Discrimination between Closely Related Cellular Metabolites by the SAM-I Riboswitch

JOURNAL OF MOLECULAR BIOLOGY

卷:396

Article

Montange, Rebecca K.¹  Mondragon, Estefania¹  van Tyne, Daria¹  Garst, Andrew D.¹  Ceres, Pablo¹  Batey, Robert T.¹ 

[1] Univ Colorado, Dept Chem & Biochem, Boulder, CO 80309 USA

关键词: non-protein-coding RNA;    X-ray crystallography;    isothermal titration calorimetry;    riboregulation;    S-adenosylmethionine;   

DOI  :  10.1016/j.jmb.2009.12.007

来源: Elsevier

【 摘 要 】

The SAM-I riboswitch is a cis-acting element of genetic control found in bacterial mRNAs that specifically binds S-adenosylmethionine (SAM). We previously determined the 2.9-angstrom X-ray crystal structure of the effector-binding domain of this RNA element, revealing details of RNA-ligand recognition. To improve this structure, variations were made to the RNA sequence to alter lattice contacts, resulting in a 0.5-angstrom improvement in crystallographic resolution and allowing for a more accurate refinement of the crystallographic model. The basis for SAM specificity was addressed by a structural analysis of the RNA complexed to S-adenosylhomocysteine (SAH) and sinefungin and by measuring the affinity of SAM and SAH for a series of mutants using isothermal titration calorimetry. These data illustrate the importance of two universally conserved base pairs in the RNA that form electrostatic interactions with the positively charged sulfonium group of SAM, thereby providing a basis for discrimination between SAM and SAH. (C) 2009 Elsevier Ltd. All rights reserved.

【 授权许可】

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