In Vivo Encapsulation of Nucleic Acids Using an Engineered Nonviral Protein Capsid

• Published in: Journal of the American Chemical Society Vol. 134; no. 32; pp. 13152 - 13155
• Main Authors: Lilavivat, Seth, Sardar, Debosmita, Jana, Subrata, Thomas, Geoffrey C, Woycechowsky, Kenneth J
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 15.08.2012
• Subjects: Capsid - chemistry; Capsid Proteins - chemical synthesis; Capsid Proteins - genetics; Electrophoresis, Agar Gel; Microscopy, Electron, Transmission; Models, Biological; Models, Molecular; Multienzyme Complexes - chemical synthesis; Multienzyme Complexes - genetics; Virus Assembly
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja302743g

In Nature, protein capsids function as molecular containers for a wide variety of molecular cargoes. Such containers have great potential for applications in nanotechnology, which often require encapsulation of non-native guest molecules. Charge complementarity represents a potentially powerful strategy for engineering novel encapsulation systems. In an effort to explore the generality of this approach, we engineered a nonviral, 60-subunit capsid, lumazine synthase from Aquifex aeolicus (AaLS), to act as a container for nucleic acid. Four mutations were introduced per subunit to increase the positive charge at the inner surface of the capsid. Characterization of the mutant (AaLS-pos) revealed that the positive charges lead to the uptake of cellular RNA during production and assembly of the capsid in vivo. Surprisingly, AaLS-pos capsids were found to be enriched with RNA molecules approximately 200–350 bases in length, suggesting that this simple charge complementarity approach to RNA encapsulation leads to both high affinity and a degree of selectivity. The ability to control loading of RNA by tuning the charge at the inner surface of a protein capsid could illuminate aspects of genome recognition by viruses and pave the way for the development of improved RNA delivery systems.