RESUMO
The filamentous fungus Aspergillus niger is widely exploited by the fermentation industry for the production of enzymes and organic acids, particularly citric acid. We sequenced the 33.9-megabase genome of A. niger CBS 513.88, the ancestor of currently used enzyme production strains. A high level of synteny was observed with other aspergilli sequenced. Strong function predictions were made for 6,506 of the 14,165 open reading frames identified. A detailed description of the components of the protein secretion pathway was made and striking differences in the hydrolytic enzyme spectra of aspergilli were observed. A reconstructed metabolic network comprising 1,069 unique reactions illustrates the versatile metabolism of A. niger. Noteworthy is the large number of major facilitator superfamily transporters and fungal zinc binuclear cluster transcription factors, and the presence of putative gene clusters for fumonisin and ochratoxin A synthesis.
Assuntos
Aspergillus niger/genética , Mapeamento Cromossômico , Cromossomos Fúngicos/genética , Genoma Fúngico/genética , Proteínas de Plantas/genética , Análise de Sequência de DNA/métodos , Sequência de Bases , Dados de Sequência MolecularRESUMO
The solution structure of the central repetitive domain of high molecular weight (HMW) wheat gluten proteins has been investigated for a range of concentrations and temperatures using mainly small-angle neutron scattering. A representative part of the repetitive domain (dB1) was studied as well as an "oligomer" basically consisting of four dB1 units, which has a length similar to the complete central domain. The scattering data over the entire angular range of both proteins are in quantitative agreement with a structural model based on a worm-like chain, a model frequently used in polymer theory. This model describes the "supersecondary structure" of dB1 and dB4 as a semiflexible cylinder with a length of about 235 and 900 A, respectively, and a cross-sectional diameter of about 15 A. The flexibility of both proteins is characterized by a persistence length of about 13 A. Their structures are thus quantitatively identical, which implies that the central HMW domain can be elongated while retaining its structural characteristics. It seems conceivable that the flexible cylinder results from a helical structure, which resembles the beta-spiral observed in earlier studies on gluten proteins and elastin. However, compared to the previously proposed structure of a (stiff) rod, our experiments clearly indicate flexibility of the cylinder.
