3 research outputs found
Drug-to-genome-to-drug, step 2 : reversing selectivity in a series of antiplasmodial compounds
Dissecting the binding interactions of teixobactin with the bacterial cell wall precursor lipid II
The prevalence of lifeāthreatening, drugāresistant microbial infections has challenged researchers to consider alternatives to currently available antibiotics. Teixobactin is a recently discovered āresistanceāproofā antimicrobial peptide that targets the bacterial cell wall precursor lipidā
II. In doing so, teixobactin exhibits potent antimicrobial activity against a wide range of Gramāpositive organisms. Herein we demonstrate that teixobactin and several structural analogues are capable of binding lipidā
II from both Gramāpositive and Gramānegative bacteria. Furthermore, we show that when combined with known outer membraneādisrupting peptides, teixobactin is active against Gramānegative organisms.</p
Genetically-Encoded Discovery of Proteolytically Stable Bicyclic Inhibitors of Morphogen NODAL
In
this manuscript, we developed a Two-fold Symmetric Linchpin (TSL) that converts
readily available phage display peptides libraries made of 20 common amino
acids to genetically-encoded libraries of bicyclic peptides displayed on phage.
TSL combines an aldehyde-reactive
group and two thiol-reactive groups; it bridges two side chains of cysteine [C]
with an N-terminal aldehyde group derived from the N-terminal serine [S],
yielding a novel bicyclic topology that lacks a free N-terminus. Phage display
libraries of SX1CX2X3X4X5X6X7C
sequences, where Xi is any
amino acids but Cys, were converted to a library of bicyclic TSL-[S]X1[C]X2X3X4X5X6X7[C]
peptides in 45 Ā± 15%
yield. Using this library and protein morphogen NODAL as a target, we
discovered bicyclic macrocycles that specifically antagonize NODAL-induced
signaling in cancer cells. At a 10 ĀµM concentration, two discovered bicyclic
peptides completely suppressed NODAL-induced phosphorylation of SMAD2 in P19
embryonic carcinoma. The TSL-[S]Y[C]KRAHKN[C]
bicycle inhibited NODAL-induced proliferation of NODAL-Tky-nu ovarian carcinoma
cells with apparent IC50 1 ĀµM. The same bicycle at 10 ĀµM concentration did not
affect the growth of the control Tky-nu cells. TSL-bicycles remained
stable over the course of the 72 hour-long assays in a serum-rich cell-culture
medium. We further observed general stability in mouse serum and in a mixture of
proteases (PronaseTM) for 33 diverse bicyclic macrocycles of
different ring sizes, amino acid sequences, and cross-linker geometries. TSL-constrained peptides expand the
previously reported repertoire of phage display bicyclic architectures formed
by cross-linking Cys side chains. We anticipate that it will aid the discovery
of proteolytically stable bicyclic inhibitors for a variety of protein targets