Poster Presentation Melbourne Protein Group Student Symposium 2013

Elucidating the molecular details of RssB-mediated turnover of SigmaS by the AAA+ protease, ClpXP (#88)

Jessica E Zammit 1 , James Micevski 1 , Kaye N Truscott 1 , David A Dougan
  1. La Trobe Institute for Molecular Science, Melbourne, VIC, Australia

The general stress response provides a pathway for bacteria to survive in response to a range of different environmental stresses. This pathway is largely controlled at the post-translational level through the regulated degradation of the transcription factor, SigmaS (σS). Under normal conditions, the phosphorylated adaptor protein RssB recognises σS and delivers it to the ClpXP protease where it is rapidly degraded. In contrast, under conditions of “general” stress the turnover of σS is inhibited by a number of stress-specific anti-adaptors, which as the name suggests inhibit the activity of the adaptor protein, RssB. Currently however, the molecular details of each step is poorly defined. Here we describe our current understanding of the molecular details of this process. To date, we have identified, using a range of biochemical assays, that the N-terminal region of σS is crucial for ClpX recognition, but not for binding to RssB. Likewise we are currently examining the molecular details of the interaction between RssB and the DNA-damage induced anti-adaptor protein, IraD. Collectively, these data improve our mechanistic understanding of σS turnover and the general stress response.