A Rationally Designed Pyrrolysyl-tRNA Synthetase Mutant with a Broad Substrate Spectrum

Wang, Yane‐Shih; Fang, Xinqiang; Wallace, Ashley L.; Wu, Bo; Liu, Wenshe Ray

doi:10.1021/ja211972x

Cited by 135 publications

(165 citation statements)

References 37 publications

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“…This conclusion is supported by a recent report (34) showing the PylRS variant Asn346Ala/Cys348Ala to possess significant activity with 3-I-Phe yet weak activity with Phe. Based on these data, we created PylRS mutant libraries that randomized active site positions, including N346 and C348 (SI Methods).…”

Section: Resultssupporting

confidence: 71%

Polyspecific pyrrolysyl-tRNA synthetases from directed evolution

Guo¹,

Wang²,

Nakamura³

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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107

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Pyrrolysyl-tRNA synthetase (PylRS) and its cognate tRNA Pyl have emerged as ideal translation components for genetic code innovation. Variants of the enzyme facilitate the incorporation >100 noncanonical amino acids (ncAAs) into proteins. PylRS variants were previously selected to acylate N e -acetyl-Lys (AcK) onto tRNA Pyl . Here, we examine an N e -acetyl-lysyl-tRNA synthetase (AcKRS), which is polyspecific (i.e., active with a broad range of ncAAs) and 30-fold more efficient with Phe derivatives than it is with AcK. Structural and biochemical data reveal the molecular basis of polyspecificity in AcKRS and in a PylRS variant [iodo-phenylalanyl-tRNA synthetase (IFRS)] that displays both enhanced activity and substrate promiscuity over a chemical library of 313 ncAAs. IFRS, a product of directed evolution, has distinct binding modes for different ncAAs. These data indicate that in vivo selections do not produce optimally specific tRNA synthetases and suggest that translation fidelity will become an increasingly dominant factor in expanding the genetic code far beyond 20 amino acids.aminoacyl-tRNA synthetase | genetic code | genetic selection | posttranslational modification | synthetic biology T he standard genetic code table relates the 64 nucleotide triplets to three stop signals and 20 canonical amino acids. Some organisms, including humans, naturally evolved expanded genetic codes that accommodate 21 amino acids (1), or possibly 22 amino acids in rare cases (2). Engineering translation system components, including tRNAs (3, 4), aminoacyl-tRNA synthetases (AARSs) (5, 6), elongation factors (7), and the ribosome itself (8), have produced organisms with artificially expanded genetic codes. Products of genetic code engineering include bacterial, yeast, and mammalian cells and animals that are able to synthesize proteins with sitespecifically inserted noncanonical amino acids (ncAAs) (9).Genetic code expansion systems rely on an orthogonal AARS/ tRNA pair (o-AARS, o-tRNA) (5, 6). The o-AARS should be specific in ligating a desired ncAA to a stop codon decoding tRNA, and both the o-tRNA and o-AARS are assumed not to cross-react with endogenous AARSs or tRNAs. Although some AARSs evolved in nature to recognize certain ncAAs (10-12), many genetic code expansion systems require a mutated AARS active site. The active site of the o-AARS is usually redesigned via directed evolution (6), including positive and negative selective rounds, to produce an enzyme that is assumed to be specific for an ncAA and not active with the 20 canonical amino acids. Genetic code expansion technology is rapidly evolving (13), and the ability to incorporate multiple ncAAs into a protein using quadruplet-codon decoding (14) or sense-codon recoding (15-19) is now becoming feasible. Protein synthesis with multiple ncAAs will require o-AARSs that are able to discriminate their ncAA substrate not only from canonical amino acids in the cell but from other ncAAs that are added to the cell.Probing the effects of amino acid analogs on bacterial cell...

