Escherichia coli lac operator mRNA affects translation initiation of β-galactosidase mRNA
Escherichia coli lac operator mRNA affects translation initiation of β-galactosidase mRNA
复制标题
大肠杆菌 lac 操纵子 mRNA 影响 β-半乳糖苷酶 mRNA 的翻译起始
作者：
V. J. Cannistraro;D. Kennell
消息开头(特定多肽的mRNA)的主要功能是确保翻译的正确启动。人们对决定翻译频率的因素知之甚少，也不知道它的可变性在基因总表达中是否重要。最近，一项允许计算体内频率的分析被引入；它表明lac mRNA的第一条和最后一条信息在体内的起始率相差五倍1。至少部分地，起始AUG密码子上游约8-15个残基的三个或更多核苷酸序列可以影响不同的启动频率，该序列与16S核糖体RNA2，3末端的富嘌呤序列互补。4个这样的互补核苷酸是β-半乳糖苷酶(EC 3.2.1.23，βGase)消息8月开始之前的第8-11残基。目前还没有针对该序列的突变体，但有一个更远的区域的完整系列--8月之前的22到34个核苷酸：乳清蛋白突变体。在这里，我们展示了这些突变中的某些会影响翻译的速度以及该消息的稳定性。
THE primary function of the start of a message (mRNA for a specific polypeptide) is to ensure the correct initiation of translation. Little is known about the factors determining the frequency of translation or indeed if its variability is important in the total expression of genes. Recently, an analysis was introduced that allows calculation of in vivo frequencies; it was shown that the in vivo initiation rates of the first and last messages of the lac mRNA differ by fivefold1. Different initiation frequencies could be effected, in part at least, by a sequence of three or more nucleotides about 8 to 15 residues upstream from the initiating AUG codon that is complementary to a purine-rich sequence at the end of the 16S ribosomal RNA2,3. Four such complementary nucleotides are residues 8–11 before the AUG start of the β-galactosidase (EC 3.2.1.23, βGase) message. Mutants for this sequence are not available, but there is a whole series for a more distant region—22 to 34 nucleotides before the AUG: the lac Oc mutants. Here we show that certain of these mutations affect the rate of translation as well as the stability of this message.