Proteomic survey of the DNA damage response inCaulobacter crescentus

Abstract

The bacterial DNA damage response is a critical, coordinated response to DNA replication stress. The canonical bacterial DNA damage response, first characterized in Escherichia coli, is controlled by the global transcriptional regulator LexA and the recombinase RecA. While genome-wide studies have described how the DNA damage response is regulated at a transcriptional level, relatively little is known about post-transcriptional regulation of this response. Here, we perform a proteome-wide survey of the DNA damage response in Caulobacter crescentus. We find that not all changes in protein abundance during the response to DNA damage are predicted by changes in transcription. We validate one of these post-transcriptionally regulated candidates to show its importance to survival of DNA damage. To investigate post-translational control of the DNA damage response, we perform a similar survey in cells lacking the Lon protease. This reveals that induction of the DNA damage response at the protein level is dampened in these strains, consistent with their reduced tolerance to DNA damage. Finally, proteome-wide stability measurements following damage nominate candidate Lon substrates that suggest post-translational regulation of the DNA damage response. The DNA damage response helps bacteria to respond to and potentially survive DNA damage. The mutagenesis that is induced as part of this response plays a role in bacterial evolution and is essential to the development and spread of antibiotic resistance. Understanding how bacteria coordinate their response to DNA damage could help us to combat this growing threat to human health. While the transcriptional regulation of the bacterial DNA damage response has been characterized, this study is the first to our knowledge to compare changes in RNA and protein levels to identify potential targets of post-transcriptional regulation in response to DNA damage.