Journal of Dental Research, Vol 65, 98-104, Copyright © 1986 by International & American Associations for Dental Research Online Journals
Identification of a Streptococcus sanguis receptor for salivary agglutinins
M. R. Robinovitch, D. Malamud, B. Rosan, E. E. Golub and P. Lancy Jr
The objective of this study was to characterize a fraction from oral
streptococci containing receptor activity for salivary agglutinin
molecules. Several species and strains of streptococci were disrupted in a
Ribi press. The supernatant was nuclease-treated and subjected to
differential centrifugation. Receptor activity in the fractions was
measured by the inhibition of saliva-mediated bacterial aggregation. In
addition, bacterial strains were tested for their ability to aggregate and
to deplete saliva of agglutinin activity. Three patterns of activity were
observed: Streptococcus sanguis M5 depleted saliva of agglutinin activity
and aggregated well; Streptococcus sanguis CC5A depleted saliva of
agglutinin but did not aggregate well; and Streptococcus faecalis S-161
neither depleted saliva of agglutinin nor did it aggregate. The 105,000 g
supernatant fractions derived from Ribi-disrupted Streptococcus sanguis M5
and CC5A, but not from Streptococcus faecalis, showed dose-dependent
inhibition of saliva-mediated aggregation. This inhibitory activity was
non-dialyzable, had the same heat and trypsin sensitivity as that seen with
intact bacteria, and was not due to enzymatic digestion of the salivary
agglutinin. Iso-electric focusing revealed a single active region with a pI
of 5.5 which was clearly separated from the bulk of the bacterial proteins.
