Identification of photolabile outer membrane proteins of Porphyromonas gingivalis

As the prevalence of antibiotic-resistant strains of bacteria increases, no vel ways of treating infections need to be developed. This is particularly pertinent with respect to the periodontal diseases-the most common chronic bacterial infections of man, The use of a photosensitizer in combination wi th red light has been demonstrated to be effective in killing several human pathogens, including the oral bacterium, Porphyromonas gingivalis, a major pathogen in periodontitis. Killing was associated with alterations in the molecular masses of several outer membrane and plasma membrane proteins and these may be therapeutic targets for photodynamic therapy and other antimi crobial approaches. To identify these photolabile proteins, we have used a panel of monoclonal antibodies raised to whole P. gingivalis. A number of t he antibodies recognized various photolabile proteins. Using a combination of Western blotting and protein sequencing the predominant photolabile prot eins in P. gingivalis have been identified as the major secreted/cell surfa ce proteases - Lys and Arg gingipain.