A survey for phosphoglucose isomerase with lysyl aminopeptidase activity in Vibrionaceae and non-Vibrio pathogens

Phosphoglucose isomerase (PGI) with a novel lysyl aminopeptidase (LysAP) activity was recently purified and characterized from Vibrio vulnificus. We showed that it cleaves the amino-terminal lysyl residue from des-Arg10-kallidin to produce des-Arg9-bradykinin, suggesting that it plays a role in virulence. A survey was conducted to determine the presence of this potential virulence-enhancing enzyme among twenty-three halotolerant human and fish pathogens from eleven species within the Vibrionaceae family, including V. vulnificus, V. parahaemolyticus, V. cholerae, Aeromonas hydrophila, and Plesiomonas shigelloides. In addition, fourteen species of non-Vibrionaceae pathogens were screened for LysAP activity. Cell lysates were partially purified by anion exchange chromatography and fractions were screened for LysAP and isomerase activities. PGI-LysAP activity was detected in chromatographic fractions from all the Vibrio species tested, but was not detected in any of the non-Vibrionaceae pathogens. Levels of isomerase and LysAP activity correlated (R2=0.92) for nine strains of V. vulnificus. Since the Vibrionaceae represent an important family of human and fish pathogens, our identification of PGI-LysAP activity in a broad array of vibrios may lead to the development of improved analytical methods for their identification as well as interventions to reduce the high morbidity and mortality associated with some Vibrionaceae infections in clinical, veterinary, and aquaculture settings.