7 research outputs found
Development of a Peptide Antagonist against <i>fsr</i> Quorum Sensing of <i>Enterococcus faecalis</i>
<i>Enterococcus faecalis fsr</i> quorum sensing
(QS)
involves an 11-residue cyclic peptide named gelatinase biosynthesis-activating
pheromone (GBAP) that autoinduces two pathogenicity-related extracellular
proteases in a cell density-dependent fashion. To identify anti-pathogenic
agents that target <i>fsr</i> QS signaling, peptide antagonists
of GBAP were created by our unique drug design approach based on reverse
alanine scanning. First of all, a receptor-binding scaffold (RBS),
[Ala<sup>4,5,6,8,9,11</sup>]Z-GBAP, was created, in which all amino
acids within the ring region of GBAP, except for two essential aromatic
residues, were substituted to alanine. Next, the substituted alanine
residues were changed back to the original amino acid one by one,
permitting selection of those peptide combinations exhibiting increased
antagonist activity. After three cycles of this reverse alanine scan,
[Ala<sup>5,9,11</sup>]Z-GBAP was obtained as a maximally reverted
peptide (MRP) holding the strongest antagonist activity. Then, the
fifth residue in MRP, which is one of the critical residues to determine
agonist/antagonist activity, was further modified by substituting
with different types of amino acids including unnatural amino acids.
As a result, [Tyr(Bzl)<sup>5</sup>, Ala<sup>9,11</sup>]Z-GBAP, named
ZBzl-YAA5911, showed the strongest antagonist activity [IC<sub>50</sub> = 26.2 nM and <i>K</i><sub>d</sub> against GBAP receptor
(FsrC) = 39.4 nM]. <i>In vivo</i> efficacy of this peptide
was assessed with an aphakic rabbit endophthalmitis model. ZBzl-YAA5911
suppressed the translocation of <i>E. faecalis</i> from
the aqueous humor into the vitreous cavity by more than 1 order of
magnitude and significantly reduced retinal damage. We propose that
ZBzl-YAA5911 or its derivatives would be useful as anti-infective
agents to attenuate virulence expression in this opportunistic pathogen