Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0014118 (endocarditis)
 15,629 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Bacterial recognition of host sialic acid-containing receptors plays an important role in microbial colonization of the human oral cavity. The sialic acid-binding adhesin of Streptococcus gordonii DL1 was previously associated with the hsa gene encoding a 203-kDa protein. The predicted protein sequence consists of an N-terminal nonrepetitive region (NR1), including a signal sequence, a relatively short serine-rich region (SR1), a second nonrepetitive region (NR2), a long serine-rich region (SR2) containing 113 dodecapeptide repeats, and a C-terminal cell wall anchoring domain. In the present study, the contributions of SR1, NR2, and SR2 to Hsa-mediated adhesion were assessed by genetic complementation. Adhesion of an hsa chromosomal deletion mutant to sialic acid-containing receptors was restored by plasmids containing hsa constructs encoding Hsa that lacked either the N- or C-terminal portion of SR2. In contrast, hsa constructs that lacked the coding sequences for SR1, NR2, or the entire SR2 region failed to restore adhesion. Surface expression of recombinant Hsa was not affected by removal of SR1, NR2, or a portion of SR2 but was greatly reduced by complete removal of SR2. Wheat germ agglutinin, a probe for Hsa-specific glycosylation, reacted with recombinant Hsa lacking SR1, NR2, or SR2 but not with recombinant Hsa lacking both SR1 and SR2. Significantly, the aggregation of human platelets by S. gordonii DL1, an interaction implicated in the pathogenesis of infective endocarditis, required the expression of hsa. Moreover, neuraminidase treatment of the platelets eliminated this interaction, further supporting the hypothesis that Hsa plays an essential role in the bacterium-platelet interaction.
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PMID:Functional analysis of the Streptococcus gordonii DL1 sialic acid-binding adhesin and its essential role in bacterial binding to platelets. 1521 30

Oral streptococci comprise a numerically prominent group of oral bacteria that occur primarily on the human tooth surface as members of the biofilm community, commonly referred to as dental plaque. These streptococci are not only causative of dental caries and are primers for colonization of periodontopathic bacteria, but also well known for their ability to colonize damaged heart valves, identified most frequently as primary etiological agents of infective endocarditis. A number of streptococcal cell surface components are known to contribute to colonization of the tooth surface including putative adhesins recognizing host sialic acid (sialic acid-binding adhesins). Interactions mediated by these adhesins include the attachment of these bacteria to saliva-coated hydroxyapatite and their adhesion to erythrocytes, both of which are abolished or reduced by sialidase pretreatment of the corresponding host sialoglycoconjugate receptors. The sialic acid-binding adhesin on Streptococcus gordonii, an early colonizer on the tooth surface, has been molecularly analyzed. The adhesin, Hsa (203-kDa protein), consists of an N-terminal non repetitive region (NR1) including a signal sequence, a relatively short serine-rich region (SR1), a second non repetitive region (NR2), a long serine-rich region (SR2) containing 113 dodecapeptide repeats accounting for 75% of the whole protein, and a C-terminal cell wall anchoring domain. Therefore, it has been suggested that NR2, the putative sialic acid-binding domain of Hsa, is presented on the bacterial surface at the end of a long molecular stalk formed by SR2. The present review deals with the function and pathogenicity of oral streptococcal adhesins.
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PMID:[Adhesins of oral streptococci]. 2372 7