title: Molecular targets of antimicrobial photodynamic therapy identified by a proteomic approach.
abstract: Antimicrobial photodynamic therapy (PDT) is a promising tool to combat antibiotic-resistant bacterial infections. During PDT, bacteria are killed by reactive oxygen species generated by a visible light absorbing photosensitizer (PS). We used a classical proteomic approach that included two-dimensional gel electrophoresis and mass spectrometry analysis, to identify some proteins of Staphylococcus aureus that are damaged during PDT with the cationic PS meso-tetra-4-N-methyl pyridyl porphine (T4). Suspensions of S. aureus cells were incubated with selected T4 concentrations and irradiated with doses of blue light that reduced the survival to about 60% or 1%. Proteomics analyses of a membrane proteins enriched fraction revealed that these sub-lethal PDT treatments affected the expression of several functional classes of proteins, and that this damage is selective. Most of these proteins were found to be involved in metabolic activities, in oxidative stress response, in cell division and in the uptake of sugar. Subsequent analyses revealed that PDT treatments delayed the growth and considerably reduced the glucose consumption capacity of S. aureus cells. This investigation provides new insights towards the characterization of PDT induced damage and mechanism of bacterial killing using, for the first time, a proteomic approach.
authors.affiliation: Department of Biology, University of Padova, Via U. Bassi 58/B, 35128 Padova, Italy. ryan.dosselli@unipd.it
authors.forename: Ryan
authors.initials: R
authors.lastname: Dosselli
authors.forename: Renato
authors.initials: R
authors.lastname: Millioni
authors.forename: Lucia
authors.initials: L
authors.lastname: Puricelli
authors.forename: Paolo
authors.initials: P
authors.lastname: Tessari
authors.forename: Giorgio
authors.initials: G
authors.lastname: Arrigoni
authors.forename: Cinzia
authors.initials: C
authors.lastname: Franchin
authors.forename: Anna
authors.initials: A
authors.lastname: Segalla
authors.forename: Enrico
authors.initials: E
authors.lastname: Teardo
authors.forename: Elena
authors.initials: E
authors.lastname: Reddi
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D024881:Drug Resistance, Bacterial / Q000187:drug effects / Q000528:radiation effects; D018384:Oxidative Stress / Q000187:drug effects / Q000528:radiation effects; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000494:pharmacology*; D011166:Porphyrins / Q000494:pharmacology*; D040901:Proteomics / Q000379:methods; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000378:metabolism; D013211:Staphylococcus aureus / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D017319:Photosensitizing Agents; D011166:Porphyrins; C021096:tetra(4-N-methylpyridyl)porphine