Many key activities in living organisms rely on complex molecular machines composed of assemblies of proteins that work together to achieve a defined output. One such machine, termed RNA polymerase (RNAP) plays a crucial role in gene expression. Appropriate regulation and co-ordination of gene expression is important in all living organisms, from bacteria to humans.
Gene expression occurs when the RNAP reads a DNA sequence to create a "messenger" molecule that acts as a template for protein synthesis. This part of gene expression is known as transcription. I studied how RNAP is controlled by an other molecular machine, an AAA+ protein called PspF. The AAA+ protein family is present in all three kingdom of life. Proteins from this family all use a common energetical molecule (called ATP) present in the cell to produce different specific activities. Because of the broad spectrum of activities, these proteins can be implicated in bacterial pathogenicity or in human diseases. By using the bacterial AAA+ protein model, the aim of my project was to enhance our understanding of how the AAA+ protein could control the activity of RNAP.
Using a combined biochemical and structural approach, I discovered how the protein uses the energy (ATP) of the cell to do work. I uncovered how ATP interacts with the AAA+ protein, changes its functionality, and so can lead to productive transcription.