scholarly journals SpoIIB Localizes to Active Sites of Septal Biogenesis and Spatially Regulates Septal Thinning during Engulfment in Bacillus subtilis

2000 ◽  
Vol 182 (4) ◽  
pp. 1096-1108 ◽  
Author(s):  
Ana R. Perez ◽  
Angelica Abanes-De Mello ◽  
Kit Pogliano
Keyword(s):  
Bacillus Subtilis ◽  
Fusion Protein ◽  
Mother Cell ◽  
Active Sites ◽  
Time Lapse ◽  
Formation Pathway ◽  
Time Lapse Microscopy ◽  
Division Site ◽  
Proposal A

ABSTRACT A key step in the Bacillus subtilis spore formation pathway is the engulfment of the forespore by the mother cell, a phagocytosis-like process normally accompanied by the loss of peptidoglycan within the sporulation septum. We have reinvestigated the role of SpoIIB in engulfment by using the fluorescent membrane stain FM 4-64 and deconvolution microscopy. We have found thatspoIIB mutant sporangia display a transient engulfment defect in which the forespore pushes through the septum and bulges into the mother cell, similar to the situation in spoIID,spoIIM, and spoIIP mutants. However, unlike the sporangia of those three mutants, spoIIB mutant sporangia are able to complete engulfment; indeed, by time-lapse microscopy, sporangia with prominent bulges were found to complete engulfment. Electron micrographs showed that in spoIIB mutant sporangia the dissolution of septal peptidoglycan is delayed and spatially unregulated and that the engulfing membranes migrate around the remaining septal peptidoglycan. These results demonstrate that mother cell membranes will move around septal peptidoglycan that has not been completely degraded and suggest that SpoIIB facilitates the rapid and spatially regulated dissolution of septal peptidoglycan. In keeping with this proposal, a SpoIIB-myc fusion protein localized to the sporulation septum during its biogenesis, discriminating between the site of active septal biogenesis and the unused potential division site within the same cell.

scholarly journals Dynamics of the Bacillus subtilis Min system

2020 ◽  
Author(s):  
Helge Feddersen ◽  
Laeschkir Würthner ◽  
Erwin Frey ◽  
Marc Bramkamp
Keyword(s):  
Bacillus Subtilis ◽  
Active Sites ◽  
Dynamic Equilibrium ◽  
Model Organism ◽  
Physical Modelling ◽  
Division Site ◽  
Diffusion Constants ◽  
Dynamic Equilibrium State ◽  
Min Proteins

SummaryDivision site selection is a vital process to ensure generation of viable offspring. In many rod-shaped bacteria a dynamic protein system, termed the Min system, acts as a central regulator of division site placement. The Min system is best studied in Escherichia coli where it shows a remarkable oscillation from pole to pole with a time-averaged density minimum at midcell. Several components of the Min system are conserved in the Gram-positive model organism Bacillus subtilis. However, in B. subtilis it is believed that the system forms a stationary bipolar gradient from the cell poles to midcell. Here, we show that the Min system of B. subtilis localizes dynamically to active sites of division, often organized in clusters. We provide physical modelling using measured diffusion constants that describe the observed enrichment of the Min system at the septum. Modelling suggests that the observed localization pattern of Min proteins corresponds to a dynamic equilibrium state. Our data provide evidence for the importance of ongoing septation for the Min dynamics, consistent with a major role of the Min system to control active division sites, but not cell pole areas.

scholarly journals Use of time-lapse microscopy to visualize rapid movement of the replication origin region of the chromosome during the cell cycle in Bacillus subtilis

1998 ◽  
Vol 28 (5) ◽  
pp. 883-892 ◽  
Author(s):  
Chris D. Webb ◽  
Peter L. Graumann ◽  
Jason A. Kahana ◽  
Aurelio A. Teleman ◽  
Pamela A. Silver ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Bacillus Subtilis ◽  
Replication Origin ◽  
Time Lapse ◽  
Time Lapse Microscopy ◽  
Rapid Movement ◽  
Use Of Time ◽  
Origin Region

scholarly journals Assembly of Multiple CotC Forms into the Bacillus subtilis Spore Coat

