title: Characterization of surface layer proteins from different Clostridium difficile clinical isolates.
abstract: In a previous study we suggested that two surface proteins of a Clostridium difficile strain were involved in the formation of a regularly assembled surface layer (S-layer) external to the cell wall. In the present paper six C. difficile strains isolated from cases and healthy carriers were studied. By using freeze-etching and negative staining techniques two superimposed structurally different lattices were detected on the cell surface of the different C. difficile strains. In each strain, the outer S-layer lattice was arranged in a square symmetry and the inner S-layer lattice in hexagonal symmetry. The S-layer proteins from the different strains were isolated and characterized. Each strain showed two distinct S-layer glycoproteins ranging in molecular mass 36-56 kDa. Antigenic cross-reactivity among the S-layer proteins of higher molecular masses extracted from each strain was demonstrated whereas no antigenic relationship was observed among the different S-layer proteins of lower molecular masses. N-terminal sequence analysis showed the presence of common structural motifs conserved among the high S-layer proteins as well as among the low S-layer proteins. These data indicate that the presence of S-layer on C. difficile strains is common and that its glycoprotein subunits show a certain degree of heterogeneity.
authors.affiliation: Department of Bacteriology and Medical Mycology, Istituto Superiore di Sanità, viale Regina Elena 299, Rome, 00161, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Cerquetti
authors.forename: A
authors.initials: A
authors.lastname: Molinari
authors.forename: A
authors.initials: A
authors.lastname: Sebastianelli
authors.forename: M
authors.initials: M
authors.lastname: Diociaiuti
authors.forename: R
authors.initials: R
authors.lastname: Petruzzelli
authors.forename: C
authors.initials: C
authors.lastname: Capo
authors.forename: P
authors.initials: P
authors.lastname: Mastrantonio
mesh_terms: D000328:Adult; D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000032:analysis* / Q000737:chemistry / Q000648:ultrastructure; D015153:Blotting, Western; D002473:Cell Wall / Q000737:chemistry / Q000187:drug effects / Q000648:ultrastructure; D002648:Child; D016360:Clostridioides difficile / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure; D004591:Electrophoresis, Polyacrylamide Gel; D004761:Enterocolitis, Pseudomembranous / Q000382:microbiology; D005613:Freeze Etching; D006023:Glycoproteins / Q000032:analysis*; D006801:Humans; D007106:Immune Sera; D007231:Infant, Newborn; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D014508:Urea
chemical_list: D001425:Bacterial Outer Membrane Proteins; D006023:Glycoproteins; D007106:Immune Sera; D014508:Urea