ORCID Profile
0000-0001-8311-1096
Current Organisation
X2 Science Solutions Lda
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Publisher: Elsevier BV
Date: 03-2013
DOI: 10.1016/J.BBAMEM.2012.12.002
Abstract: BP100 is a short cationic antimicrobial peptide with a mechanism of action dependent on peptide-lipid interactions and microbial surface charge neutralization. Although active against Gram-negative bacteria, BP100 is inactive against Gram-positive bacteria. In this study we report two newly designed BP100 analogues, RW-BP100 and R-BP100 that have the Tyr residue replaced with a Trp and/or the Lys residues replaced with an Arg. The new analogues in addition to being active against Gram-negative bacteria, possess activity against all tested Gram-positive bacteria. Mechanistic studies using atomic force microscopy, surface plasmon resonance and fluorescence methodologies reveal that the antibacterial efficiency follows the affinity for bacterial membrane. The studies suggest that the activity of BP100 and its analogues against Gram-negative bacteria is mainly driven by electrostatic interactions with the lipopolysaccharide layer and is followed by binding to and disruption of the inner membrane, whereas activity against Gram-positive bacteria, in addition to electrostatic attraction to the exposed lipoteichoic acids, requires an ability to more deeply insert in the membrane environment, which is favoured with Arg residues and is facilitated in the presence of a Trp residue. Knowledge on the mechanism of action of these antimicrobial peptides provides information that assists in the design of antimicrobials with higher efficacy and broader spectra of action, but also on the design of peptides with higher specificity if required.
Publisher: Wiley
Date: 26-08-2013
Abstract: Because of their high activity against microorganisms and low cytotoxicity, cationic antimicrobial peptides (AMPs) have been explored as the next generation of antibiotics. Although they have common structural features, the modes of action of AMPs are extensively debated, and a single mechanism does not explain the activity of all AMPs reported so far. Here we investigated the mechanism of action of Sub3, an AMP previously designed and optimised from high-throughput screening with bactenecin as the template. Sub3 has potent activity against Gram-negative and Gram-positive bacteria as well as against fungi, but its mechanism of action has remained elusive. By using AFM imaging, ζ potential, flow cytometry and fluorescence methodologies with model membranes and bacterial cells, we found that, although the mechanism of action involves membrane targeting, Sub3 internalises inside bacteria at lethal concentrations without permeabilising the membrane, thus suggesting that its antimicrobial activity might involve both the membrane and intracellular targets. In addition, we found that Sub3 can be internalised into human cells without being toxic. As some bacteria are able to survive intracellularly and consequently evade host defences and antibiotic treatment, our findings suggest that Sub3 could be useful as an intracellular antimicrobial agent for infections that are notoriously difficult to treat.
Publisher: Hindawi Limited
Date: 2012
DOI: 10.1155/2012/460702
Abstract: The increasing bacteria resistance to conventional antibiotics has led to the need for alternative therapies. Being part of the human innate defence system and with a broad spectrum of activity against bacteria, viruses, protozoa, and cancer cells, antimicrobial peptides (AMPs) are a very promising alternative. The mechanism of action of AMPs seems to broadly correlate with their ability to target the bacterial cell membrane. To understand and improve their effect, it is of major importance to unravel their mechanism of action and, in particular, to understand the peptide-membrane binding. Several biophysical techniques such as fluorescence spectroscopy, circular dichroism, zeta potential determination, and atomic force microscopy can be used to achieve this goal. Characteristics of AMPs-membranes interactions and the use of these biophysical techniques will be discussed.
Location: Portugal
No related grants have been discovered for Inês Torcato.