Architecture of a Diels-Alderase ribozyme with a preformed catalytic pocket.
نویسندگان
چکیده
Artificial ribozymes catalyze a variety of chemical reactions. Their structures and reaction mechanisms are largely unknown. We have analyzed a ribozyme catalyzing Diels-Alder cycloaddition reactions by comprehensive mutation analysis and a variety of probing techniques. New tertiary interactions involving base pairs between nucleotides of the 5' terminus and a large internal loop forming a pseudoknot fold were identified. The probing data indicate a preformed tertiary structure that shows no major changes on substrate or product binding. Based on these observations, a molecular architecture featuring a Y-shaped arrangement is proposed. The tertiary structure is formed in a rather unusual way; that is, the opposite sides of the asymmetric internal loop are clamped by the four 5'-terminal nucleotides, forming two adjacent two base-pair helices. It is proposed that the catalytic pocket is formed by a wedge within one of these helices.
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ورودعنوان ژورنال:
- Chemistry & biology
دوره 11 9 شماره
صفحات -
تاریخ انتشار 2004