Lavysh Daria, Sokolova Maria, Minakhin Leonid, Yakunina Maria, Artamonova Tatjana, Kozyavkin Sergei, Makarova Kira S, Koonin Eugene V, Severinov Konstantin
Institute of Molecular Genetics and Gene Biology, Russian Academy of Sciences, Moscow, Russia.
Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russia; Skolkovo Institute of Science and Technology, Skolkovo, Russia.
Virology. 2016 Aug;495:185-96. doi: 10.1016/j.virol.2016.04.030. Epub 2016 May 26.
Bacteriophage AR9 and its close relative PBS1 have been extensively used to construct early Bacillus subtilis genetic maps. Here, we present the 251,042bp AR9 genome, a linear, terminally redundant double-stranded DNA containing deoxyuridine instead of thymine. Multiple AR9 genes are interrupted by non-coding sequences or sequences encoding putative endonucleases. We show that these sequences are group I and group II self-splicing introns. Eight AR9 proteins are homologous to fragments of bacterial RNA polymerase (RNAP) subunits β/β'. These proteins comprise two sets of paralogs of RNAP largest subunits, with each paralog encoded by two disjoint phage genes. Thus, AR9 is a phiKZ-related giant phage that relies on two multisubunit viral RNAPs to transcribe its genome independently of host transcription apparatus. Purification of one of PBS1/AR9 RNAPs has been reported previously, which makes AR9 a promising object for further studies of RNAP evolution, assembly and mechanism.
噬菌体AR9及其近亲PBS1已被广泛用于构建早期枯草芽孢杆菌的遗传图谱。在此，我们展示了251,042bp的AR9基因组，这是一种线性、末端冗余的双链DNA，其中含有脱氧尿苷而非胸腺嘧啶。多个AR9基因被非编码序列或编码假定核酸内切酶的序列打断。我们发现这些序列是I组和II组自我剪接内含子。八个AR9蛋白与细菌RNA聚合酶（RNAP）亚基β/β'的片段同源。这些蛋白包括两组RNAP最大亚基的旁系同源物，每个旁系同源物由两个不连续的噬菌体基因编码。因此，AR9是一种与phiKZ相关的巨型噬菌体，它依赖于两个多亚基病毒RNAP来独立于宿主转录装置转录其基因组。之前已有报道纯化了PBS1/AR9 RNAP中的一种，这使得AR9成为进一步研究RNAP进化、组装和机制的一个有前景的对象。
