RESUMO
MADS box transcription factors control diverse developmental processes in plants, metazoans, and fungi. To analyze the involvement of MADS box proteins in fruiting body development of filamentous ascomycetes, we isolated the mcm1 gene from the homothallic ascomycete Sordaria macrospora, which encodes a putative homologue of the Saccharomyces cerevisiae MADS box protein Mcm1p. Deletion of the S. macrospora mcm1 gene resulted in reduced biomass, increased hyphal branching, and reduced hyphal compartment length during vegetative growth. Furthermore, the S. macrospora Deltamcm1 strain was unable to produce fruiting bodies or ascospores during sexual development. A yeast two-hybrid analysis in conjugation with in vitro analyses demonstrated that the S. macrospora MCM1 protein can interact with the putative transcription factor SMTA-1, encoded by the S. macrospora mating-type locus. These results suggest that the S. macrospora MCM1 protein is involved in the transcriptional regulation of mating-type-specific genes as well as in fruiting body development.
Assuntos
Carpóforos/crescimento & desenvolvimento , Genes Fúngicos Tipo Acasalamento/fisiologia , Proteínas de Domínio MADS/metabolismo , Proteínas de Domínio MADS/fisiologia , Sordariales/crescimento & desenvolvimento , Sordariales/fisiologia , Sequência de Aminoácidos , Sequência de Bases , Núcleo Celular , Clonagem Molecular , Proteína 1 de Manutenção de Minicromossomo/genética , Proteína 1 de Manutenção de Minicromossomo/isolamento & purificação , Dados de Sequência Molecular , Mutação , Fenótipo , Deleção de Sequência , Homologia de Sequência de Aminoácidos , Distribuição Tecidual , Fatores de Transcrição/metabolismo , Fatores de Transcrição/fisiologiaRESUMO
The six MCM (minichromosome maintenance) proteins are essential DNA replication factors that each contain a putative ATP binding motif and together form a heterohexameric complex. We show that these motifs are required for viability in vivo and coordinated ATP hydrolysis in vitro. Mutational analysis discriminates between two functionally distinct MCM protein subgroups: Mcm4p, 6p, and 7p contribute canonical ATP binding motifs essential for catalysis, whereas the related motifs in Mcm2p, 3p, and 5p serve a regulatory function. Reconstitution experiments indicate that specific functional interactions between these two subgroups are required for robust ATP hydrolysis. Our observations show parallels between the MCM complex and the F1-ATPase, and we discuss how ATP hydrolysis by the MCM complex might be coupled to DNA strand separation.
