Theil E C, Forsyth G W, Jones E E
J Bacteriol. 1969 Jul;99(1):269-73. doi: 10.1128/jb.99.1.269-273.1969.
Effect of the M (modifier) gene of Escherichia coli W on the expression of wild-type structural genes of four arginine biosynthetic enzymes was studied by examining enzyme activity in cell-free extracts of cultures grown in minimal medium and medium containing arginine. The mutant M gene was originally identified as causing arginine-induced synthesis of acetylornithine delta-transaminase in a strain deficient for the enzyme. The strains used in this study received the mutant M gene by recombination. Noncoordinate repression has been demonstrated for two more enzymes of the arginine regulon of E. coli W and the M(-) gene increases the degree of noncoordinate repression for the regulon. Mutation of the M gene results in altered regulation of acetylornithine delta-transaminase, ornithine transcarbamylase, and acetylornithinase. In addition, a decreased growth rate is observed. It is proposed that the M gene is a regulatory gene. A model is presented to explain the data which involves changes in operator-repressor affinity for the structural genes and possibly for the gene controlling arginyl transfer ribonucleic acid synthetase.
通过检测在基本培养基和含精氨酸培养基中生长的培养物的无细胞提取物中的酶活性，研究了大肠杆菌W的M（修饰）基因对四种精氨酸生物合成酶野生型结构基因表达的影响。突变的M基因最初被鉴定为在一种缺乏该酶的菌株中导致精氨酸诱导的乙酰鸟氨酸δ-转氨酶合成。本研究中使用的菌株通过重组获得了突变的M基因。已经证明大肠杆菌W精氨酸调节子的另外两种酶存在非协同阻遏，并且M（-）基因增加了该调节子的非协同阻遏程度。M基因的突变导致乙酰鸟氨酸δ-转氨酶、鸟氨酸转氨甲酰酶和乙酰鸟氨酸酶的调节改变。此外，观察到生长速率下降。有人提出M基因是一个调节基因。提出了一个模型来解释这些数据，该模型涉及操纵子-阻遏物对结构基因以及可能对控制精氨酰转移核糖核酸合成酶的基因的亲和力变化。
