Romby P, Westhof E, Moras D, Giegé R, Houssier C, Grosjean H
Institut de Biologie Moléculaire et Cellulaire du CNRS, Strasbourg, France.
J Biomol Struct Dyn. 1986 Oct;4(2):193-203. doi: 10.1080/07391102.1986.10506339.
The temperature-jump method was used to compare the stability of anticodon-anticodon duplexes formed by the self-association of two tRNAs: yeast tRNA-Asp and Escherichia coli tRNA-Gly. Yeast tRNA-Asp duplexes contain a U/U mismatch while E. coli tRNA-Gly dimers have a C/C mismatch in the middle position of their quasi self-complementary anticodons GUC and GCC, respectively. At neutral pH, it is found that only tRNA-Asp duplexes exist whereas at pH 5.0 only tRNA-Gly duplexes are formed. This reflects the hemiprotonation of the N3 of the cytosines at pH 5.0 which induces a pairing between the two middle residues of the anticodon GCC in E. coli tRNA-Gly. This is the first evidence that a protonated C-C(+) base pair is compatible with the formation of a double helix with antiparallel strands in a natural RNA molecule.
采用温度跳跃法比较了由两种tRNA（酵母天冬氨酸tRNA和大肠杆菌甘氨酸tRNA）自缔合形成的反密码子-反密码子双链体的稳定性。酵母天冬氨酸tRNA双链体含有一个U/U错配，而大肠杆菌甘氨酸tRNA二聚体在其准自我互补反密码子GUC和GCC的中间位置分别有一个C/C错配。发现在中性pH值下，仅存在酵母天冬氨酸tRNA双链体，而在pH 5.0时，仅形成大肠杆菌甘氨酸tRNA双链体。这反映了在pH 5.0时胞嘧啶N3的半质子化，其诱导了大肠杆菌甘氨酸tRNA中反密码子GCC的两个中间残基之间的配对。这是第一个证据，表明质子化的C-C(+)碱基对与天然RNA分子中反平行链双螺旋的形成是相容的。
