Unnatural Amino Acid Incorporation into Virus-Like Particles

Abstract

Virus-like particles composed of hepatitis B virus (HBV) or bacteriophage Qβ capsid proteins have been labeled with azide-or alkyne-containing unnatural amino acids by expression in a methionine auxotrophic strain of E. coli. The substitution does not affect the ability of the particles to selfassemble into icosahedral structures indistinguishable from native forms. The azide and alkyne groups were addressed by Cu(I)-catalyzed [3 + 2] cycloaddition: HBV particles were decomposed by the formation of more than 120 triazole linkages per capsid in a location-dependent manner, whereas Qβ suffered no such instability. The marriage of these well-known techniques of sensecodon reassignment and bioorthogonal chemical coupling provides the capability to construct polyvalent particles displaying a wide variety of functional groups with near-perfect control of spacing.

Bioorthogonale Chemie – oder: in einem Meer aus Funktionalität nach Selektivität fischen

“…[229] Durch Austausch von Methioninresten gegen Aha und Hpg wurden Azide und Alkine auch in virusartige Kapside eingebaut. [230] Erste Daten lassen darauf schließen, dass Allylcystein ebenfalls als Methioninsurrogat aufgenommen und danach mög-licherweise durch Kreuzmetathese modifiziert werden kann. [217] Einige nichtnatürliche Aminosäuren weichen in ihrer Struktur zu sehr von ihren natürlichen Analoga ab, um durch natürliche aaRS-Enzyme erkannt zu werden.…”

1,2,3‐Triazoles in Peptidomimetic Chemistry

“…In addition, the azide and alkyne precursors required for their synthesis are relatively inert, making the Huisgen cycloaddition bio-orthogonal. The Huisgen cycloaddition can be carried out in vitro under CuAAC conditions, [23][24][25][26][27][28][29][30][31][32] and examples of a copper-free, in situ Click reaction have been reported in which the reaction is catalysed by bringing the reaction partners into close proximity on a protein surface. [33,34] Reaction conditions have recently been developed that allow in vivo Huisgen cycloaddition of strained cyclic alkynes that are highly reactive towards azides in the absence of a catalyst [35,36] with application to the selective labelling of biomolecules in live mice.…”

The True Story and Advantages of RNA Phage Capsids as Nanotools

“…Moreover, a set of advanced His 6 -tagged Qβ VLPs was generated, and their ability to complex metal-derivatized compounds was confirmed [177,178]. In parallel, VLP vector capacity for chemical coupling was broadened by the introduction of azide- or alkyne-containing unnatural amino acids, which was achieved by expression of the Qβ CP gene in a methionine auxotrophic strain of E. coli [179]. …”