Iron-Sulfur Cluster Repair Contributes to Yersinia pseudotuberculosis Survival within Deep Tissues

Abstract

To successfully colonize host tissues, bacteria must respond to and detoxify many different host-derived antimicrobial compounds, such as nitric oxide (NO). NO has direct antimicrobial activity through attack on iron-sulfur (Fe-S) cluster-containing proteins. NO detoxification plays an important role in promoting bacterial survival, but it remains unclear if repair of Fe-S clusters is also important for bacterial survival within host tissues. Here we show that the Fe-S cluster repair protein YtfE contributes to the survival of <i>Yersinia pseudotuberculosis</i> within the spleen following nitrosative stress. <i>Y. pseudotuberculosis</i> forms clustered centers of replicating bacteria within deep tissues, where peripheral bacteria express the NO-detoxifying gene <i>hmp. ytfE</i> expression also occurred specifically within peripheral cells at the edges of microcolonies. In the absence of <i>ytfE</i>, the area of microcolonies was significantly smaller than that of the wild type (WT), consistent with <i>ytfE</i> contributing to the survival of peripheral cells. The loss of <i>ytfE</i> did not alter the ability of cells to detoxify NO, which occurred within peripheral cells in both WT and Δ<i>ytfE</i> microcolonies. In the absence of NO-detoxifying activity by <i>hmp</i>, NO diffused across Δ<i>ytfE</i> microcolonies, and there was a significant decrease in the area of microcolonies lacking <i>ytfE</i>, indicating that <i>ytfE</i> also contributes to bacterial survival in the absence of NO detoxification. These results indicate a role for Fe-S cluster repair in the survival of <i>Y. pseudotuberculosis</i> within the spleen and suggest that extracellular bacteria may rely on this pathway for survival within host tissues.