Structural and antimicrobial properties of human pre-elafin/trappin-2 and derived peptides against Pseudomonas aeruginosa

Abstract

BackgroundPre-elafin/trappin-2 is a human innate defense molecule initially described as a potent inhibitor of neutrophil elastase. The full-length protein as well as the N-terminal "cementoin" and C-terminal "elafin" domains were also shown to possess broad antimicrobial activity, namely against the opportunistic pathogen P. aeruginosa. The mode of action of these peptides has, however, yet to be fully elucidated. Both domains of pre-elafin/trappin-2 are polycationic, but only the structure of the elafin domain is currently known. The aim of the present study was to determine the secondary structures of the cementoin domain and to characterize the antibacterial properties of these peptides against P. aeruginosa.ResultsWe show here that the cementoin domain adopts an α-helical conformation both by circular dichroism and nuclear magnetic resonance analyses in the presence of membrane mimetics, a characteristic shared with a large number of linear polycationic antimicrobial peptides. However, pre-elafin/trappin-2 and its domains display only weak lytic properties, as assessed by scanning electron micrography, outer and inner membrane depolarization studies with P. aeruginosa and leakage of liposome-entrapped calcein. Confocal microscopy of fluorescein-labeled pre-elafin/trappin-2 suggests that this protein possesses the ability to translocate across membranes. This correlates with the finding that pre-elafin/trappin-2 and elafin bind to DNA in vitro and attenuate the expression of some P. aeruginosa virulence factors, namely the biofilm formation and the secretion of pyoverdine.ConclusionsThe N-terminal cementoin domain adopts α-helical secondary structures in a membrane mimetic environment, which is common in antimicrobial peptides. However, unlike numerous linear polycationic antimicrobial peptides, membrane disruption does not appear to be the main function of either cementoin, elafin or full-length pre-elafin/trappin-2 against P. aeruginosa. Our results rather suggest that pre-elafin/trappin-2 and elafin, but not cementoin, possess the ability to modulate the expression of some P.aeruginosa virulence factors, possibly through acting on intracellular targets.

Alarm anti‐protease trappin‐2 negatively correlates with proinflammatory cytokines in patients with periodontitis

“…Salivary levels of trappin‐2 decreased with severity of periodontal disease and negatively correlated with proinflammatory cytokine IL‐1β. The present findings are also in support of earlier studies demonstrating association between reduced trappin‐2 levels and other chronic inflammatory diseases …”

“…Although elafin is a potent antiprotease, there is considerable evidence in the literature that it is prone to be inactivated by proteolytic cleavage due to excessive neutrophil elastase activity, which may hamper its therapeutic capacity in vivo . Additionally, trappin‐2 has been shown to possess greater antibacterial activity than elafin …”

Elafin Reverses Pulmonary Hypertension via Caveolin-1–Dependent Bone Morphogenetic Protein Signaling

“…The polycationic nature of elafin allows it to permeate, and accumulate within the phospholipid bilayer (47). In this hydrophobic environment the N-terminus of elafin forms an a-helix that can serve as a membrane anchor (48).…”

Anti-HIV-1 Activity of Elafin Depends on Its Nuclear Localization and Altered Innate Immune Activation in Female Genital Epithelial Cells

“…Several mechanisms of Tr/E antimicrobial activity have been proposed, including their direct interaction with microbial cell membrane due to the cationic nature of these molecules [31], bacterial opsonization [32], and binding to bacterial DNA [33]. Tr/E were also shown to possess immunomodulatory properties [24].…”