Research experience
-
Jan 2010
Research: Rheinische Friedrich-Wilhelms-Universität Bonn
Rheinische Friedrich-Wilhelms-Universität Bonn · Institute of Medical Microbiology, Immunology and ParasitologyGermany · Bonn -
Jan 2009
Research: Statens Serum Institut
Statens Serum InstitutDenmark · Copenhagen -
Jan 1998–
presentResearch: Novozymes A/S
Novozymes A/SDenmark · Copenhagen
Publications (21) View all
-
Article: Eurocin, a new fungal defensin: structure, lipid binding and its mode of action.
[show abstract] [hide abstract]
ABSTRACT: Antimicrobial peptides are a new class of antibiotics that are promising for pharmaceutical applications, since they have retained efficacy throughout evolution. One class of antimicrobial peptides are the defensins, that have been found in different species. Here we describe a new fungal defensin, eurocin. Eurocin acts against a range of gram-positive human pathogens, but not against gram-negative bacteria. Eurocin consists of 42 amino acids, forming a cysteine-stabilized α/β fold. Thermal denaturation data point shows the disulphide bridges being responsible for the stability of the fold. Eurocin does not form pores in cell membranes at physiologically relevant concentrations, it does, however, lead to limited leakage of a fluorophore from small unilamellar vesicles. Eurocin interacts with detergent micelles, and it inhibits the synthesis of cell walls by binding equimolarly to the cell wall precursor lipid II.Journal of Biological Chemistry 10/2012; · 4.77 Impact Factor -
Article: Identification of defensin-encoding genes of Picea glauca: characterization of PgD5, a conserved spruce defensin with strong antifungal activity.
[show abstract] [hide abstract]
ABSTRACT: BACKGROUND: Plant defensins represent a major innate immune protein superfamily that displays strong inhibitory effects on filamentous fungi. The total number of plant defensins in a conifer species is unknown since there are no sequenced conifer genomes published, however the genomes of several angiosperm species provide an insight on the diversity of plant defensins. Here we report the identification of five new defensin-encoding genes from the Picea glauca genome and the characterization of two of their gene products, named PgD5 and endopiceasin. RESULTS: Screening of a P. glauca EST database with sequences of known plant defensins identified four genes with homology to the known P. glauca defensin PgD1, which were designated PgD2-5. Whereas in the mature PgD2-4 only 7--9 amino acids differed from PgD1, PgD5 had only 64% sequence identity. PgD5 was amplified from P. glauca genomic DNA by PCR. It codes for a precursor of 77-amino acid that is fully conserved within the Picea genus and has similarity to plant defensins. Recombinant PgD5, produced in Escherichia coli, had a molecular mass of 5.721 kDa, as determined by mass spectrometry. The PgD5 peptide exhibited strong antifungal activity against several phytopathogens without any effect on the morphology of the treated fungal hyphae, but strongly inhibited hyphal elongation. A SYTOX uptake assay suggested that the inhibitory activity of PgD5 could be associated with altering the permeability of the fungal membranes. Another completely unrelated defensin gene was identified in the EST library and named endopiceasin. Its gene codes for a 6-cysteine peptide that shares high similarity with the fungal defensin plectasin. CONCLUSIONS: Screening of a P. glauca EST database resulted in the identification of five new defensin-encoding genes. PgD5 codes for a plant defensin that displays non-morphogenic antifungal activity against the phytopathogens tested, probably by altering membrane permeability. PgD5 has potential for application in the plant biotechnology sector. Endopiceasin appears to derive from an endo- or epiphytic fungal strain rather than from the plant itself.BMC Plant Biology 10/2012; 12(1):180. · 3.45 Impact Factor -
Article: Transcriptional Profile of Escherichia coli in Response to Novispirin G10
[show abstract] [hide abstract]
ABSTRACT: Using a novel methodology, we have investigated the transcriptional response of Escherichia coli to novispirin G10, an α-helical cationic antimicrobial peptide. We show that novispirin G10 induces an exceptionally coherent transcriptional response in E.coli, resulting in upregulation of genes involved in response to osmotic stress, acid shock, phage shock, and antimicrobial peptides, and down-regulation of the heat shock response genes, e.g., dnaJK, GroES, and GroEL. This transcriptional pattern indicates that novispirin G10 acts by compromising the bacterial membrane and possibly also by targeting the heat shock response. The impact of novispirin G10 on E.coli cells was monitored directly using the fluorescent LIVE/DEAD assay verifying that the peptide, indeed, targets bacterial membranes. Furthermore, in agreement with the observed heat shock transcriptional response, we show that overexpression of the heat shock transcription factor in E.coli, σ32, leads to a significant decrease in sensitivity towards novispirin G10.International Journal of Peptide Research and Therapeutics 04/2012; 15(1):17-24. · 0.99 Impact Factor -
Article: Efficacy of NZ2114, a novel plectasin-derived cationic antimicrobial peptide antibiotic, in experimental endocarditis due to methicillin-resistant Staphylococcus aureus.
