Dj. Smith et al., PURIFICATION AND ANTIGENICITY OF A NOVEL GLUCAN-BINDING PROTEIN OF STREPTOCOCCUS-MUTANS, Infection and immunity, 62(6), 1994, pp. 2545-2552
A novel glucan-binding protein (GBP) having an apparent molecular mass
of 59 kDa (GBP(59)) has been purified from Streptococcus mutans SJ by
a combination of affinity chromatography on alpha-1,6-linked glucan,
gel filtration chromatography, and ion-exchange chromatography. GBP(59
) was distinct from the quantitatively predominant S. mutans GBP (GBP(
74)) on the basis of size, elution position in a salt gradient, and an
tigenicity. Rat antisera to purified GBP(59) and GBP(74) did not cross
-react. GBP(59) is apparently immunogenic in humans, since immunoglobu
lin A (IgA) antibody in 20 of 24 adult parotid saliva samples was show
n to react with GBP(59) in an enzyme-linked immunosorbent assay. The g
lucan-binding activity of GBP(59) was confirmed by anti-GBP(59) immuno
gold labelling of Sephadex G-50 that had been preincubated with S. mut
ans culture supernatant. GBP(59) could be detected in culture supernat
ants of all laboratory strains of S. mutans (e.g., Ingbritt), as well
as all strains of S. mutans that had been recently isolated from young
children. GBP(59) was often the only component in protease inhibitor-
containing 4-h S. mutans culture supernatants that reacted with human
parotid salivary IgA antibody in Western blot (immunoblot) analyses. T
hese studies suggest that GBP(59) is a structurally and antigenically
distinct S. mutans GBP that can elicit significant levels of salivary
IgA antibody in humans.