scholarly journals DivIVA regulates its expression and the orientation of new septum growth during cell division in Deinococcus radiodurans.

2021 ◽  
Author(s):  
Reema Chaudhary ◽  
Swathi Kota ◽  
Hari S Misra
Keyword(s):  
Cell Division ◽  
Deinococcus Radiodurans ◽  
Gram Negative Bacteria ◽  
Wild Type ◽  
Gram Negative ◽  
Terminal Domain ◽  
Division Site ◽  
Correct Orientation ◽  
Cell Position ◽  
In Trans

In rod shaped Gram-negative bacteria, FtsZ localization at mid cell position is regulated by the gradient of MinCDE complex across the poles. In round shaped bacteria, which lack predefined poles, the next plane of cell division is perpendicular to previous plane and the determination of site for FtsZ assembly is still intriguing. Deinococcus radiodurans, a coccus bacterium, is characterized by its extraordinary resistance to DNA damage. DivIVA, a putative component of Min system in this bacterium, interacts with cognate cell division and genome segregation proteins. Here, we report that deletion of chromosomal copy of DivIVA was possible only when wild type copy of DivIVA was expressed in trans on the plasmid. However, the deletion of C-terminal domain of DivIVA (CTD mutant) was possible but produced distinguishable phenotypes like smaller cells, slower growth and tilted septum orientation in D. radiodurans. In trans expression of DivIVA in CTD mutant could restore these features of wild type. Interestingly, the overexpression of DivIVA led to delayed separation of tetrad from octet state in both trans-complemented divIVA mutant and wild type cells. The CTD mutant showed upregulation of yggS-divIVAN operon. Both wild type and CTD mutant formed FtsZ foci, however unlike wild type, the position of foci in the mutant cells was found to be away from conjectural mid-cell position in cocci. Notably, DivIVA-RFP localizes to septum during cell division at the new division site. These results suggested that DivIVA is an essential protein in D. radiodurans and its C-terminal domain plays an important role in the regulation of its expression and orientation of new septal growth in this bacterium. Importance: In rod-shaped Gram-negative bacteria, the mid-cell position for binary fission is relatively easy to model. In cocci that do not have predefined poles, the plane of next cell division is shown to be perpendicular to the previous plane. However, the molecular basis of perpendicularity is not known in cocci. The DivIVA protein of Deinococcus radiodurans, a coccus bacterium, physically interacts with septum and establishes macromolecular interactions with genome segregation proteins through its N-terminal domain and with MinC through C-terminal domain. Here, we have brought forth some evidence to suggest that DivIVA is essential for growth, plays an important role in cell-polarity determination and its C-terminal domain plays a crucial role in the growth of new septum in correct orientation as well as regulation of its expression.

scholarly journals DivIVA is essential in Deinococcus radiodurans and its C terminal domain regulates new septum orientation during cell division

2020 ◽  
Author(s):  
Reema Chaudhary ◽  
Swathi Kota ◽  
Hari S Misra
Keyword(s):  
Cell Division ◽  
Deinococcus Radiodurans ◽  
Wild Type ◽  
Orthogonal Axis ◽  
Septum Formation ◽  
Terminal Domain ◽  
Cell Position ◽  
Type Pattern ◽  
In Trans ◽  
Ftsz Assembly

AbstractFtsZ assembly at mid cell position in rod shaped bacteria is regulated by gradient of MinCDE complex across the poles. In round shaped bacteria, which lack predefined poles and the next plane of cell division is perpendicular to previous plane, the determination of site for FtsZ assembly is intriguing. Deinococcus radiodurans a coccus shaped bacterium, is characterized for its extraordinary resistance to DNA damage. Here we report that DivIVA a putative component of Min system in this bacterium (drDivIVA) interacts with cognate cell division and genome segregation proteins. The deletion of full length drDivIVA was found to be indispensable while its C-terminal deletion (ΔdivIVAC) was dispensable but produced distinguishable phenotypes like slow growth, altered plane for new septum formation and angular septum. Both wild type and mutant showed FtsZ foci formation and their gamma radiation responses were nearly identical. But unlike in wild type, the FtsZ localization in mutant cells was found to be away from orthogonal axis with respect to plane of previous septum. Notably, DivIVA-RFP localizes to membrane during cell division and then perpendicular to previous plane of cell division. In trans expression of drDivIVA in ΔdivIVAC background could restore the wild type pattern of septum formation perpendicular to previous septum. These results suggested that DivIVA is an essential protein in D. radiodurans and the C-terminal domain that contributes to its interaction with MinC determines the plane of new septum formation, possibly by controlling MinC oscillation through orthogonal axis in the cells.

Constriction and septation during cell division in caulobacters

1981 ◽  
Vol 27 (7) ◽  
pp. 704-719 ◽  
Author(s):  
J. S. Poindexter ◽  
J. G. Hagenzieker
Keyword(s):  
Cell Division ◽  
Bacterial Strain ◽  
Gram Negative Bacteria ◽  
Developmental Difference ◽  
Gram Negative ◽  
Division Site ◽  
A Site

