کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1316507 | 976464 | 2008 | 12 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Accommodation of Ca(II) ions for catalytic activity by a group I ribozyme
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی معدنی
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چکیده انگلیسی
The wildtype Tetrahymena ribozyme cannot catalyze detectable levels of phosphotransfer activity in vitro on an exogenous RNA substrate oligonucleotide when calcium(II) is supplied as the only available divalent ion. Nevertheless, low-error mutants of this ribozyme have been acquired through directed evolution that do have activity in 10Â mM CaCl2. The mechanisms for such Ca(II) accommodation are not known. Here, we assayed the entire molecule in an effort to identify the roles of the mutations in allowing catalytic activity in Ca(II). We used four biochemical probing techniques - native-gel electrophoresis, hydroxyl radical footprinting, terbium(III) cleavage footprinting, and phosphorothioate interference mapping - to compare the solution structure of the wildtype ribozyme with that of a Ca(II)-active five-site mutant. We compared the gross folding patterns and specific metal-binding sites in both MgCl2 and CaCl2 solutions. We detected no large-scale folding differences between the two RNAs in either metal. However, we did discover a limited number of local folding differences, involving regions of the RNA affected by positions 42, 188, and 270. These data support the notion that Ca(II) is accommodated by the Tetrahymena ribozyme by a slight breathing at the active site, but that alterations at, near to, and distal from the active site can all contribute to Ca(II)-based activity.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Inorganic Biochemistry - Volume 102, Issue 7, July 2008, Pages 1495-1506
Journal: Journal of Inorganic Biochemistry - Volume 102, Issue 7, July 2008, Pages 1495-1506
نویسندگان
Paul Cernak, Rowan A. Madix, Louis Y. Kuo, Niles Lehman,