Brunel C, Romby P, Westhof E, Romaniuk P J, Ehresmann B, Ehresmann C
Institut de Biologie Moléculaire et Cellulaire du CNRS, Strasbourg, France.
J Mol Biol. 1990 Sep 5;215(1):103-11. doi: 10.1016/S0022-2836(05)80099-3.
In order to test and refine the molecular model of Xenopus laevis 5 S rRNA proposed in a previous work, we have synthesized, by site-directed mutagenesis and in vitro transcription, four mutants in the internal loop B and in the hairpin loop C of domain 2. The conformations of these mutant 5 S rRNAs have been tested using a variety of enzymatic and chemical structure-specific probes and computer modeling. The mutations induce conformational changes restricted to the mutated regions. Our results demonstrate unambiguously that the three helical domains of the Y-shaped structure are independent and that loop C possesses an intrinsic conformation, which is not involved in any tertiary long-range interaction. They point to the crucial role of invariant nucleotides in maintaining the intrinsic conformation of the loop and to the effect of sequence on the stability of loop regions.
为了测试和完善先前工作中提出的非洲爪蟾5S rRNA的分子模型，我们通过定点诱变和体外转录，在结构域2的内环B和发夹环C中合成了四个突变体。这些突变型5S rRNA的构象已使用各种酶促和化学结构特异性探针以及计算机建模进行了测试。这些突变诱导的构象变化仅限于突变区域。我们的结果明确表明，Y形结构的三个螺旋结构域是独立的，并且环C具有固有构象，该构象不参与任何三级长程相互作用。它们指出了不变核苷酸在维持环的固有构象中的关键作用以及序列对环区域稳定性的影响。
