Abstract
BackgroundFungal mating types in self-incompatible Pezizomycotina are specified by one of two alternate sequences occupying the same locus on corresponding chromosomes. One sequence is characterized by a gene encoding an HMG protein, while the hallmark of the other is a gene encoding a protein with an α1 domain showing similarity to the Matα1p protein of Saccharomyces cerevisiae. DNA-binding HMG proteins are ubiquitous and well characterized. In contrast, α1 domain proteins have limited distribution and their evolutionary origin is obscure, precluding a complete understanding of mating-type evolution in Ascomycota. Although much work has focused on the role of the S. cerevisiae Matα1p protein as a transcription factor, it has not yet been placed in any of the large families of sequence-specific DNA-binding proteins.Methodology/Principal FindingsWe present sequence comparisons, phylogenetic analyses, and in silico predictions of secondary and tertiary structures, which support our hypothesis that the α1 domain is related to the HMG domain. We have also characterized a new conserved motif in α1 proteins of Pezizomycotina. This motif is immediately adjacent to and downstream of the α1 domain and consists of a core sequence Y-[LMIF]-x(3)-G-[WL] embedded in a larger conserved motif.Conclusions/SignificanceOur data suggest that extant α1-box genes originated from an ancestral HMG gene, which confirms the current model of mating-type evolution within the fungal kingdom. We propose to incorporate α1 proteins in a new subclass of HMG proteins termed MATα_HMG.
Highlights
Mating types in fungi display highly variable structure and content (Figure 1); in Ascomycota, they consist of dissimilar sequences occupying the same locus on the chromosome
The a1 protein Mata1p was initially characterized in Saccharomyces cerevisiae [5] and a1 domain proteins were subsequently found to be ubiquitous in Ascomycotina [4,6]
A total of 5,773 sequence sets corresponding to a1 domains from Ascomycota and HMG domains from fungi, plants and animals were aligned with the core region using Muscle [18] and conserved sequences identified
Summary
Mating types in fungi display highly variable structure and content (Figure 1); in Ascomycota, they consist of dissimilar sequences occupying the same locus on the chromosome. The constant presence of an a1-box gene in one idiomorph constitutes the basis for mating-type nomenclature in self-incompatible (heterothallic) Pezizomycotina [7]. This gene is called MAT1-1-1 and defines the MAT1-1 idiomorph, while the other idiomorph called MAT1-2, is characterized by the presence of a MAT1-2-1 gene which encodes a transcription factor with a MATA_HMG domain. Much work has focused on the role of the S. cerevisiae Mata1p protein as a transcription factor, it has not yet been placed in any of the large families of sequence-specific DNA-binding proteins
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
