Cell-wall composition and viomycin resistance in Rhizobium meliloti

1972 ◽  
Vol 18 (7) ◽  
pp. 1168-1170 ◽  
Author(s):  
C. R. MacKenzie ◽  
D. C. Jordan

Mutation to viomycin-resistance in Rhizobium meliloti R21 resulted in an accumulation of phosphatidylcholine and phosphatidylethanolamine in the cell wall. Resistance to viomycin decreased when the excess lipid was removed by EDTA or when its synthesis was prevented by growth of normally resistant cells at 40 °C. Microelectrophoretic data showed binding of viomycin to the cell surface and it is proposed that the mechanism of resistance to viomycin is an immobilization of the antibiotic in the surface layers of the cell as a result of combination with phospholipid.

Author(s):  
D. James Morré ◽  
Charles E. Bracker ◽  
William J. VanDerWoude

Calcium ions in the concentration range 5-100 mM inhibit auxin-induced cell elongation and wall extensibility of plant stems. Inhibition of wall extensibility requires that the tissue be living; growth inhibition cannot be explained on the basis of cross-linking of carboxyl groups of cell wall uronides by calcium ions. In this study, ultrastructural evidence was sought for an interaction of calcium ions with some component other than the wall at the cell surface of soybean (Glycine max (L.) Merr.) hypocotyls.


Author(s):  
Mary Beth Downs ◽  
Wilson Ribot ◽  
Joseph W. Farchaus

Many bacteria possess surface layers (S-layers) that consist of a two-dimensional protein lattice external to the cell envelope. These S-layer arrays are usually composed of a single species of protein or glycoprotein and are not covalently linked to the underlying cell wall. When removed from the cell, S-layer proteins often reassemble into a lattice identical to that found on the cell, even without supporting cell wall fragments. S-layers exist at the interface between the cell and its environment and probably serve as molecular sieves that exclude destructive macromolecules while allowing passage of small nutrients and secreted proteins. Some S-layers are refractory to ingestion by macrophages and, generally, bacteria are more virulent when S-layers are present.When grown in rich medium under aerobic conditions, B. anthracis strain Delta Sterne-1 secretes large amounts of a proteinaceous extractable antigen 1 (EA1) into the growth medium. Immunocytochemistry with rabbit polyclonal anti-EAl antibody made against the secreted protein and gold-conjugated goat anti-rabbit IgG showed that EAI was localized at the cell surface (fig 1), which suggests its role as an S-layer protein.


2007 ◽  
Vol 98 (16) ◽  
pp. 2985-2992 ◽  
Author(s):  
Gautam Sarath ◽  
Lisa M. Baird ◽  
Kenneth P. Vogel ◽  
Robert B. Mitchell

Author(s):  
Eliza Louback ◽  
Diego Silva Batista ◽  
Tiago Augusto Rodrigues Pereira ◽  
Talita Cristina Mamedes-Rodrigues ◽  
Tatiane Dulcineia Silva ◽  
...  

2015 ◽  
Vol 8 (3) ◽  
pp. 1352-1361 ◽  
Author(s):  
Aaron J. Sindelar ◽  
Craig C. Sheaffer ◽  
John A. Lamb ◽  
Hans-Joachim G. Jung ◽  
Carl J. Rosen

2006 ◽  
Vol 38 (3-5) ◽  
pp. 180-190 ◽  
Author(s):  
Renato Bochicchio ◽  
Carmen L.O. Petkowicz ◽  
Iedo Alquini ◽  
Ana P. Busato ◽  
Fany Reicher

2000 ◽  
Vol 182 (5) ◽  
pp. 1304-1312 ◽  
Author(s):  
Angeles Zorreguieta ◽  
Christine Finnie ◽  
J. Allan Downie

ABSTRACT Rhizobium leguminosarum secretes two extracellular glycanases, PlyA and PlyB, that can degrade exopolysaccharide (EPS) and carboxymethyl cellulose (CMC), which is used as a model substrate of plant cell wall cellulose polymers. When grown on agar medium, CMC degradation occurred only directly below colonies of R. leguminosarum, suggesting that the enzymes remain attached to the bacteria. Unexpectedly, when a PlyA-PlyB-secreting colony was grown in close proximity to mutants unable to produce or secrete PlyA and PlyB, CMC degradation occurred below that part of the mutant colonies closest to the wild type. There was no CMC degradation in the region between the colonies. By growing PlyB-secreting colonies on a lawn of CMC-nondegrading mutants, we could observe a halo of CMC degradation around the colony. Using various mutant strains, we demonstrate that PlyB diffuses beyond the edge of the colony but does not degrade CMC unless it is in contact with the appropriate colony surface. PlyA appears to remain attached to the cells since no such diffusion of PlyA activity was observed. EPS defective mutants could secrete both PlyA and PlyB, but these enzymes were inactive unless they came into contact with an EPS+ strain, indicating that EPS is required for activation of PlyA and PlyB. However, we were unable to activate CMC degradation with a crude EPS fraction, indicating that activation of CMC degradation may require an intermediate in EPS biosynthesis. Transfer of PlyB to Agrobacterium tumefaciens enabled it to degrade CMC, but this was only observed if it was grown on a lawn ofR. leguminosarum. This indicates that the surface ofA. tumefaciens is inappropriate to activate CMC degradation by PlyB. Analysis of CMC degradation by other rhizobia suggests that activation of secreted glycanases by surface components may occur in other species.


2009 ◽  
Vol 114 (3) ◽  
pp. 1042-1049 ◽  
Author(s):  
Catherine M.G.C. Renard ◽  
C. Ginies

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