title: Cognate Site Identifier analysis reveals novel binding properties of the Sex Inducer homeodomain proteins of Cryptococcus neoformans.
abstract: Homeodomain proteins function in fungi to specify cell types and control sexual development. In the meningoencephalitis-causing fungal pathogen Cryptococcus neoformans, sexual development leads to the production of spores (suspected infectious particles). Sexual development is controlled by the homeodomain transcription factors Sxi1alpha and Sxi2a, but the mechanism by which they act is unknown. To understand how the Sxi proteins regulate development, we characterized their binding properties in vitro, showing that Sxi2a does not require a partner to bind DNA with high affinity. We then utilized a novel approach, Cognate Site Identifier (CSI) arrays, to define a comprehensive DNA-binding profile for Sxi2a, revealing a consensus sequence distinct from those of other fungal homeodomain proteins. Finally, we show that the homeodomains of both Sxi proteins are required for sexual development, a departure from related fungi. Our findings support a model in which Sxi1alpha and Sxi2a control sexual development in a homeodomain-dependent manner by binding to DNA sequences that differ from those defined in previously established fungal paradigms.
authors.affiliation: Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin, Madison, Madison, WI 53706, USA.
authors.forename: Brynne C
authors.initials: BC
authors.lastname: Stanton
authors.forename: Steven S
authors.initials: SS
authors.lastname: Giles
authors.forename: Emilia K
authors.initials: EK
authors.lastname: Kruzel
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Warren
authors.forename: Aseem Z
authors.initials: AZ
authors.lastname: Ansari
authors.forename: Christina M
authors.initials: CM
authors.lastname: Hull
mesh_terms: D016384:Consensus Sequence; D003455:Cryptococcus neoformans / Q000235:genetics* / Q000378:metabolism; D004271:DNA, Fungal / Q000235:genetics; D024202:Electrophoretic Mobility Shift Assay; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D005816:Genetic Complementation Test; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D020411:Oligonucleotide Array Sequence Analysis; D011485:Protein Binding; D013379:Substrate Specificity; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D004271:DNA, Fungal; D005656:Fungal Proteins; D018398:Homeodomain Proteins; D014157:Transcription Factors