Minicell formation in chloramphenicol-treated Bacillus cereus

1974 ◽  
Vol 20 (11) ◽  
pp. 1621-1623 ◽  
Author(s):  
K. L. Chung ◽  
L. P. Lin
Keyword(s):  
Cell Wall ◽  
Bacillus Cereus ◽  
Cell Separation ◽  
Synthetic Medium ◽  
Peripheral Cell ◽  
Cell Rupture ◽  
Cytological Changes

Bacillus cereus incubated in a synthetic medium containing chloramphenicol, 19 μg/ml, a concentration which is slightly below the minimal inhibitory level, was observed to form from one to several minicells through a series of cytological changes including septum initiation, invagination and completion at the subpolar region of the cell, rupture of the peripheral cell wall along the circumferential path of this region, and finally cell separation. The minicells are spherical or spheroidal in shape. A small number of heart-shaped cells was also seen.

Thickened cell walls of Bacillus cereus grown in the presence of chloramphenicol: their fate during cell growth

1971 ◽  
Vol 17 (12) ◽  
pp. 1561-1565 ◽  
Author(s):  
K. L. Chung
Keyword(s):  
Cell Wall ◽  
Cell Growth ◽  
Bacillus Cereus ◽  
Cell Walls ◽  
Structural Changes ◽  
Synthetic Medium ◽  
Wall Material ◽  
Partial Removal ◽  
Daughter Cells ◽  
Thickened Wall

Bacillus cereus incubated for 4 h in a synthetic medium containing chloramphenicol was observed to form cell walls 2 to 3 times as thick as those from control cells growing in the same medium containing no antibiotic. Then the cells were washed and reincubated in fresh synthetic medium and the ultra-structural changes in the thickened walls during cell growth and elongation were examined by electron microscopy. After incubation for 20 min, multiple ruptured sites and internal fractures appeared randomly on the surface of the thickened cell wall. Large and small pieces of thickened wall fragments soon "peeled off" from the surface, leaving behind a deeper layer of wall material. Normal cell growth and elongation resumed after partial removal of the thickened cell wall. After several generations, thickened wall fragments were not observed on the surface of daughter cells.

scholarly journals Identification and Characterization of a Peptidoglycan Hydrolase, MurA, of Listeria monocytogenes, a Muramidase Needed for Cell Separation

2003 ◽  
Vol 185 (23) ◽  
pp. 6801-6808 ◽  
Author(s):  
Shannon A. Carroll ◽  
Torsten Hain ◽  
Ulrike Technow ◽  
Ayub Darji ◽  
Philippos Pashalidis ◽  
...  
Keyword(s):  
Cell Wall ◽  
Listeria Monocytogenes ◽  
Cell Separation ◽  
Bacterial Species ◽  
Surface Protein ◽  
Wild Type ◽  
Terminal Domain ◽  
Cell Wall Hydrolase ◽  
Characteristic Features ◽  
Type Gene

ABSTRACT A novel cell wall hydrolase encoded by the murA gene of Listeria monocytogenes is reported here. Mature MurA is a 66-kDa cell surface protein that is recognized by the well-characterized L. monocytogenes-specific monoclonal antibody EM-7G1. MurA displays two characteristic features: (i) an N-terminal domain with homology to muramidases from several gram-positive bacterial species and (ii) four copies of a cell wall-anchoring LysM repeat motif present within its C-terminal domain. Purified recombinant MurA produced in Escherichia coli was confirmed to be an authentic cell wall hydrolase with lytic properties toward cell wall preparations of Micrococcus lysodeikticus. An isogenic mutant with a deletion of murA that lacked the 66-kDa cell wall hydrolase grew as long chains during exponential growth. Complementation of the mutant strain by chromosomal reintegration of the wild-type gene restored expression of this murein hydrolase activity and cell separation levels to those of the wild-type strain. Studies reported herein suggest that the MurA protein is involved in generalized autolysis of L. monocytogenes.

Biochemical characterization of a cortexless mutant of a variant of Bacillus cereus

1976 ◽  
Vol 22 (7) ◽  
pp. 1007-1012 ◽  
Author(s):  
Susanne M. Pearce
Keyword(s):  
Cell Wall ◽  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Bacillus Cereus ◽  
Biochemical Characterization ◽  
Diaminopimelic Acid ◽  
Peptidoglycan Synthesis ◽  
Biochemical Lesion ◽  
Do So

Previous studies on this cortexless mutant of Bacillus cereus var. alesti indicated that the forespore membrane was the site of the biochemical lesion. This hypothesis is supported by the results presented here: fatty acid composition of sporulating cells of the mutant is altered, while in vegetative cells it is comparable to the parent; soluble precursors of peptidoglycan synthesis are accumulated in the mutant, at the time of cortex formation; homogenates of the mutant prepared at the time of cortex formation are unable to incorporate tritiated diaminopimelic acid into peptidoglycan, while homogenates of cells forming germ cell wall do so to an extent comparable to that of the parent; lipid-linked intermediates are formed by the mutant as in the parent. Apparently the mutant is unable either to transfer disaccharide penta-peptide units from the carrier lipid to the growing peptidoglycan acceptor, or to transport lipid-linked intermediates across the forespore membrane.

