C. Rathsam et al., THE CELL-BOUND FRUCTOSYLTRANSFERASE OF STREPTOCOCCUS-SALIVARIUS - THECARBOXYL-TERMINUS SPECIFIES ATTACHMENT IN A STREPTOCOCCUS-GORDONII MODEL SYSTEM, Journal of bacteriology, 175(14), 1993, pp. 4520-4527
The ftf gene, coding for the cell-bound beta-D-fructosyltransferase (F
TF) of Streptococcus salivarius ATCC 25975, has been analyzed, and its
deduced amino acid sequence has been compared with that of the secret
ed FTF of Streptococcus mutans and the levansucrases (SacBs) of Bacill
us species. A unique proline-rich region detected at the C terminus of
the FTF of S. salivarius preceded a hydrophobic terminal domain. This
proline-rich region was shown to possess strong homology to the produ
ct of the prgC gene from pCF10 in Enterococcus faecalis, which encodes
a pheromone-responsive protein of unknown function, as well as homolo
gy to the human proline-rich salivary protein PRP4. A series of 3'-OH
deletions of the S. salivarius ftf gene expressed in Streptococcus gor
donii Challis LGR2 showed that the C terminus was required for cell su
rface attachment in this heterologous organism, as only the complete g
ene product was cell bound. This cell-bound activity was released in t
he presence of sucrose, suggesting that the mode of attachment and rel
ease of the S. salivarius FTF in S. gordonii was similar to that in it
s native host.