Molecular identification of hyaluronate lyase, not hyaluronidase, as an intrinsic hyaluronan-degrading enzyme in Clostridium perfringens

Abstract Clostridium perfringens, an opportunistic pathogen in the human intestine, causes gas gangrene by producing various toxins. A clostridial enzyme degrading the host extracellular matrix hyaluronan (HA) has been considered a critical virulence factor as mu-toxin hyaluronidases including endo-β-N-acetylglucosaminidases (Nags). Here we show that, distinct from Nags, hyaluronate lyase (HysA) is an intrinsic HA-degrading enzyme. C. perfringens (ATCC 13124) was found to assimilate host-derived extracellular mucosubstances, HA and mucin, which induced expression of the HA-related genetic cluster, including hysA, but repressed nag genes. The recombinant C. perfringens HysA showed an HA-degrading activity toward HA through β-elimination reaction. The HA-degrading enzyme in the culture supernatant of C. perfringens exhibited the lyase activity and was identical to the recombinant HysA on the native-PAGE gel, followed by activity straining. These results demonstrated that the intrinsic HA-degrading enzyme of C. perfringens is hyaluronate lyase HysA, but not hyaluronidases NagH, NagJ, and NagK.