Analyses of Conditions for KMSSS Loop in Tyrosyl-tRNA Synthetase by Building a Mutant Library

The KMSKS motif is the ATP binding motif for aminoacylation process of class I aminoacyl-tRNA synthetases. Although researches based on natural proteins inform us about the contribution of natural amino acid sequences for the catalysis, they have difficulties in discussing the other alternative sequ...

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Bibliographic Details
Published in:Journal of biochemistry (Tokyo) 2009-08, Vol.146 (2), p.241-250
Main Authors: Kamijo, Shunsuke, Fujii, Akihiko, Onodera, Kenji, Wakabayashi, Kenichi
Format: Article
Language:English
Subjects:
amber suppression
amino-acyl tRNA Synthetase
ATP binding motif
Base Sequence
KMSKS loop
Methanococcus - chemistry
Methanococcus - enzymology
Methanococcus - genetics
Methanococcus - metabolism
Molecular Sequence Data
Mutation - genetics
mutational analysis
Peptide Library
Protein Subunits - genetics
Tyrosine-tRNA Ligase - chemistry
Tyrosine-tRNA Ligase - genetics
Tyrosine-tRNA Ligase - metabolism
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Summary:The KMSKS motif is the ATP binding motif for aminoacylation process of class I aminoacyl-tRNA synthetases. Although researches based on natural proteins inform us about the contribution of natural amino acid sequences for the catalysis, they have difficulties in discussing the other alternative sequences and prohibited sequences for the motif to maintain the catalytic ability. In order to reveal such the conditions for the alternative and prohibited sequences, it is important to investigate a library of various mutants for the motif. For that purpose, we build a library of more than 200 mutants substituting the KMSSS loop, Lys204-Met205-Ser206-Ser207-Ser208, in tyrosyl-tRNA synthetase of Methanococcus jannaschii, and their catalytic abilities were examined by the Amber suppression method. Mutants of K204R and K204N still maintained catalytic abilities to a certain extent. On the other hand, a variety of alternative sequences for Ser206-Ser207-Ser208 were obtained, and some of those did not include either Ser or Thr, which were regarded as necessary residues in the KMSKS motif in previous works. In this article, catalytic activity of all the mutants are represented in detail and some suggestions for the condition of the motif are discussed.
ISSN:0021-924X
1756-2651
DOI:10.1093/jb/mvp063