Impaired plasma clottability induction through fibrinogen degradation by ASP, a serine protease released fromAeromonas sobria

Abstract

Aeromonas sobria infection often advances to sepsis, in which interaction of bacterial components with plasma proteins possibly causes various disorders. This bacterium releases a serine protease (ASP), a putative virulence factor, and binds to fibrinogen. To study the ASP effect on fibrinogen, we incubated fibrinogen or plasma with ASP and investigated their clotting elicited by thrombin, which converts fibrinogen to a fibrin clot. Enzymatically active ASP retarded plasma clotting in a dose-dependent manner starting at an ASP concentration of 10 nM. ASP also retarded fibrinogen clotting at 3 nM and above, which appeared to correspond to ASP cleavage of fibrinogen at the Aα-chain. Consistent with containing serine protease activity for an ASP-specific substrate, the culture supernatant of an ASP gene-introduced strain retarded plasma and fibrinogen clotting more than that of the wild-type strain. The culture supernatant of an ASP gene-disrupted strain that releases negligible serine protease activity for the ASP-specific substrate did not affect plasma clotting. These results indicate that ASP is the main fibrinogenolytic protease released from A. sobria. Impaired plasma clottability induction through fibrinogen degradation is a new virulence activity of ASP and may contribute to hemorrhagic tendencies in sepsis caused by infection with this bacterium.

The GenusAeromonas: Taxonomy, Pathogenicity, and Infection

“…Several factors probably play important roles in this process, in addition to adhesive factors needed for step 1 that are listed under gastroenteritis. Aeromonas species elaborate a wide range of microbial proteases (metalloproteases, serine proteases, and aminopeptidases) capable of degrading complex biologic proteins present in serum and connective tissue, including albumin, fibrinogen, elastin, and collagen (107,132,136,137). Degradation of such tissues and proteins can serve as an energy source for subsequent multiplication.…”

Purification and characterization of a novel alkaline serine protease secreted by Vibrio metschnikovii

“…Fibrino(geno)lytic enzymes have been reported from food bacteria (22,23), pathogenic bacteria (24)(25)(26), mushroom (27) as well as snake venom (28,29). α-fibrinogenases are often found from snake venoms, and most of them are metalloproteases, which can cleave mainly on the Aα and less on both the Bβ and the γ chains of fibrinogen subunit chains (30,31).…”

Mapping of residues of fibrinogen cleaved by protease II of Bacillus thuringiensis var. israelensis IMV B-7465

“…[8], bacillus cereus [9], Vibrio metschnikovii [10], Aeromonas sobria [11]. Their molecular weight ranges from 30 to 60 kDa.…”

“…Their molecular weight ranges from 30 to 60 kDa. Some of them preferentially degrade the Aα-chain of fibrinogen [9,11], others are targeted to both Aα-and Bβ-chains of fibrinogen [6,8] or even all three chains of fibrinogen molecule [9]. Most of bacterial fibrinogenases cleave both fibrinogen and polymeric fibrin [10,11].…”

“…Some of them preferentially degrade the Aα-chain of fibrinogen [9,11], others are targeted to both Aα-and Bβ-chains of fibrinogen [6,8] or even all three chains of fibrinogen molecule [9]. Most of bacterial fibrinogenases cleave both fibrinogen and polymeric fibrin [10,11]. These properties allowed authors to conclude the potential anti-thrombotic use of the enzymes in peptide-based cardiovascular drug development [7][8][9]12].…”