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Publication Abstract from PubMed

A large insertion domain called connective peptide 1 (CP1) present in class Ia aminoacyl-tRNA synthetases is responsible for post-transfer editing. Leucyl-tRNA synthetases (LeuRS) from Aquifex aeolicus and Giardia lamblia possess unique 20 and 59 amino acid insertions respectively within the CP1 that are crucial for editing activity. Crystal structures of AaLeuRS-CP1 (2.4A), GlLeuRS-CP1 (2.6A) and the insertion deletion mutant AaLeuRS-CP1-Delta20 (2.5A) were solved to understand the role of these insertions in editing. Both insertions are folded as peripheral motifs located at the opposite side of the active site entrance in CP1 domain. Docking modeling and site-directed mutagenesis showed that the insertions do not interact with the substrates. Results of molecular dynamics simulations show that the intact CP1 is more dynamic than its mutant devoid of the insertion motif. Altogether, the data show a peripheral insertion without a substrate binding site or major structural role in the active site may modulate catalytic function of a protein probably from protein dynamics regulation in two respective LeuRS CP1s. Further results from Pro and Gly mutational analyses intended to reduce or increase protein flexibility are consistent with this hypothesis.

Peripheral insertion modulates editing activity of the isolated CP1 domain of leucyl-tRNA synthetase.,Liu RJ, Tan M, Du DH, Xu BS, Eriani G, Wang ED Biochem J. 2011 Aug 5. PMID:21819379^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.