title: Extracellular polysaccharides associated with thin aggregative fimbriae of Salmonella enterica serovar enteritidis.
abstract: Lipopolysaccharide (LPS) O polysaccharide was identified as the principle factor impeding intercellular formation of intact thin aggregative fimbriae (Tafi) in Salmonella enterica serovar Enteritidis. The extracellular nucleation-precipitation assembly pathway for these organelles was investigated by quantifying fimbrial formation between deltaagfA (AgfA recipient) and deltaagfB (AgfA donor) cells harboring mutations in LPS (galE::Tn10) and/or cellulose (deltabcsA) synthesis. Intercellular complementation could be detected between deltaagfA and deltaagfB strains only when both possessed the galE mutation. LPS O polysaccharide appears to be an impenetrable barrier to AgfA assembly between cells but not within individual cells. The presence of cellulose did not restrict Tafi formation between cells. Transmission electron microscopy of w+ S. enterica serovar Enteritidis 3b cells revealed diffuse Tafi networks without discernible fine structure. In the absence of cellulose, however, individual Tafi fibers were clearly visible, appeared to be occasionally branched, and showed the generally distinctive appearance described for Escherichia coli K-12 curli. A third extracellular matrix component closely associated with cellulose and Tafi was detected on Western blots by using immune serum raised to whole, purified Tafi aggregates. Cellulose was required to tightly link this material to cells. Antigenically similar material was also detected in S. enterica serovar Typhimurium and one diarrheagenic E. coli isolate. Preliminary analysis indicated that this material represented an anionic, extracellular polysaccharide that was distinct from colanic acid. Therefore, Tafi in their native state appear to exist as a complex with cellulose and at least one other component.
authors.affiliation: Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada.
authors.forename: A P
authors.initials: AP
authors.lastname: White
authors.forename: D L
authors.initials: DL
authors.lastname: Gibson
authors.forename: S K
authors.initials: SK
authors.lastname: Collinson
authors.forename: P A
authors.initials: PA
authors.lastname: Banser
authors.forename: W W
authors.initials: WW
authors.lastname: Kay
mesh_terms: D029681:Arabidopsis Proteins; D002482:Cellulose / Q000378:metabolism; D004926:Escherichia coli / Q000502:physiology; D005109:Extracellular Matrix / Q000378:metabolism; D036781:Fimbriae Proteins / Q000235:genetics / Q000378:metabolism; D010861:Fimbriae, Bacterial / Q000502:physiology* / Q000648:ultrastructure; D005816:Genetic Complementation Test; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism; D008854:Microscopy, Electron; D008970:Molecular Weight; D009154:Mutation; D019081:O Antigens / Q000235:genetics / Q000378:metabolism; D011135:Polysaccharides, Bacterial / Q000737:chemistry / Q000378:metabolism*; D012477:Salmonella enteritidis / Q000276:immunology / Q000502:physiology*; D012485:Salmonella typhi / Q000502:physiology; D014534:UDPglucose 4-Epimerase / Q000235:genetics / Q000378:metabolism
chemical_list: C107306:AgfA protein, Salmonella enterica; C435943:AgfB protein, Salmonella; D029681:Arabidopsis Proteins; D019081:O Antigens; D011135:Polysaccharides, Bacterial; D036781:Fimbriae Proteins; D002482:Cellulose; D005964:Glucosyltransferases; C457769:PRC1 protein, Arabidopsis; C028634:cellulose synthase (UDP-forming); D014534:UDPglucose 4-Epimerase; C020551:galactose epimerase