Mp. Bos et al., CD66 RECEPTOR SPECIFICITY EXHIBITED BY NEISSERIAL OPA VARIANTS CONTROLLED BY PROTEIN DETERMINANTS IN CD66 N-DOMAINS, Proceedings of the National Academy of Sciences of the United Statesof America, 95(16), 1998, pp. 9584-9589
Neisseria gonorrhoeae strain MS11 is able to express 11 different opac
ity (Opa) proteins on its outer surface. A number of these Opa protein
s have been shown to function as adhesins through binding of CD66 rece
ptors present on human cells. CD66 antigens, or carcinoembryonic antig
en family members, constitute a family of glycoproteins belonging to t
he immunoglobulin superfamily. Opa variants recognize this class of re
ceptors in a differential manner such that certain Opa variants recogn
ize up to four different CD66 receptors (CD66a, -c, -d, and -e), where
as others recognize only two (CD66a and -e) or none. Ve explored the b
asis for this receptor tropism in the present study. Our data show tha
t glycoforms of CD66e and deglycosylated CD66e are recognized by gonoc
occi in an Opa-specific manner. Binding by Opa variants of recombinant
N-terminal domains of CD66 receptors expressed in Escherichia coli re
flected the adherence specificities of Opa variants to HeLa cells expr
essing native CD66 molecules. These data indicate that recognition of
CD66 receptors by Opa variants is mediated by the protein backbone of
the CD66 N-domains. Furthermore, by using chimeric constructs between
different CD66 N-domains me identified distinct binding regions on the
CD66e N-domain for specific groups of Opa variants, suggesting that t
he differential recognition of CD66 receptors by Opa variants is dicta
ted by the presence of specific binding regions on the N-domain of the
receptor.