Inactivation of the RluD Pseudouridine Synthase Has Minimal Effects on Growth and Ribosome Function in Wild-Type Escherichia coli and Salmonella enterica
Inactivation of the RluD Pseudouridine Synthase Has Minimal Effects on Growth and Ribosome Function in Wild-Type Escherichia coli and Salmonella enterica
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DOI：
10.1128/jb.00970-10
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发表时间：
2011-01-01
影响因子：
3.2
通讯作者：
Gregory, Steven T.
中科院分区：
文献类型：
--
作者：
O'Connor, Michael;Gregory, Steven T.
大肠杆菌rud基因编码一种伪尿嘧啶合成酶，负责在23S rRNA的螺旋69的1911、1915和1917位置上进行伪尿嘧啶（Psi）修饰。据报道，大肠杆菌K-12菌株中rluD的缺失与生长极慢、终止密码子的读透增加以及50S核糖体亚基组装和30S-50S亚基结合缺陷有关。编码释放因子2 （RF2）和RF3的prfB和prfC基因中的抑制突变现已被分离出来，这些基因可以恢复野生型生长速率并纠正核糖体缺陷。这些抑制子将螺旋69 Psi残基与蛋白质合成的终止相连接。然而，本文报道的进一步遗传分析也表明，大肠杆菌K-12菌株中与rluD失活相关的生长缓慢和其他缺陷是由于RF2蛋白缺陷造成的，该蛋白在246位有苏氨酸，这在所有K-12菌株中都存在。这与大多数细菌RF2s中在这个位置发现的更典型的丙氨酸形成对比，包括其他大肠杆菌菌株。含有来自大肠杆菌B的prfB等位基因的大肠杆菌菌株或肠沙门氏菌中的rluD失活，都携带带有Ala246的RF2，对生长、终止或核糖体功能的影响微不足道。结果表明，与野生细菌相比，携带部分缺陷RF2蛋白的大肠杆菌K-12菌株的终止功能特别容易受到核糖体- rf相互作用的干扰，例如h69 Psi修饰的丢失。
The Escherichia coli rluD gene encodes a pseudouridine synthase responsible for the pseudouridine (Psi) modifications at positions 1911, 1915, and 1917 in helix 69 of 23S rRNA. It has been reported that deletion of rluD in K-12 strains of E. coli is associated with extremely slow growth, increased readthrough of stop codons, and defects in 50S ribosomal subunit assembly and 30S-50S subunit association. Suppressor mutations in the prfB and prfC genes encoding release factor 2 (RF2) and RF3 that restore the wild type-growth rate and also correct the ribosomal defects have now been isolated. These suppressors link helix 69 Psi residues with the termination phase of protein synthesis. However, further genetic analysis reported here also reveals that the slow growth and other defects associated with inactivation of rluD in E. coli K-12 strains are due to a defective RF2 protein, with a threonine at position 246, which is present in all K-12 strains. This is in contrast to the more typical alanine found at this position in most bacterial RF2s, including those of other E. coli strains. Inactivation of rluD in E. coli strains containing the prfB allele from E. coli B or in Salmonella enterica, both carrying an RF2 with Ala246, has negligible effects on growth, termination, or ribosome function. The results indicate that, in contrast to those in wild bacteria, termination functions in E. coli K-12 strains carrying a partially defective RF2 protein are especially susceptible to perturbation of ribosome-RF interactions, such as that caused by loss of h69 Psi modifications.