ChIP Seq analysis of the Cu metalloregulatory transcription factor Cuf1 in Cryptococcus neoformans in response to Cu availability

The essential yet toxic nature of Cu ions in living cells requires exquisite control of Cu homeostasis. The fungal pathogen C. neoformans regulates Cu homeostasis for survival during a complex host colonization process. During pulmonary infection host innate immune cells use Cu in an attempt to toxify C. neoformans, which responds by activating expression of Cu detoxifying proteins. However, during brain colonization expression of the fungal Cu import machinery is activated and required for virulence. To achieve the genetic plasticity required for adaptation to a continuum of distinct Cu environments within the host, C. neoformans utilizes the Cu-responsive transcription factor, Cuf1. Cuf1 is unique as it senses and responds to both high and low Cu environments, activating different sets of genes dependent on environmental Cu status. Cells lacking Cuf1 are compromised for colonization of the lungs and brain, highlighting Cuf1 as an important virulence factor. A genome-wide assessment of the Cuf1 binding sites in the genome of C. neoformans driven by Cu status identified novel genes required for adaptation to high and low Cu environments. These genes and their regulation provide new insights with respect to adaptive responses to changes in host Cu availability and could reveal new targets for therapeutic intervention in cryptococcosis. ChIP-Seq was conducted in triplicate using a C. neoformans cuf1∆ strain complemented with a functional Cuf1-2xFLAG fusion protein. Cells were grown in SC until mid-log phase and treated with 1 mM CuSO4 (high Cu) or 1 mM bathocuproine disulfonate (BCS) (Cu deficiency) for three hours before cell harvesting. ChIP-Seq experiments were conducted in triplicate.