Figure 1
Loss of cydAB and hmp impairs growth in the presence of NO.
(A) The NO-resistance mechanisms of E. coli: i) An NO-tolerant respiratory oxidase19 is induced (known as CydAB or cytochrome bd-I), which facilitates aerobic respiration under microaerobic conditions; ii) NO is converted to nitrate or nitrous oxide by the Flavohemoglobin Hmp under aerobic55 or anaerobic56 conditions, respectively; iii) NO is reduced by the periplasmic cytochrome c Nitrite Reductase NrfA57; iv) NO is converted to nitrous oxide via the Flavorubredoxin/Flavorubredoxin Reductase system NorVW15; v) The diiron protein YtfE repairs iron-sulphur clusters damaged by nitrosative stress18. (B–G) Cultures were grown under microaerobic conditions, and growth rates were measured following the addition of NOC-12 (0.2 mM and 0.5 mM). Error bars represent SD values. (H) Data from panels B-G are plotted as % growth rate compared to identical cultures grown in the absence of NOC-12. Error bars represent SEM. All data points are mean values calculated from five repeats. Asterisks indicate that rates measured in the presence of NOC-12 are significantly different from those measured in the absence of NOC-12 (Student’s t-test, P < 0.0001).
