Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Análise Mutacional de DNA , Leucemia Mielomonocítica Crônica/genética , Fosfoproteínas/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Células da Medula Óssea/citologia , Estudos de Coortes , Proteínas de Ligação a DNA/genética , Regulação para Baixo , Éxons , Feminino , Heterozigoto , Humanos , Masculino , Camundongos , Pessoa de Meia-Idade , Mutação , Mutação Puntual , Estrutura Terciária de Proteína , Proteínas de Ligação a RNA/genética , Transdução de SinaisRESUMO
In the heterothallic filamentous fungus Podospora anserina, four mating-type genes encoding transcriptional factors have been characterized: FPR1 in the mat+ sequence and FMR1, SMR1, and SMR2 in the alternative mat- sequence. Fertilization is controlled by FPR1 and FMR1. After fertilization, male and female nuclei, which have divided in the same cell, form mat+/mat- pairs during migration into the ascogenous hyphae. Previous data indicate that the formation of mat+/mat- pairs is controlled by FPR1, FMR1, and SMR2. SMR1 was postulated to be necessary for initial development of ascogenous hyphae. In this study, we investigated the transcriptional control of the mat genes by seeking mat transcripts during the vegetative and sexual phase and fusing their promoter to a reporter gene. The data indicate that FMR1 and FPR1 are expressed in both mycelia and perithecia, whereas SMR1 and SMR2 are transcribed in perithecia. Increased or induced vegetative expression of the four mat genes has no effect when the recombined gene is solely in the wild-type strain. However, the combination of resident FPR1 with deregulated SMR2 and overexpressed FMR1 in the same nucleus is lethal. This lethality is suppressed by the expression of SMR1, confirming that SMR1 operates downstream of the other mat genes.
Assuntos
Ascomicetos/genética , Núcleo Celular/metabolismo , Genes Letais , Peptídeos/genética , Regiões 5' não Traduzidas , Sequência de Bases , Primers do DNA , Fator de Acasalamento , Fenótipo , RNA Mensageiro/genéticaRESUMO
The two idiomorphic alleles called mat+ and mat-, which control the mating types in Podospora anserina, have been cloned. Mat+ and mat- encompass 3.8 kb and 4.7 kb respectively, of unrelated DNA sequences flanked by common sequences. Subcloning allowed the identification and localization in each locus of the gene that controls fertilization, probably by determining the mating type. The mat+ gene, called FPR1, encodes a protein with a potential DNA-binding HMG domain. The presence of this motif suggests that the FPR1 polypeptide may act as a transcriptional factor. The mat- gene called FMR1 encodes a protein containing a motif that is also found in proteins controlling mating functions in Saccharomyces cerevisiae and Neurospora crassa. The role of this motif has not yet been established. Unlike the mat+ locus, where the FPR1 gene seems to represent the major information, the mat- locus contains information necessary for the post-fertilization steps of the sexual cycle besides the FMR1 gene.
Assuntos
Ascomicetos/genética , Proteínas de Ligação a DNA/genética , Proteínas Fúngicas/genética , Genes Fúngicos , Genes Fúngicos Tipo Acasalamento , Sequência de Aminoácidos , Ascomicetos/fisiologia , Sequência de Bases , Cromossomos Fúngicos , Clonagem Molecular , DNA Fúngico/genética , Proteínas de Grupo de Alta Mobilidade/genética , Dados de Sequência Molecular , Neurospora crassa/genética , Neurospora crassa/fisiologia , Plasmídeos , Mapeamento por Restrição , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/fisiologia , Alinhamento de Sequência , Transformação GenéticaRESUMO
DNAs that encode the mating-type functions (mat+ and mat-) of the filamentous fungus Podospora anserina were cloned with the use of the mating-type A probe from Neurospora crassa. Cloning the full mat information was ascertained through gene replacement experiments. Molecular and functional analyses of haploid transformants carrying both mating types lead to several striking conclusions. Mat+ mat- strains are dual maters. However, the resident mat information is dominant to the mat information added by transformation with respect to fruiting body development and ascus production. Moreover, when dual mating mat+ mat- strains are crossed to mat+ or mat- testers, there is strong selection, after fertilization, that leads to the loss from the mat+ mat- nucleus of the mat information that matches that of the tester. Finally, the mat locus contains at least two domains, one sufficient for fertilization, the other necessary for sporulation.