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Structure of tRNA-Modifying Enzyme TiaS and Motions of Its Substrate Binding Zinc Ribbon.

A new interesting article has been published in J Mol Biol. 2018 Oct 19;430(21):4183-4194. doi: 10.1016/j.jmb.2018.08.015. Epub 2018 Aug 16. and titled:

Structure of tRNA-Modifying Enzyme TiaS and Motions of Its Substrate Binding Zinc Ribbon.

Authors of this article are:

Dong J, Li F, Gao F, Wei J, Lin Y, Zhang Y, Lou J, Liu G, Dong Y, Liu L, Liu H, Wang J, Gong W.

A summary of the article is shown below:

The accurate modification of the tRNAIle anticodon wobble cytosine 34 is critical for AUA decoding in protein synthesis. Archaeal tRNAIle2 cytosine 34 is modified with agmatine in the presence of ATP by TiaS (tRNAIle2 agmatidine synthetase). However, no structure of apo-form full-length TiaS is available currently. Here, the crystal structures of apo TiaS and a complex of TiaS-agmatine-AMPPCP-Mg are presented, with properly folded zinc ribbon and Cys4-zinc coordination identified. Compared with tRNAIle2-bound form, the architecture of apo TiaS shows a totally different conformation of zinc ribbon. Molecular dynamics simulations of the docking complex between free-state TiaS and tRNAIle2 suggest that zinc ribbon domain is capable of performing large-scale motions to sample substrate binding-competent conformation. Principle component analysis and normal mode analysis show consistent results about the relative directionality of functionally correlated zinc ribbon motions. Apo TiaS and TiaS-agmatine-AMPPCP-Mg/TiaS-AMPCPP-Mg complex structures capture two snapshots of the flexible ATP-Mg binding p2loop step-by-step stabilization. Research from this study provides new insight into TiaS functional mechanism and the dynamic feature of zinc ribbons.

Check out the article’s website on Pubmed for more information:

This article is a good source of information and a good way to become familiar with topics such as:

catalytic mechanism;conformational change;tRNA modification;zinc finger


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