Interaction between human tRNA synthetases involves repeated sequence elements

Seung Bae Rho, Kyoung Hoa Lee, Jung Woo Kim, Kiyotaka Shiba, Yeong Joon Jo, Sunghoon Kim

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Aminoacyl-tRNA synthetases (tRNA synthetases) of higher eukaryotes form a multiprotein complex. Sequence elements that are responsible for the protein assembly were searched by using a yeast two-hybrid system. Human cytoplasmic isoleucyl-tRNA synthetase is a component of the multi-tRNA synthetase complex and it contains a unique C-terminal appendix. This part of the protein was used as bait to identify an interacting protein from a HeLa cDNA library. The selected sequence represented the internal 317 amino acids of human bifunctional (glutamyl- and prolyl-) tRNA synthetase, which is also known to be a component of the complex. Both the C-terminal appendix of the isoleucyl-tRNA synthetase and the internal region of bifunctional tRNA synthetase comprise repeating sequence units, two repeats of about 90 amino acids, and three repeals of 57 amino acids, respectively. Each repeated motif of the two proteins was responsible for the interaction, but the stronger interaction was shown by the native structures containing multiple motifs. Interestingly, the N-terminal extension of human glycyl-tRNA synthetase containing a single motif homologous to those in the bifunctional tRNA synthetase also interacted with the C-terminal motif of the isoleucyl-tRNA synthetase although the enzyme is not a component of the complex. The data indicate that the multiplicity of the binding motif in the tRNA synthetases is necessary for enhancing the interaction strength and may be one of the determining factors for the tRNA synthetases to be involved in the formation of the multi-tRNA synthetase complex.

Original languageEnglish
Pages (from-to)10128-10133
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number19
Publication statusPublished - 1996 Sept 17

All Science Journal Classification (ASJC) codes

  • General


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