Sporulation-associated Mother Cell Lysis in Bacillus Displays Markers of Programmed Cell Death (original) (raw)
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Apoptosis in bacteria Programmed cell death in prokaryotic cells
Apoptosis is a phenomenon discovered by Professor John F. in which the cell, in response to specific stimuli, begins a suicide process in which the DNA fragments, the chromatin condenses, the cytoskeleton fragments, and the cell breaks up into apoptotic bodies. Though this phenomenon is most thoroughly understood in eukaryotic cells, researchers have discovered a modified form of apoptosis in bacterial cells, in which the cell autolysis, or "selfbursts". The cell does this to perhaps provide nutrition for other cells as it functions as a multicellular colony, or for nutrition of a germinating spore, or for DNA transformation purposes. The markers of this process include DNA fragmentation, chromosome condensation, and phosphotidylserine exposure. This process has genes and proteins that are distinct from those that are present in eukaryotic apoptosis and are still under research at present. Research into this field will allow us to fully understand the cell life cycle of a prokaryotic cell and potentially have important clinical implications for the control of drug-resistant bacterial infections and the development of new antibacterial drugs to combat this clinical issue. This paper will discuss the presence of apoptosis in bacterial cells, as well as the genes involved and the purpose of this action. Clinical applications of bacterial apoptosis will also be analyzed.
Bacterial programmed cell death and multicellular behavior in bacteria
PLoS genetics, 2006
Traditionally, programmed cell death (PCD) is associated with eukaryotic multicellular organisms. However, recently, PCD systems have also been observed in bacteria. Here we review recent research on two kinds of genetic programs that promote bacterial cell death. The first is mediated by mazEF, a toxin-antitoxin module found in the chromosomes of many kinds of bacteria, and mainly studied in Escherichia coli. The second program is found in Bacillus subtilis, in which the skf and sdp operons mediate the death of a subpopulation of sporulating bacterial cells. We relate these two bacterial PCD systems to the ways in which bacterial populations resemble multicellular organisms.
Characterization of a cloned Bacillus subtilis gene that inhibits sporulation in multiple copies
Journal of Bacteriology, 1986
We have isolated a 1.0-kilobase fragment of the Bacillus subtilis chromosome which, when present in high-copy-number plasmids, caused a sporulation-proficient strain to become phenotypically sporulation deficient. This is referred to as the sporulation inhibition (Sin) phenotype. This DNA fragment, in multicopy, also inhibited the production of extracellular protease activity, which normally appears at the beginning of stationary growth. The origin of the fragment was mapped between the dnaE and spoOA genes on the B. subtilis chromosome, and its complete DNA sequence has been determined. By analysis of various deletions and a spontaneous mutant the Sin function was localized to an open reading frame (ORF) predicted from the DNA sequence. Inactivation of this ORF in the chromosome did not affect the ability of cells to sporulate. However, the late-growth-associated production of proteases and alpha-amylase was elevated in these cells. The predicted amino acid sequence of the protein encoded by this ORF had a DNA-binding domain, typically present in several regulatory proteins. We propose that the sin ORF encodes a regulatory protein that is involved in the transition from vegetative growth to sporulation.
Hpr (ScoC) and the phosphorelay couple cell cycle and sporulation in Bacillus subtilis
FEMS Microbiology Letters, 2004
Bacillus subtilis sporulation is a developmental process that culminates in the formation of a highly resistant and persistent endospore. Inhibiting DNA synthesis prior to the completion of the final round of DNA replication blocks sporulation at an early stage. Conditions that prevent compartmentalization of gene expression, i.e. inhibition of asymmetric septum formation or chromosome partitioning, also block sporulation at an early stage. Multiple mechanisms including a RecA-dependent, a RecA-independent, and the soj-spo0J operon have been implicated in signal transduction, connecting DNA replication and chromosome partitioning to the onset of sporulation in B. subtilis. We suggest that a single mechanism involving Hpr (ScoC) and Sda couple cell cycle signaling to sporulation initiation. We show that transcription of phosphorelay sensory chain genes is adversely affected by post-exponential perturbation of the cell cycle. DNA replication arrest by chemical treatments, such as hydroxyphenylazouracil, hydroxyurea, nalidixic acid, and through genetic means using dnaA1 ts and dnaB19 ts temperature-sensitive mutants caused substantial down-regulation of spo0F and kinA expression and elevated the expression of spo0A and spo0H (sigH). Despite the elevation in spo0A expression, Spo0AVP-dependent sinI expression was substantially down-regulated indicating that in vivo Spo0AVP levels may be diminished. Similar alterations in gene expression patterns were observed in an ftsA279 ts mutant background, indicating that cytokinesis and sporulation may also be coupled by a similar mechanism. Loss of function mutation in hpr (scoC) restored sporulation in a dnaA1 ts mutant, blocked the DNA replication arrest induction of spo0A expression and restored expression of spo0F, kinA and sinI. Moreover, hpr expression was up-regulated in response to DNA replication arrest. The increase in hpr expression required Sda. These results suggest a role for Hpr (ScoC) in mediating the coupling of cell cycle events to the onset of sporulation. ß 2004 Published by Elsevier B.V. on behalf of the Federation of European Microbiological Societies.
Journal of Bacteriology, 1997
We used immunofluorescence microscopy to investigate mechanisms governing the establishment of cell-specific gene transcription during sporulation in the bacterium Bacillus subtilis. The transcription factors sigma E and sigma F are synthesized shortly after the start of sporulation but do not become active in directing gene transcription until after polar division, when the activity of sigma E is confined to the mother cell and the activity of sigma F is restricted to the forespore. We show that shortly after septation, sigma E and its proprotein precursor pro-sigma E appear to be absent from the forespore and that a null mutation in spoIIIE, a gene known to be required for the translocation of a chromosome into the forespore, allows sigma E and/or pro-sigma E to persist and sigma E to become active in the forespore. These findings suggest that the loss of sigma E/pro-sigma E from the forespore contributes to the compartmentalization of sigma E-directed gene transcription. We also ...
Identification of Bacillus subtilis genes expressed early during sporulation
Molecular Microbiology, 1989
Labelled cDNA transcribed in vHro from early-sporulatJon RNA was enriched for sporulation-specific sequences by subtractive hybridization to an excess of vegetative RNA and used to probe libraries of Bacillus subtilis chromosomal DNA. From the initial collection of clones that coded for RNAs transcribed preferentially during sporutation, several were subcloned and studied in more detail. It was found that two clones contained sequences (dcIA and dciB) that had an undetectable level of transcription during vegetative growth but had transcripts that started to appear no later than eight minutes after induction of
Properties of purified sporlets produced by spoII mutants of Bacillus subtilis
1992
A number of abortively disporic spoII mutants of Bacillus subtilis released their forespore compartments (termed stage II sporlets) after mother cell lysis during sporulation in nutrient exhaustion or resuspension media. Stage II sporlets were viable and contained levels of ATP and a number of enzymes similar to those in cells 2 to 3 h after sporulation. However, stage II sporlets carried out essentially no macromolecular synthesis, a result suggesting that they were in a quiescent state. The nucleoid of these quiescent stage II sporlets was significantly condensed relative to that in the original vegetative cells, as was previously found to take place 1 to 2 h after initiation of sporulation (B. Setlow, N. Magill, P. Febbroriello, L. Nakhimousky, D. E. Koppel, and P. Setlow, J. Bacteriol. 173:6270-6278, 1991). Stage H sporlets may be a useful model system for analysis of forespore properties early in stage II of sporulation. Members of the gram-positive genera Bacillus and Clostrid...