Intracellular, periodic structures in the gliding bacterium Myxococcus xanthus

Abstract

Electron microscopic observations of thin sections of Myxococcus xanthus vegetative cells revealed the presence of cytoplasmic bundles of 4- to 5-nm-diameter filaments running longtitudinally below the cell membrane and terminating in association with the envelope near one pole. Part of each bundle demonstrated a herringbone-like periodicity (approximately 12-nm spacing). This structure was observed in cells from shake cultures and in gliding cells fixed by several methods. It is proposed that the structure may be attached to the envelope near both poles in gliding cells and that the motive force for motility may be provided by its contraction and relaxation. In one of four nongliding mutants examined, the periodicity was indistinct or lacking. In this mutant another structure, comprised of linearly arrayed beads, was observed in association with the filamentous bundle. Another structure, characterized by major, transverse bands (approximately 34 nm apart), occurred in patches that may traverse the diameter of the wild-type cells in which the structure was observed.

Ultrastructural Details of the Apparatus of Gliding Motility of Myxococcus fulvus (Myxobacterales)

“…The mechanism by which gliding bacteria move on solid surfaces has been under discussion for many years. Many hypotheses exist which are based on different principles such as: directional extrusion of slime (Jahn, 1924;Henrichsen, 1972;Ridgeway & Lewin, 1973); contractile tubular elements in the cytoplasm (Schmidt-Lorenz & Kuhlwein, 1968 ;Schmidt-Lorenz, 1969;Bisalputra et al, 1975;MacRae & McCurdy, 1975, 1976Burchard et al, 1977); contraction waves along the cell surface (Graf, 1965;Pate & Ordal, 1967;Doetsch & Hageage, 1968;Halfen & Castenholz, 1971;Henrichsen, 1972;Halfen, 1973 ; Humphrey rt a/., 1979); polar fimbriation (MacRae & McCurdy, 1976); and excretion of surface-active material (Dworkin et al, 1983;Keller et al, 1983). In addition, at least in myxobacteria, there exists evidence for a considerable genetic complexity of the gliding machinery involving about 40 genes (for a review see Kaiser et al, 1979).…”

Biology and global distribution of myxobacteria in soils

“…In the cells mesosomes and mesosome-like membrane bodies have been found [50], and further di¡erent intracellular granules and inclusion bodies (polyphosphates, polysaccharides). Burchard [51] detected bundles of microtubules and ¢brils in the cytoplasm. This system of contractile ¢brils has hence been considered as responsible for the gliding movement of vegetative cells.…”

“…Several models have been proposed to explain the gliding mechanism. Burchard proposed that it is based upon bundles of ¢laments and tubules that are arranged longitudinally as well as diagonally beneath the cell membrane [51] (see also above Section 2.3). Waves of contraction are supposed to propel the cells [60].…”

Ultrastructural and biochemical changes in a prokaryote induced by cytoskeletal active drugs

“…Recently, actin-like and myosin-like proteins have been isolated from the cytoplasm of E. coli and Mycoplasma [5][6][7][8][9]. While the function of these and possibly other proteins is unclear, they could be involved in a structural function in the cell cytoplasm and nucleus [10][11][12][13][14][15]. Since specific inhibitors of microfilament (cytochalasin B) and microtubule (vinblastin and colchicine) assembly and stabilization in eukaryotes are available [16,17], we have determined their effects on the ultrastructure and on certain biochemical functions in a prokaryote, E. co#.…”