Transcription factor which plays an essential role in virulence by activating the transcription of iron uptake genes such as FRE7 in iron-poor environments such as the host bloodstream and internal organs. Promotes commensalism in a mouse model of gastrointestinal infection. Interacts with SSN3 and SFU1. Interaction with SFU1 promotes cytoplasmic localization whereas interaction with SSN3 and subsequent phosphorylation promotes nuclear localization. Nuclear localization is associated with virulence. Expression is regulated by changes of iron conditions with an increase in low iron. Transcription is negatively regulated by SFU1. Phosphorylated by SSN3 under iron-depleted conditions which leads to nuclear localization.