Gel mobility shift scanning of pectin-inducible promoter from Penicillium griseoroseum reveals the involvement of a CCAAT element in the expression of a polygalacturonase gene

Genome organization and assessment of high copy number and increased expression of pectinolytic genes from Penicillium griseoroseum: a potential heterologous system for protein production

The fungus Penicillium griseoroseum has the potential for application on an industrial scale as a host for the production of homologous and heterologous proteins, mainly because it does not produce some mycotoxins or secrete proteases under the growth conditions for pectinase production. However, for the fungus to be used effectively as an expression heterologous system, an understanding of the organization of its genome, as well as the mechanisms of gene expression and protein production, is required. In the present study, the size of the P. griseoroseum genome was estimated to be 29.8-31.5 Mb, distributed among four chromosomes. An analysis of plg1 and pgg2 pectinolytic genes expression and copy number in recombinant multi-copy strains of P. griseoroseum demonstrated that an increase in the number of gene copies could increase enzyme production, but the transcription could be affected by the gene integration position. Placing a copy of the plg1 gene under the control of the gpd promoter of Aspergillus nidulans yielded a 200-fold increase in transcription levels compared to the endogenous gene, and two copies of the pgg2 gene produced an 1100-fold increase compared with the endogenous gene. These results demonstrated that transcription, translation, and protein secretion in the fungus P. griseoroseum respond to an increased number of gene copies in the genome. The processing capacity and efficiency of protein secretion in P. griseoroseum are consistent with our premise that this fungus can be used for the industrial-scale production of several enzymes.

Improved pectinase production in Penicillium griseoroseum recombinant strains

AIMS

To obtain recombinant strains of Penicillium griseoroseum that produce high levels of pectin lyase (PL) and polygalacturonase (PG) simultaneously.

METHODS AND RESULTS

A strain with high production of PL was transformed with the plasmid pAN52pgg2, containing the gene encoding PG of P. griseoroseum, under control of the gpd promoter gene from Aspergillus nidulans. Southern blot analysis demonstrated that all strain had at least one copy of pAN52pgg2 integrated into the genome. The recombinant strain P. griseoroseum T20 produced levels of PL and PG that were 266- and 27-fold greater, respectively, than the wild-type strain. Furthermore, the extracellular protein profile of recombinant T20 showed two protein bands of c. 36 and 38 kDa, associated with PL and PG, respectively.

CONCLUSIONS

This recombinant strain T20 produces PL and PG using carbon sources of low costs, and an enzyme preparation that is free of cellulolytic and proteolytic activities.

SIGNIFICANCE AND IMPACT OF THE STUDY

PL and PG play an important role in the degradation of pectin. Owing to their use in the juice and wines industries, there is a growing interest in the inexpensive production of these enzymes. This work describes an efficient system of protein expression and secretion using the fungus P. griseoroseum.