Correlation between molecular size of the surface array protein and morphology and antigenicity of the Campylobacter fetus S layer

Abstract

The correlation between the molecular size of the surface layer protein (S protein) and both structure and antigenicity of the Campylobacter fetus surface layer (S layer) was investigated in several clinical strains and their spontaneous variants which produce S proteins of molecular weights (MW) different from those of the parents. Only three molecular sizes of the S proteins were observed (98, 127, and 149 kDa) in the parental and variant strains. Immunologically, the 98-kDa protein and the 149-kDa protein but not the 127-kDa protein were cross-reactive. Freeze-etching analysis showed that the 98-kDa S protein formed a hexagonal arrangement with a 24-nm center-to-center space and that the S proteins with larger MW (127 or 149 kDa) formed tetragonal ones with an 8-nm center-to-center space. Thus, the MW changes of the S proteins seen in the variant strains were associated with both morphological and antigenic changes in S layer. These observations support the hypothesis that the pattern and antigenicity of the C. fetus S layer is determined by the particular type of S protein. Furthermore, the presence of the two different S layer patterns on a single bacterial cell indicates that multiple S proteins can be produced and expressed in a single cell.

The S‐layer protein of Corynebacterium glutamicum is anchored to the cell wall by its C‐terminal hydrophobic domain

“…In Archaebacteria, they determine and maintain cell shape (Mescher and Strominger, 1976;Wildhaber and Baumeister, 1987). In some cases, S-layers were also identified as virulence factors (Evenberg and Lugtenberg, 1982;Fujimoto et al, 1991;Wang et al, 1993). The structure, composition and chemistry of S-layer proteins have been very well documented.…”

Molecular mechanisms of Campylobacter fetus surface layer protein expression

“…Studies more than 20 years ago of experimentally infected cattle showed that the superficial antigens of sequential C. fetus isolates were changing, but the basis for this phenomenon was not explained (Schurig et al, 1973;Corbeil et al, 1975). More recent in vitro analyses, and studies of experimentally infected animals indicated that it is the SLPs that undergo both antigenic and size variation (Fujimoto et al, 1991;Garcia et al, 1995;Wang et al, 1993). Thus, maintenance of an S-layer has at least two important advantages for C. fetus.…”

“…During in vitro culture, S-layer expression may be lost spontaneously Blaser et al, 1987). As shown with freeze-etched microscopy, these proteins assemble into either hexagonal (97 kDa) or tetragonal (127 and 149 kDa) arrays (Fujimoto et al, 1991) that are non-covalently attached to the cell surface. Like SLPs of Azotobacter, for example, these can be extracted from the bacterial cell with distilled water.…”

“…Serially in vitro passaged C. fetus cells vary both the size of the expressed SLP and its antigenicity (Dubreuil et al, 1990;Fujimoto et al, 1991). Similarly, the SLPs of C. fetus ssp.…”

The Structure and Characterization of the Surface Protein Layer of a Comamonas‐Like Organism

“…Most S-layers are cornposed of a protein subunit with a molecular mass about 40 to 200 kDa which is attached to the underlying cell wall components and arranged in either p2, p4, or p6 symmetry (12). This layer is assumed to act as a barrier between the cell and the environment or as a protector against predators comprising other species of bacteria (2,9,11,13,15).…”