Immobilization and orientation‐dependent activity of a naturally occurring antimicrobial peptide

Abstract

A naturally occurring antimicrobial peptide, SMAP-29, was synthesized with an n-terminal or c-terminal cysteine, termed c_SMAP and SMAP_c, respectively, for site-directed immobilization to superparamagnetic beads. Immobilized SMAP orientation-dependent activity was probed against multiple bacteria of clinical interest including Acinetobacter baumannii, Pseudomonas aeruginosa, Bacillus anthracis sterne and Staphylococcus aureus. A kinetic microplate assay was employed to reveal both concentration and time-dependent activity for elucidation of minimum bactericidal concentration (MBC) and sub-lethal effects. Immobilized SMAP activity was equivalent or reduced compared with soluble SMAP_c and c_SMAP regardless of immobilization orientation, with only one exception. A comparison of immobilized SMAP_c and c_SMAP activity revealed a bacteria-specific potency dependent on immobilization orientation, which was contrary to that seen in solution, wherein SMAP_c was more potent against all bacteria than c_SMAP. Sub-MBC kinetic studies displayed the influence of peptide exposure to the cells with multiple bacteria exhibiting increased susceptibility and efficacy at lower concentrations upon extended exposure (i.e. MBC enhancement). For instances in which complete killing was not achieved, two predominant effects were evident: retardation of growth rate and an increased lag phase. Both effects, seen independently and concomitantly, indicate some degree of induced cellular damage that can serve as a predictor toward eventual cell death. SMAP_c immobilized on glass through standard silanization chemistry was also investigated to ascertain the influence of substrate on activity against select bacteria.

Evaluation of free or anchored antimicrobial peptides as candidates for the prevention of orthopaedic device‐related infections

“…The streptavidin/biotin-based anchoring method, which approaches the strength of a covalent bond [79], was selected as being a facile and straightforward procedure, suitable for obtaining a proof-of-concept demonstration of peptide efficacy on immobilization [80]. In our study, peptides were tethered via the N-terminus as this facilitated the biotinylation procedure, also given the reported efficacy of several N-terminally immobilized α-helical AMPs [11,18,20]. In our hands, immobilization of biotinylated peptides on streptavidin-functionalized resin beads led to a highly stable conjugate, as bactericidal activity from free peptide was not detected in the resin supernatants, even after a month of storage.…”

“…Given their abundance in nature and their relatively easy chemical production with respect to other structural classes, native peptide sequences have been exploited as templates for numerous synthetic helical AMPs with optimized structural parameters to enhance antimicrobial potency and selectivity [16,17]. As their killing mechanism does not require internalization by target bacteria, α-helical AMPs may retain activity upon immobilization, which may render them suitable for the development of antimicrobial surfaces [18][19][20].…”

Peptide-Carbon Quantum Dots conjugate, Derived from Human Retinoic Acid Receptor Responder Protein 2, against Antibiotic-Resistant Gram Positive and Gram Negative Pathogenic Bacteria

“…The pH (Low) Insertion Peptides (pHLIP peptides (low pH-dependent)) were shown to transform between three states, from unstructured highly-soluble to α-helix transmembrane state [46]. The naturally-occurring SMAP-29 peptide was shown to exhibit different antibacterial activities associated with its orientation when it was immobilized on magnetic beads [47]. Novicidin is an example of peptides that form a stabilized helix inside the lipid membrane [48].…”

Defensin-Like Peptides and Their Antimicrobial Activity in Free-Form and Immobilized on Material Surfaces

“…The relatively high MIC of C-terminus-immobilized AMPs is likely related to the inhibition of membrane interaction [51]. However, according to the literature reporting the antimicrobial activity dependence of the orientation difference between N-terminus and C-terminus-immobilized peptides, there is also a cell-dependent potency, which indicates that the mode of action of AMPs is not only dependent on their own characteristics but also on the characteristics of the targeted microorganism [103]. Another important parameter is the position of the cationic amino acids.…”