Affiliation:
1. Center for Microbial Pathogenesis, Nationwide Children's Hospital, Columbus, Ohio, USA
2. Department of Pediatrics, The Ohio State University, Columbus, Ohio, USA
Abstract
ABSTRACT
Adherence to host surfaces is often mediated by bacterial binding to surface carbohydrates. Although it is widely appreciated that some bacterial species express glycosidases, previous studies have not considered whether bacteria bind to multiple carbohydrates within host glycans as they are modified by bacterial glycosidases.
Streptococcus oralis
is a leading cause of subacute infective endocarditis. Binding to platelets is a critical step in disease; however, the mechanisms utilized by
S. oralis
remain largely undefined. Studies revealed that
S. oralis
, like
Streptococcus gordonii
and
Streptococcus sanguinis
, binds platelets via terminal sialic acid. However, unlike those organisms,
S. oralis
produces a neuraminidase, NanA, which cleaves terminal sialic acid. Further studies revealed that following NanA-dependent removal of terminal sialic acid,
S. oralis
bound exposed β-1,4-linked galactose. Adherence to both these carbohydrates required Fap1, the
S. oralis
member of the serine-rich repeat protein (SRRP) family of adhesins. Mutation of a conserved residue required for sialic acid binding by other SRRPs significantly reduced platelet binding, supporting the hypothesis that Fap1 binds this carbohydrate. The mechanism by which Fap1 contributes to β-1,4-linked galactose binding remains to be defined; however, binding may occur via additional domains of unknown function within the nonrepeat region, one of which shares some similarity with a carbohydrate binding module. This study is the first demonstration that an SRRP is required to bind β-1,4-linked galactose and the first time that one of these adhesins has been shown to be required for binding of multiple glycan receptors.
Funder
The Infectious Disease Consortium at Nationwide Children's Hospital
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
27 articles.
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