An orphan-type cytochrome oxidase subunit supportsbiofilm growth and virulence.

Abstract

Hypoxia is a common challenge faced by bacteria during associations with hosts due in part to the formation of densely packed communities (biofilms).-type cytochromeoxidases, which catalyze the terminal step in respiration and have a high affinity for oxygen, have been linked to bacterial pathogenesis. The pseudomonads are unusual in that they often contain multiple full and partial (i.e. 'orphan') operons for-type oxidases and oxidase subunits. Here, we describe a unique role for the orphan catalytic subunit CcoN4 in colony biofilm development and respiration in the opportunistic pathogenPA14. We also show that CcoN4 contributes to the reduction of phenazines, antibiotics that support redox balancing for cells in biofilms, and to virulence in amodel of infection. These results highlight the relevance of the colony biofilm model to pathogenicity and underscore the potential of-type oxidases as therapeutic targets.