Designed Coiled-Coil Peptides Inhibit the Type Three Secretion System of Enteropathogenic Escherichia coli

Abstract

BackgroundEnteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli (EHEC) are two categories of E. coli strains associated with human disease. A major virulence factor of both pathotypes is the expression of a type three secretion system (TTSS), responsible for their ability to adhere to gut mucosa causing a characteristic attaching and effacing lesion (A/E). The TTSS translocates effector proteins directly into the host cell that subvert mammalian cell biochemistry.Methods/Principal FindingsWe examined synthetic peptides designed to inhibit the TTSS. CoilA and CoilB peptides, both representing coiled-coil regions of the translocator protein EspA, and CoilD peptide, corresponding to a coiled–coil region of the needle protein EscF, were effective in inhibiting the TTSS dependent hemolysis of red blood cells by the EPEC E2348/69 strain. CoilA and CoilB peptides also reduced the formation of actin pedestals by the same strain in HEp-2 cells and impaired the TTSS-mediated protein translocation into the epithelial cell. Interestingly, CoilA and CoilB were able to block EspA assembly, destabilizing the TTSS and thereby Tir translocation. This blockage of EspA polymerization by CoilA or CoilB peptides, also inhibited the correct delivery of EspB and EspD as detected by immunoblotting. Interestingly, electron microscopy of bacteria incubated with the CoilA peptide showed a reduction of the length of EspA filaments.ConclusionsOur data indicate that coiled-coil peptides can prevent the assembly and thus the functionality of the TTSS apparatus and suggest that these peptides could provide an attractive tool to block EPEC and EHEC pathogenesis.

Anti-biofilm, anti-hemolysis, and anti-virulence activities of black pepper, cananga, myrrh oils, and nerolidol against Staphylococcus aureus

“…Red blood hemolysis assay Hemolysis was quantified as described previously with some modification (Larzábal et al 2010). Human red blood cell lysis efficacies were measured using whole cultures of S. aureus grown in the presence of the essential oils or compounds.…”

Targeting the type III secretion system to treat bacterial infections

“…However, the overall quantity of needle subunits was unchanged, suggesting that the primary effect of INP0400 may be to inhibit subunit secretion or assembly of the S. flexneri T3SS needle. 15-amino acid peptides, CoilA and CoilB, to mimic and block the coiled-coil domain of the EPEC filament protein, EspA [69,70]. This 30-amino acid coiled-coil domain is essential for translocon assembly.…”

“…Strains lacking intimin demonstrate decreased colonization and virulence during infection [79], making the intimin--Tir interaction an excellent potential target. Larzábal et al engineered a synthetic peptide to disrupt the intimin-binding domain of Tir, although its effects on T3S and virulence were not pursued [69].…”

Flavone Reduces the Production of Virulence Factors, Staphyloxanthin and α-Hemolysin, in Staphylococcus aureus

“…Hemolysis analysis was modified from the previous method [10]. The lysis efficacy of human red blood cells was measured with whole cultures of S. aureus grown in the presence of flavonoids.…”