome” approach[35], in which the translation properties of relatively large number of membrane proteins are examined individually in the same cell-free translation conditions, are vital to validate the general applicability of the LCC system. The statistical analyses performed in this study revealed some intriguing results in terms of the production of membrane proteins and the relationship between the enhanced solubility in the presence of liposomes and the physicochemical properties of membrane proteins
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
