@article{Khara:2016:jac/dkw107,
author = {Khara, JS and Priestman, M and Uhia, I and Hamilton, MS and Krishnan, N and Wang, Y and Yang, YY and Langford, PR and Newton, SM and Robertson, BD and Ee, PLR},
doi = {jac/dkw107},
journal = {Journal of Antimicrobial Chemotherapy},
pages = {2181--2191},
title = {Unnatural amino acid analogues of membrane-active helical peptides with anti-mycobacterial activity and improved stability},
url = {http://dx.doi.org/10.1093/jac/dkw107},
volume = {71},
year = {2016}
}

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TY  - JOUR
AB  - Objectives The emergence of MDR-TB, coupled with shrinking antibiotic pipelines, has increased demands for new antimicrobials with novel mechanisms of action. Antimicrobial peptides have increasingly been explored as promising alternatives to antibiotics, but their inherent poor in vivo stability remains an impediment to their clinical utility. We therefore systematically evaluated unnatural amino acid-modified peptides to design analogues with enhanced anti-mycobacterial activities.Methods Anti-mycobacterial activities were evaluated in vitro and intracellularly against drug-susceptible and MDR isolates of Mycobacterium tuberculosis using MIC, killing efficacy and intracellular growth inhibition studies. Toxicity profiles were assessed against mammalian cells to verify cell selectivity. Anti-mycobacterial mechanisms were investigated using microfluidic live-cell imaging with time-lapse fluorescence microscopy and confocal laser-scanning microscopy.Results Unnatural amino acid incorporation was well tolerated without an appreciable effect on toxicity profiles and secondary conformations of the synthetic peptides. The modified peptides also withstood proteolytic digestion by trypsin. The all D-amino acid peptide, i(llkk)2i (II-D), displayed superior activity against all six mycobacterial strains tested, with a 4-fold increase in selectivity index as compared with the unmodified L-amino acid peptide in broth. II-D effectively reduced the intracellular bacterial burden of both drug-susceptible and MDR clinical isolates of M. tuberculosis after 4 days of treatment. Live-cell imaging studies demonstrated that II-D permeabilizes the mycobacterial membrane, while confocal microscopy revealed that II-D not only permeates the cell membrane, but also accumulates within the cytoplasm.Conclusions Unnatural amino acid modifications not only decreased the susceptibility of peptides to proteases, but also enhanced mycobacterial selectivity.
AU  - Khara,JS
AU  - Priestman,M
AU  - Uhia,I
AU  - Hamilton,MS
AU  - Krishnan,N
AU  - Wang,Y
AU  - Yang,YY
AU  - Langford,PR
AU  - Newton,SM
AU  - Robertson,BD
AU  - Ee,PLR
DO  - jac/dkw107
EP  - 2191
PY  - 2016///
SN  - 1460-2091
SP  - 2181
TI  - Unnatural amino acid analogues of membrane-active helical peptides with anti-mycobacterial activity and improved stability
T2  - Journal of Antimicrobial Chemotherapy
UR  - http://dx.doi.org/10.1093/jac/dkw107
UR  - http://hdl.handle.net/10044/1/29967
VL  - 71
ER  - 

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