Inhibiting translation elongation can aid genome duplication in Escherichia coli.
Inhibiting translation elongation can aid genome duplication in Escherichia coli.
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DOI：
10.1093/nar/gkw1254
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发表时间：
2017-03-17
影响因子：
14.9
通讯作者：
McGlynn P
中科院分区：
文献类型：
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作者：
Myka KK;Hawkins M;Syeda AH;Gupta MK;Meharg C;Dillingham MS;Savery NJ;Lloyd RG;McGlynn P
复制和转录之间的冲突挑战染色体复制。Rep和UvrD辅助解旋酶可促进大肠杆菌复制体沿转录DNA的沿着移动，其中Δrep ΔuvrD细胞在快速生长条件下不可存活。我们已经发现，tRNA基因aspT、氨酰tRNA合成酶AspRS和脯氨酸-脯氨酸键形成所需的翻译因子EF-P的突变抑制了Δrep ΔuvrD致死性。因此，复制-转录冲突可以通过部分牺牲减少复制障碍的机制来缓解，即翻译减少RNA聚合酶回溯的核糖体。抑制依赖于RelA指导的（p）ppGpp的合成，（p）ppGpp是一种减少复制-转录冲突的信号分子，RelA激活需要核糖体暂停。这些抑制子中的（p）ppGpp水平也与Rho活性的需要负相关，Rho活性是一种RNA移位酶，可以结合新出现的转录物并置换转录复合物。这些数据说明了促进基因表达和基因组复制的不同机制之间的良好平衡，并表明辅助解旋酶是这种平衡的主要决定因素。这种平衡对细菌存活的其他方面也至关重要：这里鉴定的突变增加了持久性，表明在面临抗生素挑战的天然细菌群体中可能会出现类似的突变。
Conflicts between replication and transcription challenge chromosome duplication. Escherichia coli replisome movement along transcribed DNA is promoted by Rep and UvrD accessory helicases with Δrep ΔuvrD cells being inviable under rapid growth conditions. We have discovered that mutations in a tRNA gene, aspT, in an aminoacyl tRNA synthetase, AspRS, and in a translation factor needed for efficient proline–proline bond formation, EF-P, suppress Δrep ΔuvrD lethality. Thus replication-transcription conflicts can be alleviated by the partial sacrifice of a mechanism that reduces replicative barriers, namely translating ribosomes that reduce RNA polymerase backtracking. Suppression depends on RelA-directed synthesis of (p)ppGpp, a signalling molecule that reduces replication-transcription conflicts, with RelA activation requiring ribosomal pausing. Levels of (p)ppGpp in these suppressors also correlate inversely with the need for Rho activity, an RNA translocase that can bind to emerging transcripts and displace transcription complexes. These data illustrate the fine balance between different mechanisms in facilitating gene expression and genome duplication and demonstrate that accessory helicases are a major determinant of this balance. This balance is also critical for other aspects of bacterial survival: the mutations identified here increase persistence indicating that similar mutations could arise in naturally occurring bacterial populations facing antibiotic challenge.