2004 ◽  
Vol 186 (4) ◽  
pp. 1129-1135 ◽  
Author(s):  
Rachele Isticato ◽  
Giovanni Esposito ◽  
Rita Zilhão ◽  
Sofia Nolasco ◽  
Giuseppina Cangiano ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Posttranslational Modifications ◽  
Mother Cell ◽  
Spore Coat ◽  
Spore Surface ◽  
Subtilis Spore ◽  
Cell Compartment ◽  
Bacillus Subtilis Spore ◽  
Molecular Masses

ABSTRACT We report evidence that the CotC polypeptide, a previously identified component of the Bacillus subtilis spore coat, is assembled into at least four distinct forms. Two of these, having molecular masses of 12 and 21 kDa, appeared 8 h after the onset of sporulation and were probably assembled on the forming spore immediately after their synthesis, since no accumulation of either of them was detected in the mother cell compartment, where their synthesis occurs. The other two components, 12.5 and 30 kDa, were generated 2 h later and were probably the products of posttranslational modifications of the two early forms occurring directly on the coat surface during spore maturation. None of the CotC forms was found either on the spore coat or in the mother cell compartment of a cotH mutant. This indicates that CotH serves a dual role of stabilizing the early forms of CotC and promoting the assembly of both early and late forms on the spore surface.

scholarly journals Cohesion of Sister Chromosome Termini during the Early Stages of Sporulation in Bacillus subtilis

2020 ◽  
Vol 202 (20) ◽  
Author(s):  
Clare Willis ◽  
Jeff Errington ◽  
Ling Juan Wu
Keyword(s):  
Cell Cycle ◽  
Bacillus Subtilis ◽  
Mother Cell ◽  
Developmental Process ◽  
Time Lapse ◽  
Axial Filament ◽  
Content Type ◽  
Early Stages ◽  
Cell Compartments ◽  
Sister Chromosome

ABSTRACT During sporulation of Bacillus subtilis, the cell cycle is reorganized to generate separated prespore and mother cell compartments, each containing a single fully replicated chromosome. The process begins with reorganization of the nucleoid to form an elongated structure, the axial filament, in which the two chromosome origins are attached to opposite cell poles, with the remainder of the DNA stretched between these sites. When the cell then divides asymmetrically, the division septum closes around the chromosome destined for the smaller prespore, trapping the origin-proximal third of the chromosome in the prespore. A translocation pore is assembled through which a DNA transporter, SpoIIIE/FtsK, transfers the bulk of the chromosome to complete the segregation process. Although the mechanisms involved in attaching origin regions to the cell poles are quite well understood, little is known about other aspects of axial filament morphology. We have studied the behavior of the terminus region of the chromosome during sporulation using time-lapse imaging of wild-type and mutant cells. The results suggest that the elongated structure involves cohesion of the terminus regions of the sister chromosomes and that this cohesion is resolved when the termini reach the asymmetric septum or translocation pore. Possible mechanisms and roles of cohesion and resolution are discussed. IMPORTANCE Endospore formation in Firmicutes bacteria provides one of the most highly resistant life forms on earth. During the early stages of endospore formation, the cell cycle is reorganized so that exactly two fully replicated chromosomes are generated, before the cell divides asymmetrically to generate the prespore and mother cell compartments that are critical for the developmental process. Decades ago, it was discovered that just prior to asymmetrical division the two chromosomes enter an unusual elongated configuration called the axial filament. This paper provides new insights into the nature of the axial filament structure and suggests that cohesion of the normally separated sister chromosome termini plays an important role in axial filament formation.

scholarly journals Contrasting Effects of σE on Compartmentalization of σF Activity during Sporulation of Bacillus subtilis

2004 ◽  
Vol 186 (7) ◽  
pp. 1983-1990 ◽  
Author(s):  
David W. Hilbert ◽  
Vasant K. Chary ◽  
Patrick J. Piggot
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Bacillus Subtilis ◽  
Mother Cell ◽  
Cell Fates ◽  
Gene Encoding ◽  
Primitive Form ◽  
Small Proteins ◽  
Dna Translocase

