Não consta resumo na publicação. / The gene encoding actin in the cellulolytic filamentus fungus Trichoderma reesei has been isolated and sequenced. The nucleotide sequence reveals that the gene is composed of 6 exons separated by 5 introns within the coding region. The positions of the introns were predicted by comparison of sequence homology to the genes coding for actin with known amino acid sequence and by identification of splice-site signal sequences. The actin protein of Trichoderma reesei shows extensive homology to the actins of other fungi E. nidulans, 95% , T. lanuginosus, 92% and S. pombae. The T. reesei actin promoter has a CT-rich region, CAAT and GC. There is no obvious TATA sequence in the T. reesei actin promoter. The absence of TATA-like sequence were also observed in anothers genes of T. reesei. An important aspect in molecular biology of filamentous fungi is the analysis, under a specific metabolic events, of the mechanism(s) regulating the expression of constitutive and induced genes. The filamentous fungus Trichoderma reesei is considered to be one of the most efficient producer of cellulase, and it serves as a model system for enzymatic cellulose hydrolysis. Expression of the cellulase genes are stringently regulated by the carbon source. Growth on cellulose results in induction of the cellulase transcripts, whereas glucose strongly represses their expression. The availability of a constitutive expressed genes of T. reesei provides not only important information regarding the molecular biology of the fungi, but also is essential for a better understanding of the mechanism(s) controlling the expression of the cellulase transcripts. Under inductive process of the of the major cellulase transcript (cbh1) and its repression by glucose, actin mRNA is constitutively expressed. The present results should be useful for further structural and functional analysis of the elements involved in inductive and constitutive expression of cellulase and actin transcripts.

O gene TrSNF1, homólogo aos membros da subfamília das proteínas serina-treonina quinases ativadas por AMP (AMPK) e relacionadas a SNF1, foi isolado do fungo filamentoso trichoderma reesei. A seqüência de aminoácidos putativa possui um domínio de quinase com 42% de identidade e 59% de similaridade com outras proteínas quinases da mesma subfamília. Em S. cerevisiae a SNFl é essencial para a expressão de genes reprimidos por glicose, em resposta a privação de glicose do meio de cultura. A expressão de TrSNFl em levedura mutante para SNF1, restaura a função de SNF1. A expressão de um antisense de TrSNFl em T. reesei causa um atraso na expressão do gene regulado por glicose, CBHI. Além disso, em experimento utilizando matrizes de DNA foi possível observar uma alteração da tendência global da expressão gênica entre a cepa selvagem e a cepa antisense. A observação da homologia estrutural com proteínas quinase da mesma subfamília, a similaridade funcional com SNFl de S. cerevisiae, e a alteração no padrão da expressão gênica in vivo, sugerem que TrSNFl pode estar envolvido na regulação do metabolismo de carboidratos em T. reesei. / A gene homologue to the members of the AMP-activated/SNFl protein kinase subfamily, TrSNF1, was isolated from the filamentous fungus Trichoderma reesei. The predicted protein of 692 amino acids has a kinase domain, that share 42 % identity and 59 % similarity to that of serine/threonine protein kinase of this family. In Saccharomyces cerevisiae, the SNFl protein kinase is required for expression of glucose repressed genes in response to withdrawal of glucose from the medium. Expression of the Trichoderma reesei SNF1-related sequence in yeast SNFl mutant restores SNFl function. The TrSNFl antisense expression in T. reesei causes a control alteration in the glucose-regulated gene CBHI. The observed structural identity with the AMP-activated/SNFl protein kinase subfamily, and the functional similarity to the yeast SNFl suggest that the TrSNFl may be involved in the regulation of sugar metabolism in Trichoderma reesei.

Não consta resumo na publicação. / The gene encoding actin in the cellulolytic filamentus fungus Trichoderma reesei has been isolated and sequenced. The nucleotide sequence reveals that the gene is composed of 6 exons separated by 5 introns within the coding region. The positions of the introns were predicted by comparison of sequence homology to the genes coding for actin with known amino acid sequence and by identification of splice-site signal sequences. The actin protein of Trichoderma reesei shows extensive homology to the actins of other fungi E. nidulans, 95% , T. lanuginosus, 92% and S. pombae. The T. reesei actin promoter has a CT-rich region, CAAT and GC. There is no obvious TATA sequence in the T. reesei actin promoter. The absence of TATA-like sequence were also observed in anothers genes of T. reesei. An important aspect in molecular biology of filamentous fungi is the analysis, under a specific metabolic events, of the mechanism(s) regulating the expression of constitutive and induced genes. The filamentous fungus Trichoderma reesei is considered to be one of the most efficient producer of cellulase, and it serves as a model system for enzymatic cellulose hydrolysis. Expression of the cellulase genes are stringently regulated by the carbon source. Growth on cellulose results in induction of the cellulase transcripts, whereas glucose strongly represses their expression. The availability of a constitutive expressed genes of T. reesei provides not only important information regarding the molecular biology of the fungi, but also is essential for a better understanding of the mechanism(s) controlling the expression of the cellulase transcripts. Under inductive process of the of the major cellulase transcript (cbh1) and its repression by glucose, actin mRNA is constitutively expressed. The present results should be useful for further structural and functional analysis of the elements involved in inductive and constitutive expression of cellulase and actin transcripts.