Mechanisms of Poxviral Gene Expression Revealed

A team of researchers from the Biocenter of the Julius-Maximilian University of Würzburg has now shared an atomic picture of the polymerases of vaccinia viruses. The results of their work were published in Nature Structure and Molecular Biology.

“We have mixed isolated RNA polymerase with a piece of DNA containing the promoter, i.e. the start signal for the transcription of viral genes. The enzyme recognized precisely this DNA element and started producing mRNA,” explains Julia Bartuli. 

Next, the samples were examined via cryo-electron microscopy. The scientists were then able to reconstruct the three-dimensional structure of the sample down to the atomic scale, using modern computerized methods. “One single sample we examined in the microscope allowed us to reconstruct a total of six different polymerase complexes, which we could finally allocate to individual phases of the transcription process,” says Clemens Grimm. “We can string the individual pictures together as in a movie and thus represent the early transcription phase with time resolution.”

About the relevance of the findings, lead researcher Utz Fischer concluded that “There is still no reliable cure for smallpox infection, it can only be prevented by vaccination. If the still existing virus samples were to be spread again, for example by a terrorist attack, they would hit a population that has no immunization.”