Nitric Oxide Sensitivity in Single Knockout Escherichia coli Mutants

Abstract

Nitric oxide is utilized in the protective functions of macrophages. The molecule represents significant danger for both mammalian and bacterial cells. The affects in E. coli cells range from inhibition of protein synthesis to peroxidation of membrane lipids, all potentially lethal without protective mechanisms. Multiple pathways were developed in order to defend against this stressor. The aerobic pathway results in the production and activation of Hmp, a flavohemoglobin that works to dioxygenate the molecule. While much is known about the aerobic pathway for nitric oxide detoxification, other genes have been shown to increase transcription under nitric oxide stress. The goal of this project was to investigate some of these genes through single gene knockout mutations in the E. coli strain MG1655. We found that none of the eight genes tested showed a significant change in nitric oxide clearance when exposed under aerobic conditions. Further work is necessary to continue investigating the genes that demonstrate increased transcription under nitric oxide stress.