Penicillium notatum 1 a new source of dextranase

Summary Two hundred and fifteen fungal strains were screened for extracellular dextranase production with a diffusion plate method. The best enzymatic activity (12–19 DU ml^–1) was achieved byPenicillium notatum 1, a species for which the dextranase productivity has not yet been published. Some of the parameters affecting enzyme production have been standardized. The enzyme in crude state was relatively stable, its maximal activity was at 50°C and at pH 5.0. Conidia of the selected strain were mutagenized, and isolated mutants were tested for production of dextranase in submerged culture. The most active mutant,P. notatum 1-I-77, showed over two-times higher dextranase activity than the parentP. notatum 1     

Ivermectin 20 years on: maturation of a wonder drug

Ivermectin has been on the veterinary market for almost a quarter of a century and has been approved for human use for 18 years. Its use has revolutionized the treatment of nematode and arthropod parasites in animals and has provided hope for the control or even eradication of filariases in humans. Although much remains to be learned about how the drug works and how resistance to it will develop, it has earned the title of "wonder drug".     

Kinetically controlled drug resistance: how Penicillium brevicompactum survives mycophenolic acid

The filamentous fungus Penicillium brevicompactum produces the immunosuppressive drug mycophenolic acid (MPA), which is a potent inhibitor of eukaryotic IMP dehydrogenases (IMPDHs). IMPDH catalyzes the conversion of IMP to XMP via a covalent enzyme intermediate, E-XMP*; MPA inhibits by trapping E-XMP*. P. brevicompactum (Pb) contains two MPA-resistant IMPDHs, PbIMPDH-A and PbIMPDH-B, which are 17- and 10(3)-fold more resistant to MPA than typically observed. Surprisingly, the active sites of these resistant enzymes are essentially identical to those of MPA-sensitive enzymes, so the mechanistic basis of resistance is not apparent. Here, we show that, unlike MPA-sensitive IMPDHs, formation of E-XMP* is rate-limiting for both PbIMPDH-A and PbIMPDH-B. Therefore, MPA resistance derives from the failure to accumulate the drug-sensitive intermediate.     

Organophosphonate Utilization by the Wild-Type Strain of Penicillium notatum

We studied the biodegradation of compounds containing phosphorus-to-carbon bonds by using a wild-type strain of Penicillium notatum. The substrate specificity of this strain was studied, and we found that it is able to utilize structurally diverse organophosphonates as sole sources of phosphorus. This ability seems to be inducible, as indicated by the presence of a lag phase during growth. A popular herbicide, glyphosate, inhibited fungal growth, but it was also degraded by the fungus if it was applied in sublethal doses. This indicates that P. notatum may play an important role in biodegradation of organophosphonates. The strain which we used did not metabolize any of the phosphonates which we tested when they were used as sole carbon or nitrogen sources.     

Characterization of Pen n 13, a major allergen from the mold Penicillium notatum

Penicillium notatum is a well-known indoor aeroallergen and is frequently included in skin test panels for allergic diagnosis. On two-dimensional immunoblotting using patients' sera containing IgE and monoclonal antibody D7B8 specific for Pen c 1 of P. citrinum, two allergens with a molecular mass of 33 kDa but different isoelectric points were identified. A novel cDNA coding for Pen n 13 was cloned and sequenced. The nucleotide sequence codes for a protein 397 amino acids including a putative signal peptide of 25 amino acids and a propeptide of 90 amino acids. The allergen is an alkaline serine protease that shares more than 39% identical residues with other kinds of mold allergens. The coding cDNA of Pen n 13 was cloned into vector pQE-30 and expressed in E. coli M15 as a His-tag fusion protein and purified to homogeneity. The fusion protein reacted with monoclonal antibodies of Pen c 1 and with IgE from Penicillium-allergic patients. Furthermore, it also cross-reacted strongly with IgE specific for the natural Pen c 1, indicating that similar IgE binding epitopes may exist in the allergens of P. notatum and P. citrinum. Antigenicity index plots indicated that there are several similar epitope regions of high antigenic indices in Pen c 1 and Pen n 13, corroborating that mold allergens belonging to the alkaline serine protease family possess similar protein structure and strong antigenic cross-reactivity.     

Vaccinia complement control protein: Multi-functional protein and a potential wonder drug

Vaccinia virus complement control protein (VCP) was one of the first viral molecules demonstrated to have a role in blocking complement and hence in the evasion of host defense. Structurally it is very similar to the human C4b-BP and the other members of complement control protein. Functionally it is most similar to the CR1 protein. VCP blocks both major pathways of complement activation. The crystal structure of VCP was determined a little over a year ago and it is the only known structure of an intact and complete complement control protein. In addition to binding complement, VCP also binds to heparin. These two binding abilities can take place simultaneously and contribute to its many function and to its potential use in several inflammatory diseases, e.g. Alzheimer's disease (AD), CNS injury, xenotransplantation, etc. making it a truly fascinating molecule and potential drug.     

Microbial transformations of natural antitumor agents: oxidation of lapachol by Penicillium notatum.

The naphthoquinone lapachol (1) is readily metabolized by several fungi and streptomycetes. Preparative-scale fermentations with Penicillium notatum (UI 1602) provided a major polar metabolite (4), which was isolated and identified as an intermediate of the Hooker oxidation. The metabolite was synthesized by reacting lapachol with hydrogen peroxide under alkaline conditions.     

Oxidative ring fission of the naphthoquinones lapachol and dichloroallyl lawsone by Penicillium notatum

The naphthoquinones lapachol and dichloroallyl lawsone readily undergo oxidative ring fission when incubated with several fungi and streptomycetes. Penicillium notatum was employed to produce the ring fission product of dichloroallyl lawsone which was isolated and characterized by spectral analyses and chemical synthesis. The mechanism of oxidative ring fission of lapachol was studied by growing P. notatum cultures in an 18O2 atmosphere. Mass spectral analysis of the isolated and labeled metabolite indicates that ring fission occurs via a monooxygenase pathway most probably involving an epoxide intermediate.