Clamping down on transcription: repression of archaeal RNAP by the novel viral regulator RIP

Little is known about how archaeal viruses perturbate the transcription machinery of their hosts. We provide the first example of a non-DNA binding archaeo-viral transcription factor that directly targets the host RNA polymerase and efficiently represses its activity. We have used cross-linking and mass spectrometry to identify how ORF145 binds in the DNA-binding channel of RNA polymerase.