Institute of Virology, Philipps-University Marburg, Marburg, Germany.
J Virol. 2024 Sep 17;98(9):e0104724. doi: 10.1128/jvi.01047-24. Epub 2024 Aug 28.
Little is known regarding the molecular mechanisms that highly pathogenic Marburg virus (MARV) utilizes to transcribe and replicate its genome. Previous studies assumed that dephosphorylation of the filoviral transcription factor VP30 supports transcription, while phosphorylated VP30 reduces transcription. Here, we focused on the role of the host protein phosphatase 2A (PP2A) for VP30 dephosphorylation and promotion of viral transcription. We could show that MARV NP interacts with the subunit B56 of PP2A, as previously shown for the Ebola virus, and that this interaction is important for MARV transcription activity. Inhibition of the interaction between PP2A and NP either by mutating the B56 binding motif encoded on NP, or the use of a PP2A inhibitor, induced VP30 hyperphosphorylation, and as a consequence a decrease of MARV transcription as well as viral growth. These results suggest that NP plays a key role in the dephosphorylation of VP30 by recruiting PP2A. Generation of recombinant (rec) MARV lacking the PP2A-B56 interaction motif on NP was not possible suggesting an essential role of PP2A-mediated VP30 dephosphorylation for the MARV replication cycle. Likewise, we were not able to generate recMARV containing VP30 phosphomimetic mutants indicating that dynamic cycles of VP30 de- and rephosphorylation are a prerequisite for an efficient viral life cycle. As the specific binding motifs of PP2A-B56 and VP30 within NP are highly conserved among the filoviral family, our data suggest a conserved mechanism for filovirus VP30 dephosphorylation by PP2A, revealing the host factor PP2A as a promising target for pan-filoviral therapies.
Our study elucidates the crucial role of host protein phosphatase 2A (PP2A) in Marburg virus (MARV) transcription. The regulatory subunit B56 of PP2A facilitates VP30 dephosphorylation, and hence transcription activation, via binding to NP. Our results, together with previous data, reveal a conserved mechanism of filovirus VP30 dephosphorylation by host factor PP2A at the NP interface and provide novel insights into potential pan-filovirus therapies.
关于高致病性马尔堡病毒（MARV）利用何种分子机制进行转录和复制其基因组，目前知之甚少。先前的研究假设丝状病毒转录因子 VP30 的去磷酸化有助于转录，而磷酸化的 VP30 则会降低转录。在这里，我们专注于宿主蛋白磷酸酶 2A（PP2A）在 VP30 去磷酸化和促进病毒转录中的作用。我们可以证明 MARV NP 与 PP2A 的亚基 B56 相互作用，正如先前在埃博拉病毒中所显示的那样，这种相互作用对于 MARV 转录活性很重要。通过突变 NP 上编码的 B56 结合基序或使用 PP2A 抑制剂来抑制 PP2A 和 NP 之间的相互作用，会诱导 VP30 过度磷酸化，从而导致 MARV 转录以及病毒生长减少。这些结果表明，NP 通过招募 PP2A 在 VP30 的去磷酸化中起关键作用。生成缺乏 NP 上 PP2A-B56 相互作用基序的重组（rec）MARV 是不可能的，这表明 PP2A 介导的 VP30 去磷酸化对于 MARV 复制周期至关重要。同样，我们也无法生成包含 VP30 磷酸模拟突变体的 recMARV，这表明 VP30 的去磷酸化和再磷酸化的动态循环是有效病毒生命周期的前提。由于丝状病毒家族中 NP 内的 PP2A-B56 和 VP30 的特定结合基序高度保守，我们的数据表明 PP2A 对丝状病毒 VP30 去磷酸化具有保守机制，揭示了宿主因子 PP2A 是泛丝状病毒治疗的有希望的靶标。
我们的研究阐明了宿主蛋白磷酸酶 2A（PP2A）在马尔堡病毒（MARV）转录中的关键作用。PP2A 的调节亚基 B56 通过与 NP 结合促进 VP30 的去磷酸化，从而激活转录。我们的结果与先前的数据一起揭示了丝状病毒 VP30 在 NP 界面处通过宿主因子 PP2A 去磷酸化的保守机制，并为潜在的泛丝状病毒治疗提供了新的见解。