ABSTRACT Spore formation by Bacillus subtilis is a primitive form of development. In response to nutrient starvation and high cell density, B. subtilis divides asymmetrically, resulting in two cells with different sizes and cell fates. Immediately after division, the transcription factor σF becomes active in the smaller prespore, which is followed by the activation of σE in the larger mother cell. In this report, we examine the role of the mother cell-specific transcription factor σE in maintaining the compartmentalization of gene expression during development. We have studied a strain with a deletion of the spoIIIE gene, encoding a DNA translocase, that exhibits uncompartmentalized σF activity. We have determined that the deletion of spoIIIE alone does not substantially impact compartmentalization, but in the spoIIIE mutant, the expression of putative peptidoglycan hydrolases under the control of σE in the mother cell destroys the integrity of the septum. As a consequence, small proteins can cross the septum, thereby abolishing compartmentalization. In addition, we have found that in a mutant with partially impaired control of σF, the activation of σE in the mother cell is important to prevent the activation of σF in this compartment. Therefore, the activity of σE can either maintain or abolish the compartmentalization of σF, depending upon the genetic makeup of the strain. We conclude that σE activity must be carefully regulated in order to maintain compartmentalization of gene expression during development.

scholarly journals A Dispensable Role for Forespore-Specific Gene Expression in Engulfment of the Forespore during Sporulation ofBacillus subtilis

2000 ◽  
Vol 182 (10) ◽  
pp. 2919-2927 ◽  
Author(s):  
Ya-Lin Sun ◽  
Marc D. Sharp ◽  
Kit Pogliano
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Sigma Factor ◽  
Mother Cell ◽  
Spore Production ◽  
Specific Gene ◽  
Ofbacillus Subtilis ◽  
Formation Pathway ◽  
Specific Gene Expression

ABSTRACT During the stage of engulfment in the Bacillus subtilisspore formation pathway, the larger mother cell engulfs the smaller forespore. We have tested the role of forespore-specific gene expression in engulfment using two separate approaches. First, using an assay that unambiguously detects sporangia that have completed engulfment, we found that a mutant lacking the only forespore-expressed engulfment protein identified thus far, SpoIIQ, is able to efficiently complete engulfment under certain sporulation conditions. However, we have found that the mutant is defective, under all conditions, in the expression of the late-forespore-specific transcription factor ςG; thus, SpoIIQ is essential for spore production. Second, to determine if engulfment could proceed in the absence of forespore-specific gene expression, we made use of a strain in which activation of the mother cell-specific sigma factor ςE was uncoupled from forespore-specific gene expression. Remarkably, engulfment occurred in the complete absence of ςF-directed gene expression under the same conditions permissive for engulfment in the absence of SpoIIQ. Our results demonstrate that forespore-specific gene expression is not essential for engulfment, suggesting that the machinery used to move the membranes around the forespore is within the mother cell.

scholarly journals Opposing actions of septins and Sticky on Anillin promote the transition from contractile to midbody ring

2013 ◽  
Vol 203 (3) ◽  
pp. 487-504 ◽  
Author(s):  
Nour El Amine ◽  
Amel Kechad ◽  
Silvana Jananji ◽  
Gilles R.X. Hickson
Keyword(s):  
Essential Role ◽  
Time Lapse ◽  
Maturation Process ◽  
S2 Cells ◽  
Contractile Ring ◽  
Time Lapse Microscopy ◽  
Drosophila Melanogaster S2 Cells ◽  
C Terminus ◽  
N Terminus

During cytokinesis, closure of the actomyosin contractile ring (CR) is coupled to the formation of a midbody ring (MR), through poorly understood mechanisms. Using time-lapse microscopy of Drosophila melanogaster S2 cells, we show that the transition from the CR to the MR proceeds via a previously uncharacterized maturation process that requires opposing mechanisms of removal and retention of the scaffold protein Anillin. The septin cytoskeleton acts on the C terminus of Anillin to locally trim away excess membrane from the late CR/nascent MR via internalization, extrusion, and shedding, whereas the citron kinase Sticky acts on the N terminus of Anillin to retain it at the mature MR. Simultaneous depletion of septins and Sticky not only disrupted MR formation but also caused earlier CR oscillations, uncovering redundant mechanisms of CR stability that can partly explain the essential role of Anillin in this process. Our findings highlight the relatedness of the CR and MR and suggest that membrane removal is coordinated with CR disassembly.

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