The function of fimbriae in Myxococcus xanthus. II. The role of fimbriae in cell–cell interactions

Abstract

Anti-fimbriae antiserum specifically inhibited swarming but no gliding motility per se in Myxococcus xanthus. However, formation of motile aggregates on agar and clumps in liquid media correlated with the presence of fimbriae. Ethylenediaminetetraacetic acid which inhibited swarming also inhibited fimbriae formation. Direct electron-microscopic observations revealed that fimbriae establish contact with apposing cell surfaces. Intact but not depolymerized fimbriae exhibited hemagglutination activity against guinea pig erythrocytes. This activity was inhibited by mannose, N-acetyl-D-galactosamine, and to a lesser degree by fructose, raffinose, melibiose, and alpha-methyl-D-mannoside. It is concluded that fimbriae are organelles which function to establish and maintain intercellular contacts, perhaps by a lectin-like function, during the coordinated movement of cell aggregates' (swarming) in myxobacteria. This hypothesis is supported by the observations of other workers that genes determining movement of cells in groups also control fimbriation in M. xanthus.

Myxobacteria Produce Outer Membrane-Enclosed Tubes in Unstructured Environments

“…1B), suggesting that fibrils may partly mask or block OMT production. In even earlier studies in the Shimkets and McCurdy labs, it was found that wild-type M. xanthus isolates produce polar structures that look identical to those reported here (13,15,33). Based on their TEM observations, McCurdy and colleagues called the structures polar LPS extrusions, although no direct evidence was provided that they consist of LPS.…”

Mechanism of attachment of swarm cells of Thiothrix nivea

“…In a follow-up study (3), they concluded that fimbriae are organelles which function to establish and maintain intercellular contacts The communal swarming behavior of myxobacteria requires the presence of fimbriae (3,4).…”

Isolation of a surface glycoprotein from Myxococcus xanthus

“…McCurdy and his co-workers (6,7) reported that the fimbriae of M. xanthus were glycoprotein. However, the molecular weight of its subunits, -8,000, and its carbohydrate content, 0.8% (6), clearly distinguish the fimbrial proteins from VGP.…”

“…However, the molecular weight of its subunits, -8,000, and its carbohydrate content, 0.8% (6), clearly distinguish the fimbrial proteins from VGP. It is interesting that fimbriae were required for social but not adventurous motility (7,17) and may play a role in cell-cell interaction. That the carbohydrate portion may participate in this role is suggested by the fact that the hemagglutinating activity displayed by the protein can be inhibited by mannose and N-acetylgalactosamine (7).…”