Characterization of EmpA protease in Vibrio anguillarum M3

Abstract

EmpA is an extracellular metalloprotease secreted by Vibrio anguillarum. For better understanding its role in the pathogenicity of V. anguillarum strain M3, empA insertion mutant was constructed. In the mutant it decreased in extracellular proteolytic activity, swarming motility, hemolytic activity and virulence on turbot (Scophthalmus maximus). Significant decline (by 5-fold) of extracellular proteolytic activity and similar growth curve between mutant and wild type strains indicated that EmpA was the major extracellular protease of M3. LD 50 of mutant increased by 38-fold compared with wild type. No pro-EmpA was detected in the supernatant of culture, indicating that EmpA autolyzed to mature protein after 24 h. Secretion of EmpA in M3 was similar to that in NB10 strain. Attenuated virulence of mutant was similar to that of M93Sm strain. It was demonstrated that specific operation of EmpA was different from that in previous studies and EmpA contributed to the swarming motility and hemolytic activity in V. anguillarum strain M3. The results provides insight into understanding the function of EmpA and its potential application in vaccine development.

Impact of mucin, bile salts and cholesterol on the virulence of Vibrio anguillarum towards gnotobiotic sea bass (Dicentrarchus labrax) larvae

“…2). The extracellular metalloprotease EmpA has been shown to account for nearly 90% of the total extracellular proteolytic activity of V. anguillarum (Han et al, 2011). Therefore, to further confirm our results, we determined the impact of the host factors on the expression of empA.…”

A comprehensive review of Vibrio (Listonella) anguillarum: ecology, pathology and prevention

“…The expression of emp A zinc metalloprotease by V. anguillarum in a host results in higher colonization yields, stronger growth rate, as well as increased invasion and survival by the pathogen which ultimately encourages an increase in host mortality rates (Denkin & Nelson ); recent data suggest that emp A functionality also contributes to stronger motility and haemolytic activity but the subject requires further verification (Han et al . ). Recently, the gene mlt D was determined to encode for a putative membrane‐bound lytic murein transglycosylase D protein which is involved in haemolysis, phospholipase, gelatinase and diastase activities and is believed to be linked to V. anguillarum virulence (Xu et al .…”

Secretion Systems in Gram-Negative Bacterial Fish Pathogens

“…EmpA and PrtV belong to the M4 and M6 family of peptidases, respectively, and are translated in inactive form which passes through a maturation process involving proteolytic cleavages during secretion through the T2SS ( Milton et al, 1992 ; Staroscik et al, 2005 ; Zhang et al, 2006 ; Varina et al, 2008 ; Mo et al, 2010 ; Rompikuntal et al, 2015 ). Besides its proteolytic activity, EmpA activates hemolysins promoting disruption of red blood cells in fish ( Han et al, 2011 ). PrtV contains gelatinase, protease and glycosidase activity, and a prtV mutant of V. anguillarum strain show reduced infection, growth and hemolytic activity in turbot and turbot cell lines ( Mo et al, 2010 ).…”