Genetic Incorporation of Histidine Derivatives Using an Engineered Pyrrolysyl-tRNA Synthetase

Abstract

A polyspecific amber suppressor aminoacyl-tRNA synthetase/tRNA pair was evolved that genetically encodes a series of histidine analogues in both Escherichia coli and mammalian cells. In combination with tRNACUAPyl, a pyrrolysyl-tRNA synthetase mutant was able to site-specifically incorporate 3-methyl-histidine, 3-pyridyl-alanine, 2-furyl-alanine, and 3-(2-thienyl)-alanine into proteins in response to an amber codon. Substitution of His66 in the blue fluorescent protein (BFP) with these histidine analogues created mutant proteins with distinct spectral properties. This work further expands the structural and chemical diversity of unnatural amino acids (UAAs) that can be genetically encoded in prokaryotic and eukaryotic organisms and affords new probes of protein structure and function.

Genetic Incorporation of ε-N-2-Hydroxyisobutyryl-lysine into Recombinant Histones

“…21, 27 pLeiG-GFP-Asp134TAG encodes a proK promoter-driven tRNA CUA Pyl expression cassette and a GFP variant with a C-terminal hexahistidine-tag and an amber codon at a permissive site, Asp134. A quantitative fluorescence assay was carried out in minimal media in the presence and absence of 1 mM HibK, and an increase in fluorescence was observed for both HibKRS-1 and HibKRS-2 in the presence of the UAA.…”

At the Interface of Chemical and Biological Synthesis: An Expanded Genetic Code

“…1B) (Wang et al 2006b;Liu and Schultz 2010;Wan et al 2014). To further expand the number and nature of genetically encoded ncAAs, aaRS/tRNA pairs from other archeal and eukaryotic organisms have been recently developed, including Pyrococcus horikoshii lysyl aaRS/tRNA, P. horikoshii glutamyl aaRS/tRNA, Saccharomyces cerevisiae tryptophanyl aaRS/tRNA, heterogeneous leucyl Mt-tRNA/Hs-aaRS, and proly Af-tRNA/Ph-aaRS pairs Santoro et al 2003;Anderson et al 2004;Chatterjee et al 2012Chatterjee et al , 2013dXiao et al 2014). The structurally distinct active sites of these aaRSs allow one to encode chemically diverse amino acid side chains; however, the efficiencies with which the ncAAs can be incorporated at a given site in the proteome vary-ranging from milligrams to 5þ g/L of mutant protein, most likely because of the differing degrees to which the aaRS/tRNA pair is optimized (of course, for any given protein, efficiency is also affected by the mutation site).…”

“…By substituting core residues in the chromophores of various FPs with ncAAs, FP variants with distinct spectral properties have been generated, including FP sensors for monitoring pH, reducing and oxidizing environments, and heavy metals (Wang et al 2003;Ai 2012;Chatterjee et al 2013d;Niu and Guo 2013;Xiao et al 2014). For example, a fluorogenic biosensor sensitive to oxidation was generated by substitution of Tyr66 in GFP with p-borono-phenylalanine ( Fig.…”

Exploring the potential impact of an expanded genetic code on protein function

“…This screen was accomplished by growing DH10B cells containing the amber suppressor tRNA/PolyRS pair (encoded on the plasmid pUltra-Poly) and a superfolder green fluorescent protein (sfGFP) with an amber mutation at the permissive site Tyr-151 (encoded on plasmid pET22b-T5-sfGFP*) in LB medium supplemented with various ncAAs at a concentration of 1 mM (Fig. 1B) (13,14). The highest GFP expression levels were observed in the presence of 10 derivatives of tyrosine or phenylalanine, including p-acetyl-phenylalanine (AcF), O-methyl-tyrosine, AcrF, p-azido-phenylalanine (AzF), O-allyl-tyrosine (O-allyl-Y), p-bromophenylalanine (BrF), p-iodo-phenylalanine (IF), p-azidomethylphenylalanine (AzMeF), p-biphenylalanine, and O-tert-butyl-tyrosine (Fig.…”