Premium
Effective antimicrobial activity of Cbf‐K 16 and Cbf‐A 7 A 13 against NDM‐1‐carrying Escherichia coli by DNA binding after penetrating the cytoplasmic membrane in vitro
Author(s) -
Hao Qingru,
Wang Hui,
Wang Jing,
Dou Jie,
Zhang Min,
Zhou Weidong,
Zhou Changlin
Publication year - 2013
Publication title -
journal of peptide science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 66
eISSN - 1099-1387
pISSN - 1075-2617
DOI - 10.1002/psc.2488
Subject(s) - escherichia coli , antimicrobial , chemistry , agarose gel electrophoresis , antimicrobial peptides , bacteria , recombinant dna , minimum inhibitory concentration , klebsiella pneumoniae , microbiology and biotechnology , dna , biology , biochemistry , gene , genetics
New Delhi metallo‐beta‐lactamase‐1(NDM‐1)‐carrying isolates, which are resistant to most clinical used antibiotics except for tigecycline and colistin, have been found worldwide. Cathelicidin‐BF (BF‐30) is found in the venom of the snake Bungarus fasciatus and exhibits broad antimicrobial activity. Cbf‐K 16 and Cbf‐A 7 A 13 were obtained by mutating Lys 16 , Ala 7 , and Ala 13 of BF‐30, respectively. To investigate their antimicrobial activities against NDM‐1 carrying bacteria, recombinant Escherichia coli BL21 (DE3)‐NDM‐1 with high NDM‐1 activity was constructed by inserting the Klebsiella pneumoniae NDM‐1 gene (GenBank accession no. HQ328085) into a pET28a vector and transforming it into E . coli BL21 (DE3). The peptides showed effective antimicrobial activities against NDM‐1‐carrying E . coli , and the minimum inhibitory concentrations of Cbf‐K 16 and Cbf‐A 7 A 13 were only 4 and 8 µg/ml, whereas those of minimum bactericidal concentrations were 8 and 16 µg/ml, respectively. A time course experiment showed that colony forming unit counts rapidly decreased, and bacteria were thoroughly eliminated within 3 and 6 h by the Cbf‐K 16 and Cbf‐A 7 A 13 treatments, respectively. The peptides penetrated the bacterial cell membrane and enabled β ‐galactosidase leakage, and caused the cytoplasmic membrane to become permeable, and finally bound to the DNA. The genomic DNA of E . coli was completely unable to migrate on an agarose gel after Cbf‐K 16 treatment (8 µg/ml). These data demonstrated that Cbf‐K 16 and Cbf‐A 7 A 13 possess effective antimicrobial activity against drug‐resistant strains, including NDM‐1 carrying E . coli BL21 (DE3)‐NDM‐1, by binding to DNA after penetrating the cytoplasmic membrane in vitro , which may have potential therapeutic value for the treatment of NDM‐1‐carrying bacterial infections. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.