McCarthy J E, Bokelmann C
Division of Microbiology, GBF, Gesellschaft für Biotechnologische Forschung mbH, Braunschweig, FRG.
Mol Microbiol. 1988 Jul;2(4):455-65. doi: 10.1111/j.1365-2958.1988.tb00051.x.
Transcription and translation of the atp genes encoding the subunits b, delta, alpha, gamma and epsilon of the Escherichia coli H+-ATPase were studied. The nature and quantities of the respective transcripts initiated from different promoters were compared with overall expression rates thus yielding accurate information about relative translational efficiency and its coupling to mRNA levels. Part of the highly efficient subunit c gene translational initiation region (TIR) was used as a tool in manipulating the TIRs of the other genes. Rate control of atp cistron translation occurs at the initiation level and is determined locally by each gene's TIR. In this way, individual subunit synthesis rates are set to match the requirements for H+-ATPase assembly. There is no (or very restricted) translational coupling between the cistrons. Translational initiation rates of the normally weakly expressed atp genes could be increased by up to a factor of 27 by manipulating the sequences upstream of the start codons, despite biased codon usages. In the presence of an improved upstream sequence, the N-terminal sequence of the subunit gamma gene exerted a limiting effect. This could be relieved by altering the sequence of the first seven codons. The levels of subunit gamma mRNA were more sensitive to changes in translational efficiency than the concentrations of the other atp mRNAs. The relationships between initiation efficiency and primary and secondary structure in the natural and manipulated atp TIRs are discussed in detail.
对编码大肠杆菌H⁺-ATP酶亚基b、δ、α、γ和ε的atp基因的转录和翻译进行了研究。将从不同启动子起始的各自转录本的性质和数量与整体表达率进行比较，从而得出有关相对翻译效率及其与mRNA水平耦合的准确信息。高效的亚基c基因翻译起始区域（TIR）的一部分被用作操纵其他基因TIR的工具。atp顺反子翻译的速率控制发生在起始水平，并且由每个基因的TIR局部决定。通过这种方式，各个亚基的合成速率被设定为与H⁺-ATP酶组装的需求相匹配。顺反子之间不存在（或非常有限的）翻译偶联。尽管密码子使用存在偏好，但通过操纵起始密码子上游的序列，正常弱表达的atp基因的翻译起始速率可提高多达27倍。在存在改进的上游序列的情况下，亚基γ基因的N端序列发挥了限制作用。这可以通过改变前七个密码子序列来缓解。亚基γ mRNA的水平比其他atp mRNA的浓度对翻译效率变化更敏感。详细讨论了天然和操纵的atp TIR中起始效率与一级和二级结构之间的关系。
