A family of anti-sigma70 proteins in T4-type phages and bacteria that are similar to AsiA, a Transcription inhibitor and co-activator of bacteriophage T4.
A family of anti-sigma70 proteins in T4-type phages and bacteria that are similar to AsiA, a Transcription inhibitor and co-activator of bacteriophage T4.
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T4 型噬菌体和细菌中的一个抗 sigma70 蛋白家族，与 AsiA 类似，AsiA 是噬菌体 T4 的转录抑制剂和共激活剂。
DOI：
10.1016/j.jmb.2004.10.003
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发表时间：
2004
影响因子：
5.6
通讯作者：
Hinton,DeborahM
中科院分区：
文献类型：
--
作者：
Pineda,Melissa;Gregory,BrianD;Szczypinski,Bridget;Baxter,KimberlyR;Hochschild,Ann;Miller,EricS;Hinton,DeborahM
抗σ70因子与原核生物σ聚合酶的特异亚单位RNA70蛋白相互作用。噬菌体T4抗σ70蛋白，亚洲，与大肠杆菌σ70亚基的第4.1和4.2区域紧密结合，并抑制σ70启动子的转录，这需要识别规范的σ70−35DNA序列。在T4转录激活子MOTA的存在下，亚洲也起到T4中间启动子转录的共同激活作用，T4中间启动子保留了典型的σ70−10共识序列，但具有以−30为中心的MoTA盒序列，而不是σ70−35序列。大肠杆菌抗σ70蛋白Rsd还与σ70的第4.2区相互作用，并抑制σ70启动子的转录。我们对T4Asia和Rsd，与预测的T4型噬菌体RB69，44RR，KVP40和Aeh1的亚洲同源序列，以及与铜绿假单胞菌藻酸盐生产调节因子Alq的序列比较表明，这些蛋白在已知对T4 Asia与σ70区域4结合的重要位置共享保守的氨基酸残基。我们表明，像T4 Asia一样，RSD在天然蛋白凝胶中与σ70结合，并且，与T4 Asia一样，RSD中的L18S替换破坏了这一复合体。先前的工作已将4.1区内的σ70氨基酸F563指定为亚洲结合的关键决定因素。该残基还参与了σ70与核心的β-Float的结合，表明ASIA通过破坏σ704.1区域与β-Float之间的相互作用而抑制转录。我们发现，与T4 ASIA一样，KVP40 ASIA、RSD或ALQ与σ70第4区的相互作用因F563Y替换而减弱。我们还证明，与T4亚洲和RSD一样，KVP40亚洲抑制依赖于σ70的启动子的转录。我们推测，亚洲噬菌体同源基因、RSD和ALQ是T4型噬菌体和细菌相关家族的成员，它们与主要σ因子的作用相似。此外，我们还发现，尽管在KVP40基因组中没有明确的MoTA同源基因，并且噬菌体基因组似乎缺乏典型的中间启动子序列，但KVP40亚洲在T4 MoTA存在的情况下激活了T4中间启动子的转录。我们推测KVP40编码的蛋白质在序列上与T4MoTA不同，但功能相同。
Anti-σ70factors interact with σ70proteins, the specificity subunits of prokaryotic RNA polymerase. The bacteriophage T4 anti-σ70protein, AsiA, binds tightly to regions 4.1 and 4.2 of the σ70subunit of Escherichia coli RNA polymerase and inhibits transcription from σ70promoters that require recognition of the canonical σ70−35 DNA sequence. In the presence of the T4 transcription activator MotA, AsiA also functions as a co-activator of transcription from T4 middle promoters, which retain the canonical σ70−10 consensus sequence but have a MotA box sequence centered at −30 rather than the σ70−35 sequence. The E.coli anti-σ70protein Rsd also interacts with region 4.2 of σ70and inhibits transcription from σ70promoters. Our sequence comparisons of T4 AsiA with Rsd, with the predicted AsiA orthologs of the T4-type phages RB69, 44RR, KVP40, and Aeh1, and with AlgQ, a regulator of alginate production in Pseudomonas aeruginosa indicate that these proteins share conserved amino acid residues at positions known to be important for the binding of T4 AsiA to σ70region 4. We show that, like T4 AsiA, Rsd binds to σ70in a native protein gel and, as with T4 AsiA, a L18S substitution in Rsd disrupts this complex. Previous work has assigned σ70amino acid F563, within region 4.1, as a critical determinant for AsiA binding. This residue is also involved in the binding of σ70to the β-flap of core, suggesting that AsiA inhibits transcription by disrupting the interaction between σ70region 4.1 and the β-flap. We find that as with T4 AsiA, the interaction of KVP40 AsiA, Rsd, or AlgQ with σ70region 4 is diminished by the substitution F563Y. We also demonstrate that like T4 AsiA and Rsd, KVP40 AsiA inhibits transcription from σ70-dependent promoters. We speculate that the phage AsiA orthologs, Rsd, and AlgQ are members of a related family in T4-type phage and bacteria, which interact similarly with primary σ factors. In addition, we show that even though a clear MotA ortholog has not been identified in the KVP40 genome and the phage genome appears to lack typical middle promoter sequences, KVP40 AsiA activates transcription from T4 middle promoters in the presence of T4 MotA. We speculate that KVP40 encodes a protein that is dissimilar in sequence, but functionally equivalent, to T4 MotA.