Chernukhin v A, Seggewiss J, Kashirina Iu G, Gonchar D A, Degtiarev S Kh
Mol Biol (Mosk). 2009 Jan-Feb;43(1):10-8.
The operon of nickase-modification system from Bacillus stearothermophilus SE-589 (recognition site 5'-GAGTC-3') includes two DNA methyltransferase genes: bstSEIM1 and bstSEIM2. Gene encoding DNA methyltransferase M2.BstSEI was cloned in pJW vector and expressed in E. coli cells. The enzyme M2.BstSEI has been isolated by chromatographic purification. M2.BstSEI displays maximum activity at 55 degrees C and pH 7.5. The enzyme modifies adenine in DNA sequence 5'-GAGTC-3' and has substrate specificity 5'-GASTC-3'. The kinetic parameters of methylation reaction have been determined. The catalytic constant--2.2 min(-1), the Michaelis constant on T7 DNA--9.8 nM and on SAM--5.8 microM.
嗜热脂肪芽孢杆菌SE-589（识别位点5'-GAGTC-3'）的切口酶修饰系统操纵子包含两个DNA甲基转移酶基因：bstSEIM1和bstSEIM2。编码DNA甲基转移酶M2.BstSEI的基因被克隆到pJW载体中并在大肠杆菌细胞中表达。酶M2.BstSEI已通过色谱纯化分离出来。M2.BstSEI在55摄氏度和pH 7.5时表现出最大活性。该酶修饰DNA序列5'-GAGTC-3'中的腺嘌呤，底物特异性为5'-GASTC-3'。已确定甲基化反应的动力学参数。催化常数为2.2 min⁻¹，对T7 DNA的米氏常数为9.8 nM，对SAM的米氏常数为5.8 μM。
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