Burkholderia pseudomallei (BP)is causative agent of melioidosis, a disease endemic in tropical area such
as in Southeast Asia and Northern Australia. Previous reports showed that
cathelicidin-derived peptides LL-37 and its truncated LL-31 could inhibit
growth of BP and LL-31 showed better activity than
LL-37. This study aimed to elucidate the mechanism of action that allow better
killing activity of LL-31 when comparing to LL-37 on live BPand
membrane model, LL-31 showed better killing activities on BP than LL-37.
In LPS-binding assay, LL-31 exhibited 9 to 14%
displacement of PMB-BY whereas LL-37 exhibited only 3 to 5%. For the membrane
permeabilization study, LL-31 showed slightly stronger in both outer and inner
membrane permeation than LL-37, as observed with NPN-uptake assay and SYTOX®
green influx in both cases. In addition, testing membrane fluidity by change in
TMA-DPH and DPH anisotropy, results of this study showed that LL-37 could induce
a change in membrane fluidity more effective than that of LL-31 through
observed change in TMA-DPH anisotropy and DPH anisotropy. The leakage activity
of ANTS/DPX liposome induced by LL-37 and LL-37 were about 55% and 50%,
respectively. The hydrophobicity (H) and hydrophobic moment (µH) of LL-31 were
more than those of LL-37. Taken together, we demonstrate better activity of
LL-31 was through its better permeabilizing ability due to more hydrophobic
content.