Structural plasticity of T4 transcription co-activator gp33 revealed by a protease-resistant unfolded state

摘要: Gene 33 protein (gp33) is a transcriptional coactivator for late genes of the T4 bacteriophage. gp33 possesses 5-helix bundle core, with unstructured N- and C-terminal regions that account >50% sequence. It plays unique role interacting host RNA polymerase, couples transcription DNA replication, dual function as repressor co-activator in phage transcription. Here, we identify structural plasticity molecular basis nature gp33. We find has peculiar property remaining protease insensitive its urea-unfolded state. Using NMR studies spectroscopic measurements, propose intra-protein interactions are replaced by protein-urea This process not only unfolds but also renders it protease-resistant. Our shed new light on malleability might be important transition from to co-activator.