Synthesis and turnover of the regularly arranged surface protein of Acinetobacter sp. relative to the other components of the cell envelope

Methanococcus vannielii is a strictly anaerobic motile coccus that possesses a tuft of flagellae. The cells are markedly sensitive to mechanical stress and are readily lysed by detergents, but the organism grows normally in media of low ionic strength. The absence of a typical cell wall, further suggested by resistance of M. vannielii to penicillin, cycloserine, and vancomycin, was confirmed by ultrastructural studies. Electron micrographs showed that the cell envelope lacks a peptidoglycan layer. On the outer surface there is a regular array of subunits similar to those of the glycoprotein envelopes of the halobacteria. However, the M. vannielii cell envelope, unlike those of the holobacteria, is unable to maintain a definite shape, and a high salt concentration is not required for its integrity.

Section: Resultsmentioning

confidence: 99%

Methanococcus vannielii: ultrastructure and sensitivity to detergents and antibiotics

Jones¹,

Bowers²,

Stadtman³

1977

“…4C). A similar shedding of a surface layer (S-layer) has been seen in other bacteria, such as Acinetobacter sp., S. metamorphum, C. thermohydrosulfuricum, and C. thermosaccharolyticum (1,15,17). The shedding in those bacteria seems to occur as a result of excess synthesis of S-layer subunits, and the amount of material shed into the medium seems to be small.…”

Section: Discussionmentioning

confidence: 99%

Morphological alterations of cell wall concomitant with protein release in a protein-producing bacterium, Bacillus brevis 47

Yamada¹,

Tsukagoshi²,

Udaka³

1981

Bacillus brevis 47 secreted vast amounts of protein into the medium and had a characteristic three-layered cell wall. The three layers are designated, from the outermost to the innermost layer, as the outer wall (4.2 nm), the middle wall(8.5 nm), and the inner wall (2.1-3.7 nm). The inner wall might be a peptidoglycan layer. The fine cell wall structure was morphologically altered to various extents, depending on the growth period. At the early stationary phase of growth, cells began to shed the outer two layers of a limited area of the surface. This shedding was complete after further cell growth. The morphological alterations in the cell wall occurred concomitantly with a prominent increase in protein excretion. When protein secretion was severely inhibited by growing cells with Mg2+, morphological alterations in the cell wall were not observed, even at the late stationary phase of growth. This was also the case with a nonprotein-producing mutant, strain 47-5-25. When cells were incubated in buffers, the outer two layers of the cell wall were specifically removed, leaving cells surrounded only by the inner wall layer. The layers removed by incubation were recovered by high-speed centrifugation. This fraction consisted of two layers resembling the outer and middle wall layers. Protein secreted by B. brevis 47-5 consisted mainly of two proteins with approximate molecular weights of 150,000 and 130,000. Proteins released by incubating cells in buffers and proteins in the outer- and middle-wall-enriched fraction were also composed mainly of two proteins with the same molecular weights as those secreted into the medium. Therefore, we conclude that B. brevis 47 secretes proteins derived from the outer two layers of cell wall and these components are synthesized even after the shedding of the outer two layers.

“…A reciprocal structural dependency between proteins and LPS of the outer membrane has been suggested (2,13,21). Thus, a defect could produce an outer membrane containing either a much lower amount of LPS or a normal amount of LPS that is arranged spatially in an abnormal manner due to the absence of supporting protein molecules.…”

Section: Discussionmentioning

confidence: 99%

Inhibitory action of a non-metabolizable fatty acid on the growth of Escherichia coli: role of metabolism and outer membrane integrity

Fay¹,

Farı́as²

1977

The inhibitory action of decanoic acid on both Escherichia coli K-12/154 (normal lipopolysaccharide) and E. coli RC59 (defective lipopolysaccharide) was studied. A correlation was found between the doubling time of E. coli 154 growing in different media and the lethal effect of 0.4% decanoic acid on this bacterium. Decanoic acid (0.4%) exerted a lytic action on glucose-starved and NaN 1-inhibited cells of E. coli 154 and RC59. Exponentially growing cultures of both strains were not affected by the addition of 0.4% methyldecanoate, but cells of E. coli RC59 reaching the stationary phase were attacked by that compound. A bactericidal action of 0.4% methyldecanoate on exponential E. coli 154 and RC59 was observed when sodium azide was also present in the media. Concentrations lower than 0.01% methyldecanoate had a lytic effect on spheroplasts from E. coli 154 and RC59. These results indicate that the inhibitory action of a non-metabolizable fatty acid on E. coli depends on the cellular metabolic activity and the outer membrane integrity. We previously reported that the extent of growth inhibition by fatty acids in Escherichia coli K-12 and other E. coli strains was dependent on many variables, including the chain length and fatty acid concentration, as well as the growth phase and culture medium in which the bacteria were grown (8). These latter facts suggest that in addition to the mechanisms of