Gramicidin A is hydrolyzed by a D-stereospecific peptidase produced by Bacillus anthracis

Previously we described the discovery of a Bacillus spp. specific peptidase activity related to Dstereospecific peptidases (DSPs). The peptidase showed a strong preference for D-leucine and D-valine amino acids. These amino acids are present in the structure of the non-ribosomal peptide (NRP) antibiotics gramicidin A, B and C and polymyxin E. To...

In vitro phenotypic differentiation towards commensal and pathogenic oral biofilms

Commensal oral biofilms, defined by the absence of pathology-related phenotypes, are ubiquitously present. In contrast to pathological biofilms commensal biofilms are rarely studied. Here, the effect of the initial inoculum and subsequent growth conditions on in vitro oral biofilms was studied. Biofilms were inoculated with saliva and grown...

Bacillus globigii cell size is influenced by variants of the quorum sensing peptide extracellular death factor

Toxin-antitoxin modules are necessary for the mode of action of several antibiotics. One of the most studied toxin-antitoxin modules is the quorum sensing - dependent MazEF system in Escherichia coli. The quorum sensing factor in this system is called the extracellular death factor (EDF), a linear pentapeptide with the sequence NNWNN. In spite...

Evaluation of a D-amino-acid-containing fluorescence resonance energy transfer peptide library for profiling prokaryotic proteases

Bacterial proteases play an important role in a broad spectrum of processes, including colonization, proliferation, and virulence. In this respect, bacterial proteases are potential biomarkers for bacterial diagnosis and targets for novel therapeutic protease inhibitors. To investigate these potential functions, the authors designed and used a...

Rapid FRET-based diagnosis of bacterial pathogens

The invention comprises a substrate for detection of micro-organisms, wherein said substrate comprises a set of molecular markers linked, optionally with linker molecules or moeieties, to a di-, or tripeptide consisting of amino acids X1 and X2, or X1, X2 and X3, in which one of them, for example X1, is a D-amino acid and the others, for example...

A cathelicidin-2-derived peptide effectively impairs Staphylococcus epidermidis biofilms

Staphylococcus epidermidis is a major cause of nosocomial infections owing to its ability to form biofilms on the surface of medical devices. Biofilms are surface-adhered bacterial communities. In mature biofilms these communities are encased in an extracellular matrix composed of bacterial polysaccharides, proteins and DNA. The antibiotic...

Peptide-based fluorescence resonance energy transfer protease substrates for the detection and diagnosis of Bacillus species

We describe the development of a highly specific enzyme-based fluorescence resonance energy transfer (FRET) assay for easy and rapid detection both in vitro and in vivo of Bacillus spp., among which are the members of the B. cereus group. Synthetic substrates for B. anthracis proteases were designed and exposed to secreted enzymes of a broad...

A comprehensive study on the role of the Yersinia pestis virulence markers in an animal model of pneumonic plague

We determined the role of Yersinia pestis virulence markers in an animal model of pneumonic plague. Eleven strains of Y. pestis were characterized using PCR assays to detect the presence of known virulence genes both encoded by the three plasmids as well as chromosomal markers. The virulence of all Y. pestis strains was compared in a mouse model...

Avian cathelicidins: Paradigms for the development of anti-infectives

The broad-spectrum defense system based on host defense peptides (HDPs) is evolutionary very old and many invertebrates rely on this system for protection from bacterial infections. However, in vertebrates the system remained important in spite of the superposition of a very sophisticated adaptive immune system. The cathelicidins comprise a...

Improved proteolytic stability of chicken cathelicidin-2 derived peptides by d-amino acid substitutions and cyclization

A truncated version of host defense peptide chicken cathelicidin-2, C1-15, possesses potent, broad spectrum antibacterial activity. A variant of this peptide, F2,5,12W, which contains 3 phenylalanine to tryptophan substitutions, possesses improved antibacterial activity and lipopolysaccharide (LPS) neutralizing activity compared to C1-15. In...

Chicken cathelicidin-2-derived peptides with enhanced immunomodulatory and antibacterial activities against biological warfare agents

Host defence peptides (HDPs) are considered to be excellent candidates for the development of novel therapeutic agents. Recently, it was demonstrated that the peptide C1-15, an N-terminal segment of chicken HDP cathelicidin-2, exhibits potent antibacterial activity while lacking cytotoxicity towards eukaryotic cells. In the present study, we...

Rapid FRET based anthrax diagnosis

The invention comprises a substrate for detection of micro-organisms, wherein said substrate comprises a set of molecular markers linked to a di, tri- or tetrapeptide consisting of amino acids X1 and X2, X1, X2 and X3 or X1, X2, X3 and X4, respectively, in which one of them, for example X1 is a D-amino acid and the others, for example X2, X3 and...

DMBT1 functions as pattern-recognition molecule for poly-sulfated and poly-phosphorylated ligands

Deleted in malignant brain tumors 1 (DMBT1) is a secreted glycoprotein displaying a broad bacterial-binding spectrum. Recent functional and genetic studies linked DMBT1 to the suppression of LPS-induced TLR4-mediated NF-kappaB activation and to the pathogenesis of Crohn's disease. Here, we aimed at unraveling the molecular basis of its function...

Identification of chicken cathelicidin-2 core elements involved in antibacterial and immunomodulatory activities

Chicken host defense peptide cathelicidin-2 (CATH-2) is known to exert antimicrobial and immunomodulatory activities and consists of two α-helices connected by a hinge region. Here we report the biological properties of the separate α-helical segments and the importance of the proline residue in the hinge region. Substitution of proline-14 in...

Diagnosis of exposure to chemical warfare agents: An essential tool to counteract chemical terrorism

Methods to analyze chemical warfare agents (CW-agents) and their decomposition products in environmental samples were developed over the last decades. In contrast herewith, procedures for analysis in biological samples have only recently been developed. Retrospective detection of exposure to CW-agents is useful for various applications. It can...

Structure-function relationship of the human antimicrobial peptide LL-37 and LL-37 fragments in the modulation of TLR responses

Cathelicidins are effector molecules of the innate host defense system that establish an antimicrobial barrier at epithelial interfaces. The human cathelicidin LL-37, in addition to its antimicrobial activity, also exhibits immunomodulatory effects, such as inhibition of pro-inflammatory responses to bacterial LPS in human monocytic cells. In...

Detection of sulfur mustard adducts in human callus by phage antibodies

As part of a research program to develop novel methods for diagnosis of sulfur mustard exposure in the human skin the suitability of phage display was explored. Phage display is a relative new method that enables researchers to quickly evaluate a huge range of potentially useful antibodies, thereby bypassing the more costly and time-consuming...

Evaluation of the antibacterial spectrum of drosocin analogues

Drosocin is a 19-mer, cationic antimicrobial peptide from Drosophila melanogaster. The aim of the study was to examine the antibacterial spectrum of unglycosylated drosocin analogues. Furthermore, the amino acid sequence of DnaK, drosocin's intracellular target, from susceptible species was aligned and studied for sequence homology. From this a...