Background: Human α-defensins (HNPs 1-3) are small cationic, amphipatic peptides with microbicidal activities. HNP-1 is the physiological target of ART1, an arginine (Arg) specific eucaryotic ribosyltransferase enzyme1. Mono ADP-ribosylation of Arg14 of HNP-1 modulates its biological activities2. Bacterial exotoxins like Cholera Toxin (CT) by Vibrio cholerae, Heat Labile Enterotoxin (LT1) by Escherichia coli and Exoenzyme S (ExoS) by Pseudomonas aeruginosa are arginine ADP-ribosyltransferase enzymes that alter cell functions by modifying protein targets. Objectives: 1. Evaluate the ADP ribosylation of HNP-1 by CT, LT1 and ExoS. 2. Purify modified peptides and identify the ADP-ribosylated Arg. Methods: ADP-ribosylation of HNP-1 will be evaluated with biotinilated NAD by western blot. Purification of modified peptides will be performed by reverse phase HPLC. Identification of modification will be performed by Maldi-Toff analysis. Results: 1. CT and LT1 are effective in ADP-ribosylating HNP-1 as equal as the well known activity of ART1. On the other hand ExoS does not recognize HNP-1 as substrate. 2. Ongoing experiments are purifications and characterization of modified peptides by reverse-phase HPLC and Maldi-Toff analysis. Conclusions: 1. The different ADP-ribosylating activities displayed by CT, LT1 and ExoS on HNP-1 might be explained with differences in microbial pathogenesis, as the toxins released by V. cholerae and E. coli are involved in the early stages of infections, during the interactions with surface epithelial cells, while ExoS by P. aeruginosa is active during blood dissemination, when the pathogen has already overcome epithelial barrier. References: 1 Balducci et al., 1999, Am J Respir Cell Mol Biol, 21, 337-46 2 Paone et al., 2006, J Biol Chem, 281, 17054-60
ANTIMICROBIAL PEPTIDES ARE TARGETS FOR BACTERIAL ADP-RIBOSYLTRANSFERASE ENZYMES
BALDUCCI, Enrico
2009-01-01
Abstract
Background: Human α-defensins (HNPs 1-3) are small cationic, amphipatic peptides with microbicidal activities. HNP-1 is the physiological target of ART1, an arginine (Arg) specific eucaryotic ribosyltransferase enzyme1. Mono ADP-ribosylation of Arg14 of HNP-1 modulates its biological activities2. Bacterial exotoxins like Cholera Toxin (CT) by Vibrio cholerae, Heat Labile Enterotoxin (LT1) by Escherichia coli and Exoenzyme S (ExoS) by Pseudomonas aeruginosa are arginine ADP-ribosyltransferase enzymes that alter cell functions by modifying protein targets. Objectives: 1. Evaluate the ADP ribosylation of HNP-1 by CT, LT1 and ExoS. 2. Purify modified peptides and identify the ADP-ribosylated Arg. Methods: ADP-ribosylation of HNP-1 will be evaluated with biotinilated NAD by western blot. Purification of modified peptides will be performed by reverse phase HPLC. Identification of modification will be performed by Maldi-Toff analysis. Results: 1. CT and LT1 are effective in ADP-ribosylating HNP-1 as equal as the well known activity of ART1. On the other hand ExoS does not recognize HNP-1 as substrate. 2. Ongoing experiments are purifications and characterization of modified peptides by reverse-phase HPLC and Maldi-Toff analysis. Conclusions: 1. The different ADP-ribosylating activities displayed by CT, LT1 and ExoS on HNP-1 might be explained with differences in microbial pathogenesis, as the toxins released by V. cholerae and E. coli are involved in the early stages of infections, during the interactions with surface epithelial cells, while ExoS by P. aeruginosa is active during blood dissemination, when the pathogen has already overcome epithelial barrier. References: 1 Balducci et al., 1999, Am J Respir Cell Mol Biol, 21, 337-46 2 Paone et al., 2006, J Biol Chem, 281, 17054-60I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.