Site-Specific Introduction of Bioorthogonal Handles to Nanopores by Genetic Code Expansion

Abstract

Site-specific functionalization of natural amino acid-containing biological nanopores is pivotal in single molecule sensing. However, pore engineering methodologies are restricted to a limited choice and introduction of unnatural chemical components is extremely difficult. Herein we report the genetic code expansion (GCE) strategy to introduce unnatural amino acid (UAA) to an octameric Mycobacterium smegmatis porin A (MspA) nanopore. GCE allows for rapid and efficient introduction of bioorthogonal reactive site (i.e., azide) to the pore rim, and conjugation of single stranded DNA or lysozyme was demonstrated. The lysozyme-conjugated pore was further used for the discrimination of different oligosaccharides, demonstrating a sensing capacity that a bare MspA nanopore does not possess. GCE with bioorthogonal handles, which has never been previously applied in the preparation of nanopores, is a versatile strategy for pore engineering and may further expand the application scenarios of nanopores.

Keywords: Genetic Code Expansion; Lysozyme; Mycobacterium smegmatis Porin A; Nanopores; Oligosaccharides.