Homologs of the Escherichia coli F Element Protein TraR, Including Phage Lambda Orf73, Directly Reprogram Host Transcription.
Homologs of the Escherichia coli F Element Protein TraR, Including Phage Lambda Orf73, Directly Reprogram Host Transcription.
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DOI：
10.1128/mbio.00952-22
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发表时间：
2022-06-28
期刊：
影响因子：
6.4
通讯作者：
Gourse, Richard L.
中科院分区：
文献类型：
--
作者：
Gopalkrishnan, Saumya;Ross, Wilma;Akbari, Madeline S.;Li, Xintian;Haycocks, James R. J.;Grainger, David C.;Court, Donald L.;Gourse, Richard L.
细菌细胞及其相关的质粒和噬菌体编码许多功能未知的小蛋白质。例如，73个氨基酸的蛋白质TraR由大肠杆菌接合F质粒的转移操纵子编码。TraR是DksA的远亲同源物，DksA是一种在几乎所有变形菌物种中发现的蛋白质，其是ppGpp在严格响应期间调节转录所需的。TraR和DksA通过直接与RNA聚合酶结合而不与DNA结合来增加或减少转录起始，这取决于启动子的动力学特征。与DksA不同，其完全活性需要ppGpp作为辅因子，TraR本身完全活跃，不受ppGpp的影响。TraR属于由蛋白细菌噬菌体和其他移动的元件编码的不同蛋白质家族。在这里，我们通过实验解决了TraR家族的其他成员是否像F元素编码的TraR一样发挥作用。纯化的TraR和所有5个同源物，检查绑定到RNA聚合酶，功能在较低的浓度比DksA，并补充了dksA-空菌株的基本培养基上的生长。其中一个同源物λ Orf 73，由λ噬菌体编码，被更详细地检查。λ Orf 73减缓宿主生长并增加噬菌体爆发大小。突变分析表明，λ Orf 73和TraR具有相似的抑制rRNA和r蛋白启动子的机制。我们认为TraR及其同源物调节宿主转录，以转移细胞资源到噬菌体繁殖或接合，而不诱导ppGpp和严格的反应。
Bacterial cells and their associated plasmids and bacteriophages encode numerous small proteins of unknown function. One example, the 73-amino-acid protein TraR, is encoded by the transfer operon of the conjugative F plasmid of Escherichia coli. TraR is a distant homolog of DksA, a protein found in almost all proteobacterial species that is required for ppGpp to regulate transcription during the stringent response. TraR and DksA increase or decrease transcription initiation depending on the kinetic features of the promoter by binding directly to RNA polymerase without binding to DNA. Unlike DksA, whose full activity requires ppGpp as a cofactor, TraR is fully active by itself and unaffected by ppGpp. TraR belongs to a family of divergent proteins encoded by proteobacterial bacteriophages and other mobile elements. Here, we experimentally addressed whether other members of the TraR family function like the F element-encoded TraR. Purified TraR and all 5 homologs that were examined bound to RNA polymerase, functioned at lower concentrations than DksA, and complemented a dksA-null strain for growth on minimal medium. One of the homologs, λ Orf73, encoded by bacteriophage lambda, was examined in greater detail. λ Orf73 slowed host growth and increased phage burst size. Mutational analysis suggested that λ Orf73 and TraR have a similar mechanism for inhibiting rRNA and r-protein promoters. We suggest that TraR and its homologs regulate host transcription to divert cellular resources to phage propagation or conjugation without induction of ppGpp and a stringent response.
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DOI：
10.1073/pnas.121164898
发表时间：
2001-06-05
影响因子：
11.1
作者：
Ellis, HM;Yu, DG;Court, DL
通讯作者：
Court, DL
影响因子：
16
作者：
Chen, James;Chiu, Courtney;Darst, Seth A.
通讯作者：
Darst, Seth A.
影响因子：
3.2
作者：
Hemm, Matthew R.;Paul, Brian J.;Storz, Gisela
通讯作者：
Storz, Gisela
影响因子：
3.5
作者：
Iyer, LM;Koonin, EV;Aravind, L
通讯作者：
Aravind, L
影响因子：
10.5
作者：
Gourse RL;Chen AY;Gopalkrishnan S;Sanchez-Vazquez P;Myers A;Ross W
通讯作者：
Ross W