Wrzesinski J, Michałowski D, Ciesiołka J, Krzyzosiak W J
Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland.
FEBS Lett. 1995 Oct 23;374(1):62-8. doi: 10.1016/0014-5793(95)01077-r.
The specificity and efficiency of manganese ion-induced RNA hydrolysis was studied with several tRNA molecules. In case of yeast tRNA(Phe), the main cleavage occurs at p16 and minor cuts at p17-18, p20-21, p34 and p36-37. The major Mn(II)-induced cut in yeast elongator tRNA(Met) is also located in the D-loop at p16 and it is stronger than that observed in tRNA(Phe). In initiator tRNA(Met) from yeast two strong Mn(II) cleavages of equal intensity occur at p16 and p17. This is in contrast with single, much weaker cuts induced in the D-loop of that tRNA by Mg(II), Eu(III) and Pb(II) ions. Interestingly, in case of yeast tRNA(Glu) the main cleavage caused by Mn(II), Mg(II) and Pb(II) ions occurs in the anticodon loop. The involvement of hypermodified base mnm5s2U in this cleavage was ruled out based on results obtained with in vitro transcript of yeast tRNA(Glu) anticodon arm. Mutation of a single base A37G in the anticodon loop of the transcript drastically reduced the specificity of Mn(II)-induced hydrolysis.
用几种转运RNA（tRNA）分子研究了锰离子诱导的RNA水解的特异性和效率。对于酵母苯丙氨酸tRNA（tRNA(Phe)），主要切割发生在p16处，次要切割发生在p17 - 18、p20 - 21、p34和p36 - 37处。酵母延伸因子甲硫氨酸tRNA（tRNA(Met)）中主要的锰（II）诱导切割也位于D环的p16处，且比在tRNA(Phe)中观察到的更强。在酵母起始甲硫氨酸tRNA（tRNA(Met)）中，在p16和p17处出现两个强度相等的强锰（II）切割。这与镁（II）、铕（III）和铅（II）离子在该tRNA的D环中诱导的单一且弱得多的切割形成对比。有趣的是，对于酵母谷氨酸tRNA（tRNA(Glu)），锰（II）、镁（II）和铅（II）离子引起的主要切割发生在反密码子环中。基于酵母tRNA(Glu)反密码子臂的体外转录本获得的结果，排除了超修饰碱基mnm5s2U参与这种切割的可能性。转录本反密码子环中单个碱基A37G的突变极大地降低了锰（II）诱导水解的特异性。
