title: Surface properties from the S-layer of Clostridium thermosaccharolyticum D120-70 and Clostridium thermohydrosulfuricum L111-69.
abstract: Labelling experiments using a positively charged topographical marker for electron microscopy, polycationized ferritin, showed that the S-layers of two closely related clostridia Clostridium thermohydrosulfuricum L111-69 and C. thermosaccharolyticum D120-70 do not exhibit a net negative charge, as usually observed for bacterial cell surfaces. Chemical modification of reactive sites confirmed that amino and carboxyl groups are exposed on the S-layer surface of both strains. Amino-specific, bifunctional agents crosslinked both S-layer lattices. Studies with carbodiimides revealed that only the S-layer surface of C. thermohydrosulfuricum L111-69 had amino and carboxyl groups closely enough aligned to permit electrostatic interactions between the constituent protomers. The regular structure of this S-layer lattice was lost upon converting the carboxyl groups into neutral groups by amidation. Disintegration of both S-layer lattices occurred upon N-acetylation or N-succinylation of the free amino groups. Adhesion experiments showed that in neutral and weakly alkaline environment whole cells of C. thermosaccharolyticum D120-70 exhibited a stronger tendency to bind to charged surfaces than whole cells of C. thermohydrosulfuricum L111-69, but showed a lower tendency to bind to hydrophobic materials.
authors.affiliation: Zentrum für Ultrastrukturforschung, Universität für Bodenkultur, Wien, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Sára
authors.forename: I
authors.initials: I
authors.lastname: Kalsner
authors.forename: U B
authors.initials: UB
authors.lastname: Sleytr
mesh_terms: D002473:Cell Wall / Q000648:ultrastructure; D003013:Clostridium / Q000648:ultrastructure*; D005613:Freeze Etching; D008562:Membrane Glycoproteins / Q000302:isolation & purification*; D008854:Microscopy, Electron; D013045:Species Specificity
chemical_list: D008562:Membrane Glycoproteins