Regulação da expressão do gene plg1 que codifica pectina liase em Penicillium griseoroseum

• Autor(a) principal: Reis, Klédna Constância Portes
• Data de Publicação: 2006
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1552
• topic: Pectina liase; Penicillium griseoroseum; Pectin lyase; Penicillium griseoroseum; CNPQ::CIENCIAS BIOLOGICAS::GENETICA::GENETICA MOLECULAR E DE MICROORGANISMOS

Penicillium griseoroseum has been considered a promising species for industrial application because of its capacity to produce pectin lyase (PL) and polygalacturonase. When P. griseoroeum is grown in the presence of glucose, plg1 gene transcripts are detected at low levels, evidencing the effects of catabolic repression. However, in the absence of the natural inducer, pectin, and in the presence of sucrose supplemented with yeast extract and methylxanthines, plg1 transcripts are detected. The plg2 gene transcripts are detected at low levels in presence pectin, and it not being detected no product of amplification in conditions of catabolic repression The mutant strain M03 of P. griseoroseum is resistant to catabolic repression by high glucose concentrations in the culture medium, showing significant PL production. Substances that affect signal transduction pathways via cAMP, caffeine and NaF, act synergistically for PL production. When the mutant strain M03 is grown in media containing these substances, higher PL activities are observed in comparison to the wild type. Our results suggest that the differences in PL activity between the strains tested can be due to a cAMP-dependent signaling cascade and that the M03 produces a higher level of cAMP than the wild type, favoring the expression of the plg1 gene. The functional analysis of cis-elements located at the regulatory region of plg1 gene was investigated by the analyses of transformants containing different deletions in this region. This allowed the detection of a 319-bp fragment (b fragment), located at -506 and -187 upstream the +1 of transduction, important for the induction of plg1 in the presence of pectin. The plg1 induction by sucrose and yeast extract is not dependent of the same cis-elements involved in plg1 induction by pectin. The role of two CREA-binding cis-elements, located at -432 and -569, was also determined. Studies with point mutations in the b fragment may evidence essential sites for the induction of plg1. Such studies would allow advances towards the production of enzyme hiper-producing strains for industrial application and the expression of heterologous proteins in P. griseoroseum.