Protection from nitrosative stress: A central role for microbial flavohemoglobin

► Nitric oxide (NO) is a ubiquitous biological gas and central mediator of cytotoxic nitrosative stress. ► Bacteria and fungi counteract nitrosative stress by expressing flavohemoglobin (flavoHb), an efficient NO dioxygenase. ► FlavoHb deletion or inhibition confers hypersensitivity to nitrosative stress and impaired colonization in mammalian models of infection. ► Antifungal azoles may inhibit flavoHb, encouraging the development of more potent flavoHb inhibitors and antimicrobial drugs. ► In higher eukaryotes, heterologous expression of bacterial flavoHb may be used to study endogenous NO signaling pathways and therapeutically deplete NO.