Specificity of Translation for N-Alkyl Amino Acids

• Published in: Journal of the American Chemical Society Vol. 129; no. 37; pp. 11316 - 11317
• Main Authors: Zhang, Baolin, Tan, Zhongping, Dickson, Lucas Gartenmann, Nalam, Madhavi N. L, Cornish, Virginia W, Forster, Anthony C
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 19.09.2007
• Subjects: Amino Acids - biosynthesis; Amino Acids - chemistry; Amino Acids - genetics; Escherichia coli - genetics; Proline - biosynthesis; Proline - chemistry; Proline - genetics; Protein Biosynthesis; RNA, Messenger - genetics; RNA, Transfer - genetics; RNA, Transfer, Amino Acyl - genetics; Transcription, Genetic
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja073487l

We examine the specificity of translation for various primary and secondary amino acid analogues. A synthetase-free, pure, E. coli translation system is used to prevent competing reactions, and three different tRNA adaptor:codon pairs are used to control for tRNA- and codon-specific effects. Surprisingly, N-butyl amino acids fail to incorporate, N-methyl amino acid incorporation efficiencies are dependent on the tRNA adaptor, yet hydroxyPro, Pro, Phe, and Ala incorporate near quantitatively from all adaptors. This suggests that Pro is a privileged N-alkyl amino acid for incorporation by the translation apparatus and establishes that very efficient N-methyl amino acid incorporation is possible if matched with an optimal tRNA adaptor. Results support exploration of Pro analogues and N-methyl amino acids as substrates for engineering ribosomal synthesis of genetically selectable libraries of protease-resistant, N-alkyl peptide ligands.