Abstract
The chi subunit, encoded by the holC gene, is known to have a significant role in the efficient replication of DNA. It is unknown whether chi has other functions in the cell and it was the goal of this study to elucidate interaction of chi with other proteins. I screened suppressor mutations for a ΔholC Escherichia coli strain to determine what genes may be linked to chi function. Suppression of ΔholC mutants was done by culturing the strain in unrestricted growth and replicative stress conditions by exposure to AZT. Colonies that were larger in size relative to others were identified as suppressors and measured for viability and sensitivity to AZT. A total of 79 suppressor colonies were isolated. Many suppressors had greater viability and resistance to AZT relative to ΔholC mutants. Furthermore, suppressors had morphological changes including elongation of the cell and development of a mucoid membrane. These observations were more pronounced in suppressors isolated from AZT exposure. Twenty of these suppressors were whole genome sequenced and mutations in dnaB, sspA, rpoA, and rpoC were found. These mutations indicated previously unknown interactions with holC. I propose that the chi subunit may have additional functions to its established role in DNA replication, particularly DNA transcription.