Factors contributing to helical shape determination and maintenance in Bacillus subtilis macrofibres

Mendelson, Neil H.; Thwaites, J. J.; Favre, D.; Surana, Uttam; Briehl, Margaret M.; Wolfe, Alan J.

doi:10.1016/s0769-2609(85)80029-6

Cited by 12 publications

(9 citation statements)

References 4 publications

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“…It is possible that this is true of cell wall properties, but an inordinate amount of time would be required to demonstrate this. A twist in macrofibers also changes (reversibly) when the pH is reduced to 4 or less (19). The lack of measured change in cell wall stiffness due to washing threads of low pH might indicate that twist is not a mechanical response, but these results are for the axial modulus only.…”

Section: Discussionmentioning

confidence: 98%

“…A twist in macrofibers, which is thought to be a mechanical response depending on polymer conformation, changes with exposure to various ions as if they were arranged in a lyotropic series (19). It is possible that this is true of cell wall properties, but an inordinate amount of time would be required to demonstrate this.…”

Section: Discussionmentioning

confidence: 99%

“…This growth medium (TB medium) contains NaCl. Salts and pH also have considerable influence over bacterial macrofiber conformation, not only during growth but also in immediate response to environmental change (16,19). The geometry of macrofibers is thought to be mechanically determined, so that ion-induced changes in wall mechanical properties could be the cause.…”

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confidence: 99%

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Mechanical properties of Bacillus subtilis cell walls: effects of ions and lysozyme

1991

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Bacterial threads of BacUlus subtilis have been immersed in, and redrawn from, water of various pH values, in solutions of (NH4)2SO4 and NaCI of various concentrations, and in Iysozyme solutions. The changes in the tensile strength, elastic modulus, and other mechanical properties of the bacterial cell wall due to these treatments were obtained. The data show that change in pH has little effect but that as the salt concentration is increased, the cell walls become more ductile. A high salt concentration (1 M NaCI) can reduce the modulus by a factor of 26 to 13.5 MPa at 81% relative humidity and the strength by a factor of only 2.5. Despite attacking the septal-wall region of the cellular filaments, Iysozyme has no effect on the mechanical properties. There is no significant change in the stress relaxation behavior due to any of the treatments. The dependence of mechanical properties on the salt concentration is discussed in terms of the polyelectrolyte nature of cell walls. The evidence presented in this and the accompanying paper (J. J. Thwaites and U. C. Surana, J. Bacteriol., 173:197-203, 1991) supports the idea that the peptidoglycan in bacterial cell wall is an entanglement network with a large degree of molecular flexibility, with some order but no regular structure.

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Mechanical properties of Bacillus subtilis cell walls: effects of ions and lysozyme

1991

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“…In previous work we have shown that electrostatic interactions in the cell wall contribute to the maintenance of macrofiber twist (19) and that ions such as magnesium influence the establishment of twist states (18). We suggested that macrofiber twist states reflect structural states of the cell wall (16) (2,3,8,10,13).…”

Section: Discussionmentioning

confidence: 99%

Regulation of Bacillus subtilis macrofiber twist development by ions: effects of magnesium and ammonium

Mendelson¹,

Favre²

1987

J Bacteriol

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The steady-state twist of Bacillus subtilis macrofibers produced by growth in complex medium was found to vary as a function of the magnesium and ammonium concentrations. Four categories of macrofiber-producing strains that differed in their response to temperature regulation of twist were studied. Macrofibers were cultured in the complex medium TB used in previous experiments and in two derivative media, T (consisting of Bacto Tryptose), in which most strains produced left-handed structures, and Be (consisting of Bacto Beef Extract), in which right-handed macrofibers arose. In nearly all cases, increasing concentrations of magnesium led to the production of macrofibers with greater right-handed twist. Some strains unable to form right-handed structures as a function of temperature could be made to do so by the addition of magnesium. Inversion from right-to left-handedness in strain FJ7 induced by temperature shift-up was blocked by the addition of magnesium. The presence of magnesium during a high-temperature pulse did not block the establishment of "memory," although it delayed the initiation of the transient inversion following return to low temperature. The twist state of macrofibers grown without a magnesium supplement was not instantaneously affected by the addition of magnesium. Such fibers were, however, protected from lysozyme attack and associated relaxation motions. Lysozyme degradation of purified cell walls (both intact and lacking teichoic acid) was also blocked by the addition of magnesium. Ammonium ions influenced macrofiber twist development towards the left-hand end of the twist spectrum. Macrofiber twist produced in mixtures of magnesium and ammonium was strain and medium dependent. FJ7 was much more responsive to ammonium than magnesium ions, producing left-handed structures over most of the interaction matrix. In contrast, strain 734 was more responsive to magnesium in medium T, producing right-handed structures over most of the matrix, but in medium Be responded preferentially to ammonium ions and produced left-handed structures over most of the matrix. The results suggest that charge interactions at the time of cell wall assembly influence the conformational states of cell wall polymers and consequently affect the geometry of growth as well as cell shape determination.

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“…Although genetically determined, twist state is profoundly affected by the composition of the growth medium, temperature, specific ions, proteases, lysozyme, and possibly water activity (4,(10)(11)(12). These factors are thought to operate by regulation of cell surface assembly during growth and by control of interactions within the cell wall (13). D-Alanine is predominantly found in two cell surface components, peptidoglycan and teichoic acid.…”

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confidence: 99%

Regulation of Bacillus subtilis macrofiber twist development by D-alanine

1988

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Twist states ofBacillus subtilis macrofibers were found to vary as a function of the concentration of Du-alanine in the medium during growth. L-Alanine in the same concentration range had no effect. Increasing concentrations of D-alanine resulted in structures progressively more right-handed (or less left-handed). All strains examined in this study, including mutants fixed in the left-hand domain as a function of temperature, responded to D-alanine in the same way. All twist states from tight left-to tight right-handedness could be achieved solely by varying the D-alanine concentration. The D-alanine-requiring macrofiber strain 2C8, which carries a genetic defect (dal-l) in the alanine racemase, behaved in a similar fashion. The combined effects of D-alanine and ammonium sulfate (a factor known to influence macrofiber twist development in the leftward direction) were examined by using both strains able to undergo temperature-induced helix hand inversion and others incapable of doing so. In all cases, the effects of D-alanine predominated. A synergism was found in which increasing the concentration of ammonium sulfate in the presence of D-alanine enhanced the right-factor activity of the latter. A D-alanine pulse protocol provided evidence that structures undergo a transient inversion indicative of "memory." Chloramphenicol treatment inhibited the establishment of memory in the D-alanineinduced right to left inversion, supporting the existence of a "left twist protein(s)" that is required for the attainment of left-handed twist states. Chemical analysis of cell walls obtained from right-and left-handed macrofibers produced in the presence and absence of D-alanine, respectively, failed to reveal twist state-specific differences in the overall composition of either peptidoglycan or wall teichoic acids.

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Factors contributing to helical shape determination and maintenance in Bacillus subtilis macrofibres

Cited by 12 publications

References 4 publications

Mechanical properties of Bacillus subtilis cell walls: effects of ions and lysozyme

Mechanical properties of Bacillus subtilis cell walls: effects of ions and lysozyme

Regulation of Bacillus subtilis macrofiber twist development by ions: effects of magnesium and ammonium

Regulation of Bacillus subtilis macrofiber twist development by D-alanine

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