Mucin degradation in the human colon: production of sialidase, sialate O-acetylesterase, N-acetylneuraminate lyase, arylesterase, and glycosulfatase activities by strains of fecal bacteria

Abstract

Oligosaccharide side chains of human colonic mucins contain 0-acetylated sialic acids and glycosulfate esters. Although these substituents are considered to protect the chains agiist degradation by bacterial glycosidases, sialate O-acetylesterase, N-acetylneuraminate lyase, and glycosulfatase activities have been found in fecal extracts. To better define the source of these activities, we measured extracellular and cell-bound sialidase, sialate O-acetylesterase, N-acetylneuraminate lyase, arylesterase, and glycosulfatase activities produced by 23 isolates of human fecal bacteria grown anaerobically in a hog gastric mucin culture medium; these represented dominant populations of fecal anaerobes, facultative anaerobes, and the subset of mucin oligosaccharide-degrading bacteria. Every strain produced sialidase and high levels of arylesterase, and all but five facultative anaerobes produced sialate O-acetylesterase. Sialic acids containing 2 mol or more of O-acetyl ester per mol of sialic acid were cleaved from mucin glycoproteins more slowly by sialidases of mucin oligosaccharide-degrading stains than were sialic acids containing 1 or 0 mol, and only N-acetyland mono-O-acetylated sialic acids were recovered from enzyme digests of a mucin containing di-O-acetylated sialic acids. No detectable N-acetylneuraminate lyase activity was produced by any strain, but low activity was induced by increasing the glycoprotein-bound sialic acid concentration in the culture medium of six Escherichia coli strains. Using lactitol-6-sulfate as a substrate, we found weak glycosulfatase activity in the partially purified, concentrated enzyme mixture in the culture supernatants of four mucin oligosaccharide-degrading strains but in none of the unconcentrated culture fractions. We conclude that the presence of two or more O-acetyl groups on sialic acids inhibits enteric bacterial sialidases but that production of sialate O-acetylesterases by several populations of enteric bacteria lessens the likelihood that mucin oligosaccharide chains terminating in 0-acetylated sialic acids are protected from degradation. Sialate O-acetylesterases have a role * Corresponding author.

Post-Glycosylation Modification of Sialic Acid and Its Role in Virus Pathogenesis

“…Treatment with NaOH or NaIO4 gave slow to complete loss of hemagglutinin inhibition, presumably due to the loss of the Considering eukaryotic systems, O-acetylated Neu5Acs of colonic mucin glycoproteins from human colon cell lines are ubiquitous [37]. Corfield and co-workers showed the inhibition of B. bifidum VIII-210 sialidase activity by C 7,8, and 9 O-acetylated Neu5Ac [101] in 1992. Interestingly, the inhibitory effects were increased as amounts of O-acetyl groups increased.…”

The ability to utilize mucin affects the regulation of virulence gene expression inStreptococcus pneumoniae

“…Sialate O-acetylesterase activity was assayed as described previously (Corfield et al, 1992). Briefly, 100 mL pneumococcal cell lysate was mixed with 100 mL 5 mg mL À1 bovine submandibular gland glycoprotein (contains on average 2 mol of O-acetyl ester per mole of sialic acid) in 0.1 M triethanolamine buffer (pH 7.8).…”

“…The first stage of mucin degradation is the cleavage of the terminal sialic acid by neuraminidases because the sequential nature of degradation by glycosidases requires the initial removal of sialic acids at the outer, nonreducing end of the chain (Corfield et al, 1992). However, the activity of neuraminidases depends strongly on the type of linkage to sialic acid and O-acetylation of sialic acid.…”

“…The presence of O-acetylation of sialic acid hydroxyl groups, especially those at C7-9 of the sialic acid, hinders the activity of neuraminidases. The removal of O-acetylated sialic acids occurs at a slower rate compared to non-O-acetylated ones (Corfield et al, 1992). The limiting influence of O-acetylation can be overcome by removal of the acetyl groups by sialate O-acetylesterases.…”

De-O-Acetylation of mucin-derived sialic acids by recombinant NanS-p esterases of Escherichia coli O157:H7 strain EDL933

“…Expressing NanS, commensal non-pathogenic E. coli are able to utilize O-acetylated sialic acids as carbon sources. NanS belongs to the large family of SGNH serine proteases, which are not only found in commensal bacteria, but also in a number of pathogens that produce sialate O-acetylesterases (Corfield et al, 1992(Corfield et al, , 1993Phansopa et al, 2015). Vimr (2013) have extensively reviewed the bacterial sialometabolism and reported that many enteropathogenic E. coli strains harbor further nanS-homologs.…”