Sialidase specificity determined by chemoselective modification of complex sialylated glycans.
Sialidases hydrolytically remove sialic acids from sialylated glycoproteins and glycolipids. Sialidases are widely distributed in nature and sialidase-mediated desialylation is implicated in normal and pathological processes. However, mechanisms by which sialidases exert their biological effects remain obscure, in part because sialidase substrate preferences are poorly defined. Here we report the design and implementation of a sialidase substrate specificity assay based on chemoselective labeling of sialosides. We show that this assay identifies components of glycosylated substrates that contribute to sialidase specificity. We demonstrate that specificity of sialidases can depend on structure of the underlying glycan, a characteristic difficult to discern using typical sialidase assays. Moreover, we discovered that Streptococcus pneumoniae sialidase NanC strongly prefers sialosides containing the Neu5Ac form of sialic acid versus those that contain Neu5Gc. We propose using this approach to evaluate sialidase preferences for diverse potential substrates.
Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390-9185, USA.
Randy B
RB
Parker
Janet E
JE
McCombs
Jennifer J
JJ
Kohler
D001173:Arthrobacter / Q000737:chemistry / Q000201:enzymology*; D002240:Carbohydrate Sequence; D006801:Humans; D008969:Molecular Sequence Data; D009439:Neuraminidase / Q000378:metabolism*; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism*; D012486:Salmonella typhimurium / Q000737:chemistry / Q000201:enzymology*; D012794:Sialic Acids / Q000737:chemistry / Q000378:metabolism*; D013296:Streptococcus pneumoniae / Q000737:chemistry / Q000201:enzymology*; D013379:Substrate Specificity
D011134:Polysaccharides; D012794:Sialic Acids; D009439:Neuraminidase