1,721,062 research outputs found
Molecular cloning of Bac7, a proline- and arginine-rich antimicrobial peptide from bovine neutrophils.
No full textStructural organization of the bovine cathelicidin gene family and identification of a novel member.
No full textProteolytic cleavage by neutrophil elastase converts inactive storage proforms to antibacterial bactenecins.
No full textBacS and Bac7, antibiotics of the bactenecin (proline/arginine-rich peptide) family, are stored as
proforms in the large granules of bovine neutrophils [Zanetti, M., Litteri, L., Gennaro, R.,
Horstmann, H. and Romeo, D. (1990) J. Cell Bid. I l l , 1363-13711. These proforms have been
purified to homogeneity from granule extracts by immunoaffinity and reverse-phase chromatography.
While mature bactenecins efficiently kill Escherichia coli, Klebsiella pneumoniae and Salmonella
typhimurium with minimal inhibitory concentrations of 6- 12 pg/ml, proBac5 and proBac7 do not
affect the growth of the same microorganisms, even at 500 pg/ml. Previous investigations have
suggested that the conversion of probactenecins into mature antimicrobial peptides is catalyzed by a
neutral serine protease stored in the azurophil granules. Purified proBac5 and proBac7 were thus
treated with elastase, cathepsin G or proteinase 3, which constitute the pool of neutral serine
proteases of the azurophils, and the reaction products were identified by Western blot analysis, mass
spectrometry, and N-terminal sequence analysis. Of the three proteases, only elastase is able to
catalyze the stepwise cleavage of probactenecins into the corresponding mature fieptides, which have
the same mass, N-terminal sequence and antibiotic activity of authentic BacS and Bac7. These results
point to the importance of cooperation between azurophils and large granules in mounting a defense
reaction
PMAP-37, a novel antibacterial peptide from pig myeloid cells: c-DNA cloning, chemical synthesis and activity
No full textA molecular biological approach, based on preproregion homology in the precursors of several diverse antibacterial peptides, was used to clone a pig bone marrow cDNA encoding a novel 167-residue polypeptide. The preproregion of this polypeptide is highly similar to corresponding regions in congeners from pig, cattle and rabbit. It is followed by a unique, cationic, 37-residue sequence, which was predicted to have a high propensity for an α-helical conformation. A peptide, termed PMAP-37, corresponding to this sequence, was chemically synthesized and shown to undergo a transition from a random coil to an ordered, mainly helical, conformation on addition of trifluoroethanol. This behaviour is typical of an amphipathic α helix, a structure common to several membrane-active, antimicrobial peptides. In vitro experiments showed that PMAP-37 strongly inhibits the growth of several strains of Gram-negative and Gram-positive bacteria, with minimal inhibitory concentrations ranging over 1–4 μM, and permeabilizes the inner membrane of Escherichia coll. Interestingly, the 15–32 stretch of PMAP-37 show a remarkable similarity to N-terminal stretches in cecropins B and A from Drosophila melanogaster and Cecropia hyalophora, respectively. This affords an uncommon example of sequence convergence
Rapid and reliable detection of antimicrobial peptide penetration into Gram-negative bacteria based on fluorescence quenching.
No full textIn this paper, we describe a rapid flow cytometry method to identify antimicrobial peptides that are
internalized into bacterial cells and differentiate them from those that are membrane active. The method was
applied to fluorescently labeled Bac71-35 and polymyxin B, whose mechanisms of action are, respectively, based
on cell penetration and on membrane binding and permeabilization. Identification of peptides with the former
mechanism is of considerable interest for the intracellular delivery of membrane-impermeant drugs
Chemical synthesis and biological activity of a novel antibacterial peptide deduced from a pig myeloid cDNA.
No full textSeveral myeloid precursors of antibacterial peptides have recently been shown to share homologous pre- and pro-regions. Taking advantage of this homology, a novel cDNA was cloned from pig bone marrow RNA. This encodes a 166-residue polypeptide with highly conserved pre- (29 residues) and pro- (10l residues) sequences, followed by a unique, 36-residue C-terminal sequence. Structure analyses of this C-terminal region have identified a highly cationic sequence predicted to adopt an amphipathic α-helical conformation. A peptide corresponding to this sequence was chemically synthesized and shown to arrest the growth of both Gram-positive and Gram-negative bacteria. At least for Escherichia coli, the activity of this peptide appears to be mediated by its ability to permeabilize the bacterial membranes
Search for Shorter Portions of the Proline-Rich Antimicrobial Peptide Fragment Bac5(1–25) That Retain Antimicrobial Activity by Blocking Protein Synthesis
No full textThe spread of antibiotic-resistant pathogens has boosted the
search for new antimicrobial drugs. Proline-rich antimicrobial
peptides are promising lead compounds for the development
of next-generation antibiotics, given their very low cytotoxicity
and their good antimicrobial activity targeting the bacterial ribosome.
Bac5(1–25) is an N-terminal fragment of the bovine
proline-rich antimicrobial peptide Bac5, whose mode of action
has been recently described. In this work we tested a number
of Bac5(1–25) fragments, and we characterized their antimicrobial
activity against Escherichia coli, Acinetobacter baumannii,
Klebsiella pneumoniae, Staphylococcus aureus, Salmonella enterica,
and Pseudomonas aeruginosa. We evaluated their cytotoxicity
toward human cells and their efficacy in inhibiting bacterial
protein synthesis. This allowed us to identify some shorter
fragments of Bac5(1–25) with a good balance between antibacterial
efficacy, protein synthesis inhibition, and ease/cost-effectiveness
of synthesis, suitable as lead compounds to develop
new antibacterials
Genome-wide Transcriptional profiling of the Escherichia coli response to a Proline-rich antimicrobial peptide
No full textMost antimicrobial peptides (AMPs) impair the viability of target bacteria by permeabilizing bacterial
membranes. However, the proline-rich AMPs have been shown to kill susceptible organisms without causing
significant membrane perturbation and may act by inhibiting the activity of bacterial targets. To gain initial
insight into the events that follow interaction of a proline-rich peptide with bacterial cells, we used DNA
macroarray technology to monitor transcriptional alterations of Escherichia coli in response to challenge with
a subinhibitory concentration of the proline-rich Bac7(1-35). Substantial changes in the expression levels of 70
bacterial genes from various functional categories were detected. Among these, 26 genes showed decreased
expression, while 44 genes, including genes that are potentially involved in bacterial resistance to antimicrobials,
showed increased expression. The generation of a transcriptional response under the experimental
conditions used is consistent with the ability of Bac7(1-35) to interact with bacterial components and affect
biological processes in this organism
- …
