title: Photoinactivation of Gram positive and Gram negative bacteria with the antimicrobial peptide (KLAKLAK)(2) conjugated to the hydrophilic photosensitizer eosin Y.
abstract: We test the hypothesis that the antimicrobial peptide (KLAKLAK)(2) enhances the photodynamic activity of the photosensitizer eosin Y upon conjugation. The conjugate eosin-(KLAKLAK)(2) was obtained by solid-phase peptide synthesis. Photoinactivation assays were performed against the Gram-negative bacteria  Escherichia coli ,  Pseudomonas aeruginosa , and multidrug resistant  Acinetobacter baumannii  AYE, as well as the Gram-positive bacteria  Staphylococcus aureus , and  Staphylococcus epidermidis . Partitioning assays were performed with  E. coli  and  S. aureus . Photohemolysis and photokilling assays were also performed to assess the photodynamic activity of the conjugate toward mammalian cells. Eosin-(KLAKLAK)(2) photoinactivates 99.999% of 10(8) CFU/mL of most bacteria tested at a concentration of 1 μM or below. In contrast, neither eosin Y nor (KLAKLAK)(2) cause any significant photoinactivation under similar conditions. The increase in photodynamic activity of the photosensitizer conferred by the antimicrobial peptide is in part due to the fact that (KLAKLAK)(2) promotes the association of eosin Y to bacteria. Eosin-(KLAKLAK)(2) does not significantly associate with red blood cells or the cultured mammalian cell lines HaCaT, COS-7, and COLO 316. Consequently, little photodamage or photokilling is observed with these cells under conditions for which bacterial photoinactivation is achieved. The peptide (KLAKLAK)(2) therefore significantly enhances the photodynamic activity of eosin Y toward both Gram-positive and Gram-negative bacteria while interacting minimally with human cells. Overall, our results suggest that antimicrobial peptides such as (KLAKLAK)(2) might serve as attractive agents that can target photosensitizers to bacteria specifically.
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA.
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Johnson
authors.forename: Nandhini
authors.initials: N
authors.lastname: Muthukrishnan
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Pellois
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D002460:Cell Line; D004801:Eosine Yellowish-(YS) / Q000737:chemistry / Q000494:pharmacology*; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000528:radiation effects; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy; D006094:Gram-Positive Bacteria / Q000187:drug effects* / Q000528:radiation effects; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology*; D017319:Photosensitizing Agents / Q000737:chemistry / Q000494:pharmacology*; D060327:Solid-Phase Synthesis Techniques
chemical_list: D000900:Anti-Bacterial Agents; D036341:Intercellular Signaling Peptides and Proteins; C535058:KLA peptide; D010455:Peptides; D017319:Photosensitizing Agents; D004801:Eosine Yellowish-(YS)