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Section: Resultssupporting

confidence: 71%

Polyspecific pyrrolysyl-tRNA synthetases from directed evolution

Guo¹,

Wang²,

Nakamura³

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

107

146

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“…62b, 64 As proof of principle, peptides containing tetrazine, hydroxylamine, and maleimide functionalities were incubated in a single solution with the reactive partners trans-cyclooctene, isovaleraldehyde, and cyclopentadiene. These reactive functionalities ligated selectively and rapidly (30 minutes) in aqueous solution in good yield with their reactive partners in the presence of the alternative reactive groups.…”

Section: Resultsmentioning

confidence: 99%

Proline Editing: A General and Practical Approach to the Synthesis of Functionally and Structurally Diverse Peptides. Analysis of Steric versus Stereoelectronic Effects of 4-Substituted Prolines on Conformation within Peptides

et al. 2013

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Functionalized proline residues have diverse applications. Herein we describe a practical approach, proline editing, for the synthesis of peptides with stereospecifically modified proline residues. Peptides are synthesized by standard solid-phase-peptide-synthesis to incorporate Fmoc-Hydroxyproline (4R-Hyp). In an automated manner, the Hyp hydroxyl is protected and the remainder of the peptide synthesized. After peptide synthesis, the Hyp protecting group is orthogonally removed and Hyp selectively modified to generate substituted proline amino acids, with the peptide main chain functioning to “protect” the proline amino and carboxyl groups. In a model tetrapeptide (Ac-TYPN-NH2), 4R-Hyp was stereospecifically converted to 122 different 4-substituted prolyl amino acids, with 4R or 4S stereochemistry, via Mitsunobu, oxidation, reduction, acylation, and substitution reactions. 4-Substituted prolines synthesized via proline editing include incorporated structured amino acid mimetics (Cys, Asp/Glu, Phe, Lys, Arg, pSer/pThr), recognition motifs (biotin, RGD), electron-withdrawing groups to induce stereoelectronic effects (fluoro, nitrobenzoate), handles for heteronuclear NMR (19F:fluoro; pentafluorophenyl or perfluoro-tert-butyl ether; 4,4-difluoro; 77SePh) and other spectroscopies (fluorescence, IR: cyanophenyl ether), leaving groups (sulfonate, halide, NHS, bromoacetate), and other reactive handles (amine, thiol, thioester, ketone, hydroxylamine, maleimide, acrylate, azide, alkene, alkyne, aryl halide, tetrazine, 1,2-aminothiol). Proline editing provides access to these proline derivatives with no solution phase synthesis. All peptides were analyzed by NMR to identify stereoelectronic and steric effects on conformation. Proline derivatives were synthesized to permit bioorthogonal conjugation reactions, including azide-alkyne, tetrazinetrans-cyclooctene, oxime, reductive amination, native chemical ligation, Suzuki, Sonogashira, cross-metathesis, and Diels-Alder reactions. These proline derivatives allowed three parallel bioorthogonal reactions to be conducted in one solution.

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“…32, 33 More recently, it has been discovered that as a consequence of other ncAAs being absent from the negative selection, some aaRSs exhibit a degree of polyspecificity towards structurally related ncAAs. 34–41 One such aaRS, evolved to encode p -cyanophenylalanine in E. coli , is capable of incorporating over 20 aromatic amino acid derivatives. 34, 37 Another such pair is the PylRS/tRNA CUA pair from certain methanogens (notably Methanosarcina barkeri ( Mb ), and Methanosarcina mazei ( Mm )).…”

Section: Expanding the Genetic Codementioning

confidence: 99%

Playing with the Molecules of Life

2018

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Our understanding of the complex processes of living organisms at the molecular level is growing exponentially. This knowledge, together with a powerful arsenal of tools for manipulating the structures of macromolecules, is allowing chemists to harness and reprogram the cellular machinery. Here we review one example in which the genetic code itself has been expanded with new building blocks that allow us to probe and manipulate the structures and functions of proteins in ways previously unimaginable

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A Rationally Designed Pyrrolysyl-tRNA Synthetase Mutant with a Broad Substrate Spectrum

Cited by 135 publications

References 37 publications

Polyspecific pyrrolysyl-tRNA synthetases from directed evolution

Polyspecific pyrrolysyl-tRNA synthetases from directed evolution

Proline Editing: A General and Practical Approach to the Synthesis of Functionally and Structurally Diverse Peptides. Analysis of Steric versus Stereoelectronic Effects of 4-Substituted Prolines on Conformation within Peptides

Playing with the Molecules of Life

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