Streptococcus salivarius fimbriae are composed of a glycoprotein containing a repeated motif assembled into a filamentous nondissociable structure

Citation
C. Levesque et al., Streptococcus salivarius fimbriae are composed of a glycoprotein containing a repeated motif assembled into a filamentous nondissociable structure, J BACT, 183(9), 2001, pp. 2724-2732
Citations number
55
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Microbiology
Journal title
JOURNAL OF BACTERIOLOGY
ISSN journal
0021-9193 → ACNP
Volume
183
Issue
9
Year of publication
2001
Pages
2724 - 2732
Database
ISI
SICI code
0021-9193(200105)183:9<2724:SSFACO>2.0.ZU;2-0
Abstract
Streptococcus salivarius, a gram-positive bacterium found in the human oral cavity, expresses flexible peritrichous fimbriae, In this paper, we report purification and partial characterization of S. salivarius fimbriae, Fimbr iae were extracted by shearing the cell surface of hyperfimbriated mutant A 37 (a spontaneous mutant of S. salivarius ATCC 25975) with glass beads. Pre liminary experiments showed that S. salivarius fimbriae did not dissociate when they were incubated at 100 degreesC in the presence of sodium dodecyl sulfate. This characteristic was used to separate them from other cell surf ace components by successive gel filtration chromatography procedures. Fimb riae with molecular masses ranging from 20 x 10(6) to 40 x 10(6) Da were pu rified. Examination of purified fimbriae by electron microscopy revealed th e presence of filamentous structures up to 1 mum long and 3 to 4 nm in diam eter. Biochemical studies of purified fimbriae and an amino acid sequence a nalysis of a fimbrial internal peptide revealed that S. salivarius fimbriae were composed of a glycoprotein assembled into a filamentous structure res istant to dissociation. The internal amino acid sequence was composed of a repeated motif of two amino acids alternating with two modified residues: A /X/T-E-Q-M/phi, where X represents a modified amino acid residue and phi re presents a blank cycle. Immunolocalization experiments also revealed that t he fimbriae were associated with a wheat germ agglutinin-reactive carbohydr ate. Immunolabeling experiments with antifimbria polyclonal antibodies show ed that antigenically related fimbria-like structures were expressed in two other human oral streptococcal species, Streptococcus mitis and Streptococ cus constellatus.