Pasternak A O, van den Born E, Spaan W J, Snijder E J
Molecular Virology Laboratory, Department of Medical Microbiology, Center of Infectious Diseases, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands.
EMBO J. 2001 Dec 17;20(24):7220-8. doi: 10.1093/emboj/20.24.7220.
Nidovirus subgenomic mRNAs contain a leader sequence derived from the 5' end of the genome fused to different sequences ('bodies') derived from the 3' end. Their generation involves a unique mechanism of discontinuous subgenomic RNA synthesis that resembles copy-choice RNA recombination. During this process, the nascent RNA strand is transferred from one site in the template to another, during either plus or minus strand synthesis, to yield subgenomic RNA molecules. Central to this process are transcription-regulating sequences (TRSs), which are present at both template sites and ensure the fidelity of strand transfer. Here we present results of a comprehensive co-variation mutagenesis study of equine arteritis virus TRSs, demonstrating that discontinuous RNA synthesis depends not only on base pairing between sense leader TRS and antisense body TRS, but also on the primary sequence of the body TRS. While the leader TRS merely plays a targeting role for strand transfer, the body TRS fulfils multiple functions. The sequences of mRNA leader-body junctions of TRS mutants strongly suggested that the discontinuous step occurs during minus strand synthesis.
尼多病毒亚基因组mRNA包含一个源自基因组5'端的前导序列，该序列与源自3'端的不同序列（“主体”）融合。它们的产生涉及一种独特的不连续亚基因组RNA合成机制，类似于拷贝选择RNA重组。在这个过程中，新生的RNA链在正链或负链合成期间从模板中的一个位点转移到另一个位点，以产生亚基因组RNA分子。这个过程的核心是转录调控序列（TRS），它存在于两个模板位点并确保链转移的保真度。在这里，我们展示了对马动脉炎病毒TRS进行全面共变诱变研究的结果，证明不连续RNA合成不仅取决于正义前导TRS与反义主体TRS之间的碱基配对，还取决于主体TRS的一级序列。虽然前导TRS仅在链转移中起靶向作用，但主体TRS具有多种功能。TRS突变体的mRNA前导-主体连接序列强烈表明不连续步骤发生在负链合成期间。
