Filamentation in protein repair-deficient Escherichia coli

Christina Kadine Carstens


In Escherichia coli, PCM is an enzyme that repairs spontaneous isoaspartyl damage to proteins. Preliminary data suggest that under stressful conditions, particularly low salt and oxidative stress, pcm-deletion mutants undergo filamentation. Filamentation is the elongation of cells during replication, instead of their physical division. We found both under no stress and oxidative stress conditions, that pcm-deletion mutants showed a higher rate of filamentation compared to wild-type. Cell division in E. coli can be inhibited by the induction of the sulA gene. SulA is associated with the SOS regulatory system, which responds to DNA damage by arresting the cell cycle to allow for the response of DNA repair factors. We hypothesized that sulA-deletion mutants under oxidative stress would show a decrease in filamentation relative to wild-type and that the lack of the pcm and sulA genes would result in a change in the amount of filamentation relative to the pcm-deletion mutant. We found that both sulA- and sulA- pcm-deletion mutants showed a decrease in filamentation relative to wild-type and pcm-deletion mutants, both under no stress and oxidative stress conditions. These results indicate that filamentation may not only occur by a SulA-dependent mechanism, but by a SulA-independent mechanism.


Protein repair; filamentation; oxidative stress

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