This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Buckmire, F L Articles by Murray, R G Search for Related Content PubMed PubMed Citation Articles by Buckmire, F L Articles by Murray, R G

 Previous Article  |  Next Article 

J Bacteriol. 1976 January; 125(1): 290-299

Substructure and in vitro assembly of the outer, structured layer of Spirillum serpens.

ABSTRACT

Electron micrographs of disintegrating units of the outer, structured (HP) layer of Spirillum serpens and of the isolated protein obtained from the HP layer revealed V- and Y-shaped and linear profiles. Interpretation of these forms, influenced by the seemingly trimeric form of the isolated protein and by biochemical data, suggested that the protein subunits were identical and Y shaped. A model is proposed for the assembly of the Y-shaped subunits to form a hexagon composed of two triads (three Y-shaped subunits each). The isolated protein adsorbed to a template of wall fragments (basal layer) to the same degree (over 90%) in high concentrations of Na+, K+ (5 X 10(-2) M), Ca2+, Sr2+, and Mg2+ (10(-2) M). At a lower concentration (4 x 10(-5) M) of the cations there was differential adsorption of the protein. Adsorption to the template in the presence of each cation, followed by dilution, also led to differential release of the protein. The adsorption of the protein to the basal layer was correlated with reassembly of the HP layer on the template. The mechanisms seem to be: (i) an ionic strength-dependent reassembly, which results in an HP layer loosely attached to the template (this layer is easily dissociated by decreasing the ionic strength); and (ii) a cation-specific (Ca2+ or Sr2+, but not Mg2+, Na+, or K+) mechanism independent of ionic strength. In this latter case, the specific cations presumably form strong noncovalent "salt" linkages between triads and the basal layer, enabling stable hexagons and the HP layer to be formed.