Open AccessHuman‐β‐defensins‐1‐3 and analogs do not require proton motive force for antibacterial activity against Escherichia coli
Author(s) -
Krishnakumari Viswanatha,
Packiyanathan Kavin K.,
Nagaraj Ramakrishnan
Publication year - 2013
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/1574-6968.12242
Subject(s) - escherichia coli , antibacterial activity , chemistry , divalent , chemiosmosis , biophysics , biochemistry , stereochemistry , bacteria , biology , organic chemistry , atp synthase , enzyme , genetics , gene
Human‐β‐defensins 1‐3 ( HBD ‐1‐3) and their C‐terminal analogs Phd‐1‐3 do not show antibacterial activity against E scherichia coli in the presence of mono‐ and divalent cations. Activity of peptides was examined against E . coli pretreated with carbonyl cyanide m‐chlorophenylhydrazone ( CCCP ) and salt remedial E scherichia coli fts EX , a deletion mutant of Fts EX complex [an ATP ‐binding cassette ( ABC ) transporter protein], in the presence of Na + , Ca 2+ , and Mg 2+ . Activity was observed in the presence of Na + and Ca 2+ , although not in the presence of Mg 2+ against E . coli, when proton motive force ( PMF ) was dissipated by CCCP . The peptides exhibited antibacterial activity against E . coli fts EX even in the presence of Na + and Ca 2+ . Our results indicate that HBD ‐1‐3 and Phd‐1‐3 do not require PMF for their antibacterial activity. The absence of activity against E . coli in the presence of Na + and Ca 2+ ions is due to not only weakened electrostatic interactions with anionic membrane components, but also involvement of electrochemical gradients. However, Mg 2+ prevents electrostatic interaction of the peptides with the outer membrane resulting in loss of activity.