Superficial cell-wall layers on Spirillum "Ordal" and their in vitro reassembly.
The cell envelope of Sporillum sp. strain "Ordal" (possibly a variety of S. anulus) demonstrated multiple superficial wall layers which were diverse in their macromolecular arrays. Negative staining and freeze-etching techniques revealed an outer hexagonally packed layer and an inner tetragonally packed layer. However, both thin sections and freeze-etched cleavages of the wall showed that each of these regular structures rested upon a backing layer, and that there was a delicate amorphous layer overlying the outer hexagonal array. Rotary integration, optical deffraction, and reconstruction of image were used to clarify measurements of each array and to verify the validity of a diagrammatic model of the outer hexagonal system. The integrity of these layers required suitable cations (Ca2+ appeared essential) and pH (pH less than or equal to 4.6 dissociated most superficial layers). These observations aided in the development of a low-pH cationic-substitution technique, in which Na+ replaced essential Ca2+, for extraction of the layers from the cell surface. Dialysis to remove Na+ and restoration of Ca2+ initiated in vitro reassembly of the superficial layer components until regularly structured assembly products were formed.
D002118:Calcium; D002473:Cell Wall / Q000648:ultrastructure; D005613:Freeze Etching; D006863:Hydrogen-Ion Concentration; D008961:Models, Structural; D012964:Sodium; D013139:Spirillum / Q000254:growth & development / Q000648:ultrastructure*
D012964:Sodium; D002118:Calcium