[show abstract] [hide abstract]
ABSTRACT: Cationic antimicrobial peptides (CAPs) play important roles in host immune defenses. Plectasin is a defensin-like CAP isolated from the saprophytic fungus Pseudoplectania nigrella. NZ2114 is a novel variant of plectasin with potent activity against Gram-positive bacteria. In this study, we investigated (i) the in vivo pharmacokinetic and pharmacodynamic (PK/PD) characteristics of NZ2114 and (ii) the in vivo efficacy of NZ2114 in comparison with those of two conventional antibiotics, vancomycin or daptomycin, in an experimental rabbit infective endocarditis (IE) model due to a methicillin-resistant Staphylococcus aureus (MRSA) strain (ATCC 33591). All NZ2114 regimens (5, 10, and 20 mg/kg of body weight, intravenously [i.v.], twice daily for 3 days) significantly decreased MRSA densities in cardiac vegetations, kidneys, and spleen versus those in untreated controls, except in one scenario (5 mg/kg, splenic MRSA counts). The efficacy of NZ2114 was clearly dose dependent in all target tissues. At 20 mg/kg, NZ2114 showed a significantly greater efficacy than vancomycin (P < 0.001) and an efficacy similar to that of daptomycin. Of importance, only NZ2114 (in 10- and 20-mg/kg regimens) prevented posttherapy relapse in cardiac vegetations, kidneys, and spleen, while bacterial counts in these target tissues continued to increase in vancomycin- and daptomycin-treated animals. These in vivo efficacies were equivalent and significantly correlated with three PK indices investigated: fC(max)/MIC (the maximum concentration of the free, unbound fraction of a drug in serum divided by the MIC), fAUC/MIC (where AUC is the area under the concentration-time curve), and f%T(>MIC) (%T(>MIC) is the cumulative percentage of a 24-h period that the drug concentration exceeds the MIC under steady-state pharmacokinetic conditions), as analyzed by a sigmoid maximum-effect (E(max)) model (R(2) > 0.69). The superior efficacy of NZ2114 in this MRSA IE model suggests the potential for further development of this compound for treating serious MRSA infections.Antimicrobial Agents and Chemotherapy 08/2011; 55(11):5325-30. · 4.84 Impact Factor -
Article: Intracellular activity of the peptide antibiotic NZ2114: studies with Staphylococcus aureus and human THP-1 monocytes, and comparison with daptomycin and vancomycin.
[show abstract] [hide abstract]
ABSTRACT: Staphylococcus aureus survives inside eukaryotic cells. Our objective was to assess the activity of NZ2114, a novel peptidic antibiotic, against intracellular S. aureus in comparison with established antistaphylococcal agents acting on the bacterial envelope with a distinct mechanism. The extracellular (broth) and intracellular (THP-1 monocytes) activities of NZ2114 were compared with those of vancomycin and daptomycin against methicillin-susceptible S. aureus (MSSA), methicillin-resistant S. aureus (MRSA) and vancomycin-resistant S. aureus (VRSA). All three compounds showed an extracellular bactericidal effect (>3 log(10) kill) against MSSA and MRSA. Daptomycin and NZ2114 also exhibited bactericidal activity against VRSA. The extracellular killing was concentration dependent for all three compounds within the range of drug concentrations tested. The intracellular experiments demonstrated a maximal intracellular effect of NZ2114 after 24 h as a 5 log(10) cfu reduction against MSSA (ATCC 25923), while the activity was a 0.9 log(10) cfu reduction against MRSA and a 0.2 log(10) cfu reduction against VRSA. For comparison, the intracellular activity of daptomycin was a 1.0 log(10) cfu reduction against MSSA, a 0.8 log(10) cfu reduction against MRSA and a 0.3 log(10) cfu reduction against VRSA. Vancomycin showed activity against both MSSA and MRSA (0.6 log(10) cfu reduction), whereas VRSA was resistant to vancomycin. NZ2114 displayed similar extracellular and intracellular activities as daptomycin, and was more effective than vancomycin against the intracellular forms of susceptible bacteria. However, the study also showed that the intracellular activities of NZ2114 and daptomycin are weaker than their extracellular activities.Journal of Antimicrobial Chemotherapy 08/2010; 65(8):1720-4. · 5.07 Impact Factor