scholarly journals Mpt5p, a Stress Tolerance- and Lifespan-Promoting PUF Protein in Saccharomyces cerevisiae, Acts Upstream of the Cell Wall Integrity Pathway

2006 ◽  
Vol 6 (2) ◽  
pp. 262-270 ◽  
Author(s):  
Mark S. Stewart ◽  
Sue Ann Krause ◽  
Josephine McGhie ◽  
Joseph V. Gray
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Wall ◽  
Life Span ◽  
Stress Tolerance ◽  
Synthetic Medium ◽  
Cell Wall Integrity ◽  
Puf Proteins ◽  
Downstream Target ◽  
Cell Wall Integrity Pathway ◽  
Puf Protein

ABSTRACT Pumilio family (PUF) proteins affect specific genes by binding to, and inhibiting the translation or stability of, their transcripts. The PUF domain is required and sufficient for this function. One Saccharomyces cerevisiae PUF protein, Mpt5p (also called Puf5p or Uth4p), promotes stress tolerance and replicative life span (the maximum number of doublings a mother cell can undergo before entering into senescence) by an unknown mechanism thought to partly overlap with, but to be independent of, the cell wall integrity (CWI) pathway. Here, we found that mpt5Δ mutants also display a short chronological life span (the time cells stay alive in saturated cultures in synthetic medium), a defect that is suppressed by activation of CWI signaling. We found that Mpt5p is an upstream activator of the CWI pathway: mpt5Δ mutants display the appropriate phenotypes and genetic interactions, display low basal activity of the pathway, and are defective in activation of the pathway upon thermal stress. A set of mRNAs that specifically bind to Mpt5p was recently reported. One such putative target, LRG1, encodes a GTPase-activating protein for Rho1p that directly links Mpt5p to CWI signaling: Lrg1p inhibits CWI signaling, LRG1 mRNA contains a consensus Mpt5p-binding site in its putative 3′ untranslated region, loss of Lrg1p suppresses the temperature sensitivity and CWI signaling defects of mpt5Δ mutants, and LRG1 mRNA abundance is inhibited by Mpt5p. We conclude that Mpt5p is required for normal replicative and chronological life spans and that the CWI pathway is a key and direct downstream target of this PUF protein.

scholarly journals SecDF as Part of the Sec-Translocase Facilitates Efficient Secretion of Bacillus cereus Toxins and Cell Wall-Associated Proteins

PLoS ONE ◽  
2014 ◽  
Vol 9 (8) ◽  
pp. e103326 ◽  
Author(s):  
Aniko Vörös ◽  
Roger Simm ◽  
Leyla Slamti ◽  
Matthew J. McKay ◽  
Ida K. Hegna ◽  
...  
Keyword(s):  
Cell Wall ◽  
Bacillus Cereus ◽  
Associated Proteins

scholarly journals Phylogenetic and comparative functional analysis of the cell-separation α-glucanase Agn1p in Schizosaccharomyces

Microbiology ◽  
2014 ◽  
Vol 160 (6) ◽  
pp. 1063-1074 ◽  
Author(s):  
Matthias Sipiczki ◽  
Anita Balazs ◽  
Aniko Monus ◽  
Laszlo Papp ◽  
Anna Horvath ◽  
...  
Keyword(s):  
Cell Wall ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Mother Cell ◽  
Cell Separation ◽  
Yeast Cells ◽  
Glycoside Hydrolase Family ◽  
Binding Domains ◽  
Yeast Phase ◽  
Mother Cell Wall

The post-cytokinetic separation of cells in cell-walled organisms involves enzymic processes that degrade a specific layer of the division septum and the region of the mother cell wall that edges the septum. In the fission yeast Schizosaccharomyces pombe, the 1,3-α-glucanase Agn1p, originally identified as a mutanase-like glycoside hydrolase family 71 (GH71) enzyme, dissolves the mother cell wall around the septum edge. Our search in the genomes of completely sequenced fungi identified GH71 hydrolases in Basidiomycota, Taphrinomycotina and Pezizomycotina, but not in Saccharomycotina. The most likely Agn1p orthologues in Pezizomycotina species are not mutanases having mutanase-binding domains, but experimentally non-characterized hypothetical proteins that have no carbohydrate-binding domains. The analysis of the GH71 domains corroborated the phylogenetic relationships of the Schizosaccharomyces species determined by previous studies, but suggested a closer relationship to the Basidiomycota proteins than to the Ascomycota proteins. In the Schizosaccharomyces genus, the Agn1p proteins are structurally conserved: their GH71 domains are flanked by N-terminal secretion signals and C-terminal sequences containing the conserved block YNFNAY/HTG. The inactivation of the agn1Sj gene in Schizosaccharomyces japonicus, the only true dimorphic member of the genus, caused a severe cell-separation defect in its yeast phase, but had no effect on the hyphal growth and yeast-to-mycelium transition. It did not affect the mycelium-to-yeast transition either, only delaying the separation of the yeast cells arising from the fragmenting hyphae. The heterologous expression of agn1Sj partially rescued the separation defect of the agn1Δ cells of Schizosaccharomyces pombe. The results presented indicate that the fission yeast Agn1p 1,3-α-glucanases of Schizosaccharomyces japonicus and Schizosaccharomyces pombe share conserved functions in the yeast phase.

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