Abstract
Group A streptococcus (Streptococcus pyogenes) is the causative agent of severe invasive infections such as necrotizing fasciitis (the so-called 'flesh eating disease') and toxic-shock syndrome. Spy 1600, a glycoside hydrolase from family 84 of the large superfamily of glycoside hydrolases, has been proposed to be a virulence factor. In the present study we show that Spy 1600 has no activity toward galactosaminides or hyaluronan, but does remove beta-O-linked N-acetylglucosamine from mammalian glycoproteins - an observation consistent with the inclusion of eukaryotic O-glycoprotein 2-acetamido-2-deoxy-beta-D-glucopyranosidases within glycoside hydrolase family 84. Proton NMR studies, structure-reactivity studies for a series of fluorinated analogues and analysis of 1,2-dideoxy-2'-methyl-alpha-D-glucopyranoso-[2,1 -d]-Delta(2') -thiazoline as a competitive inhibitor reveals that Spy 1600 uses a double-displacement mechanism involving substrate-assisted catalysis. Family 84 glycoside hydrolases are therefore comprised of both prokaryotic and eukaryotic beta-N-acetylglucosaminidases using a conserved catalytic mechanism involving substrate-assisted catalysis. Since these enzymes do not have detectable hyaluronidase activity, many family 84 glycoside hydrolases are most likely incorrectly annotated as hyaluronidases.
Original language | English |
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Pages (from-to) | 241-247 |
Number of pages | 7 |
Journal | Biochemical journal |
Volume | 399 |
DOIs | |
Publication status | Published - 15 Oct 2006 |
Keywords
- beta-N-acetylglucosaminidase (GlcNAcase)
- mammalian glycoproteins
- 1,2-dideoxy-2 '-methyl-alpha-D-glucopyranoso-[2,1-d]-Delta 2 '-thiazoline (NAG-thiazoline)
- O-glycoprotein 2-acetamido-2-deoxy-beta-D-glucopyranosidase (O-GIcNAcase)
- O-glycoprotein 2-acetamido-2-deoxy-beta-D-glucopyranoside (O-GlcNAc)
- Spy1600
- substrate-assisted catalysis
- O-GLCNACASE
- CLOSTRIDIUM-PERFRINGENS
- MECHANISM
- GLUCOSAMINIDASE
- SUBSTRATE
- IDENTIFICATION
- PARTICIPATION
- PURIFICATION
- RESIDUES
- BINDING