Morphogenesis of the division site in caulobacters had been described as constrictive in Caulobacter spp. and septate in Asticcacaulis excentricus. However, subsequent studies of other gram-negative genera had implied that constrictive division was an artefact resulting from inadequate preservation of septa; exploration of alternatives to osmium fixation, particularly with aldehydes, was recommended. In this study, the appearance of sectioned division sites was reinvestigated in caulobacter cells prepared by 20 different procedures varying with respect to fixation agents, media, schedules, and temperatures, to dehydrating agents, and to embedding resins. Three types of division site morphogenesis were observed: constriction in C. bacteroides and C. crescentus, partial septation in C. leidyi, and complete, undivided septation in A. excentricus and A. biprosthecum. The anatomy of the division site depended on the bacterial strain, not on the method of preparation of the cells for sectioning. These studies confirm the earlier observations on osmium-fixed caulobacter cells and lead to the general conclusion that gram-negative bacteria with tapered poles probably divide by constriction, whereas septation results in blunt cell poles. A pattern of spiral, rather than circular, insertion of new envelope subunits at the cell equator is proposed as a basic developmental difference between constrictive and septate fission in gram-negative bacteria. Since caulobacter prosthecae can develop as extensions of tapered poles formed by constriction, whereas subpolar or lateral prosthecae occur in species with blunt poles resulting from septation, the site of formation of a thick septum appears unsuitable as a site of subsequent envelope outgrowth.

scholarly journals MexAB-OprM Efflux Pump Interaction with the Peptidoglycan of Escherichia coli and Pseudomonas aeruginosa

2021 ◽  
Vol 22 (10) ◽  
pp. 5328
Author(s):  
Miao Ma ◽  
Margaux Lustig ◽  
Michèle Salem ◽  
Dominique Mengin-Lecreulx ◽  
Gilles Phan ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Cell Division ◽  
Membrane Proteins ◽  
Outer Membrane ◽  
Efflux Pump ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Active Efflux

One of the major families of membrane proteins found in prokaryote genome corresponds to the transporters. Among them, the resistance-nodulation-cell division (RND) transporters are highly studied, as being responsible for one of the most problematic mechanisms used by bacteria to resist to antibiotics, i.e., the active efflux of drugs. In Gram-negative bacteria, these proteins are inserted in the inner membrane and form a tripartite assembly with an outer membrane factor and a periplasmic linker in order to cross the two membranes to expulse molecules outside of the cell. A lot of information has been collected to understand the functional mechanism of these pumps, especially with AcrAB-TolC from Escherichia coli, but one missing piece from all the suggested models is the role of peptidoglycan in the assembly. Here, by pull-down experiments with purified peptidoglycans, we precise the MexAB-OprM interaction with the peptidoglycan from Escherichia coli and Pseudomonas aeruginosa, highlighting a role of the peptidoglycan in stabilizing the MexA-OprM complex and also differences between the two Gram-negative bacteria peptidoglycans.

scholarly journals Shadowing the Actions of a Predator: Backlit Fluorescent Microscopy Reveals Synchronous Nonbinary Septation of Predatory Bdellovibrio inside Prey and Exit through Discrete Bdelloplast Pores

2010 ◽  
Vol 192 (24) ◽  
pp. 6329-6335 ◽  
Author(s):  
A. K. Fenton ◽  
M. Kanna ◽  
R. D. Woods ◽  
S.-I. Aizawa ◽  
R. E. Sockett
Keyword(s):  
Cell Division ◽  
Outer Membrane ◽  
Fluorescent Microscopy ◽  
Gram Negative Bacteria ◽  
Bacterial Cell Division ◽  
Prey Cell ◽  
Gram Negative ◽  
A Genome ◽  
Predatory Bacteria ◽  
First Time

ABSTRACT The Bdellovibrio are miniature “living antibiotic” predatory bacteria which invade, reseal, and digest other larger Gram-negative bacteria, including pathogens. Nutrients for the replication of Bdellovibrio bacteria come entirely from the digestion of the single invaded bacterium, now called a bdelloplast, which is bound by the original prey outer membrane. Bdellovibrio bacteria are efficient digesters of prey cells, yielding on average 4 to 6 progeny from digestion of a single prey cell of a genome size similar to that of the Bdellovibrio cell itself. The developmental intrabacterial cycle of Bdellovibrio is largely unknown and has never been visualized “live.” Using the latest motorized xy stage with a very defined z-axis control and engineered periplasmically fluorescent prey allows, for the first time, accurate return and visualization without prey bleaching of developing Bdellovibrio cells using solely the inner resources of a prey cell over several hours. We show that Bdellovibrio bacteria do not follow the familiar pattern of bacterial cell division by binary fission. Instead, they septate synchronously to produce both odd and even numbers of progeny, even when two separate Bdellovibrio cells have invaded and develop within a single prey bacterium, producing two different amounts of progeny. Evolution of this novel septation pattern, allowing odd progeny yields, allows optimal use of the finite prey cell resources to produce maximal replicated, predatory bacteria. When replication is complete, Bdellovibrio cells exit the exhausted prey and are seen leaving via discrete pores rather than by breakdown of the entire outer membrane of the prey.

scholarly journals Role of Autocleavage in the Function of a Type III Secretion Specificity Switch Protein in Salmonella enterica Serovar Typhimurium

mBio ◽  
2015 ◽  
Vol 6 (5) ◽  
Author(s):  
Julia V. Monjarás Feria ◽  
Matthew D. Lefebre ◽  
York-Dieter Stierhof ◽  
Jorge E. Galán ◽  
Samuel Wagner
Keyword(s):  
Host Cell ◽  
Type Iii Secretion ◽  
Effector Proteins ◽  
Switching Function ◽  
Gram Negative Bacteria ◽  
Wild Type ◽  
Gram Negative ◽  
Type Iii ◽  
Autocatalytic Cleavage ◽  
Serovar Typhimurium

ABSTRACTType III secretion systems (T3SSs) are multiprotein machines employed by many Gram-negative bacteria to inject bacterial effector proteins into eukaryotic host cells to promote bacterial survival and colonization. The core unit of T3SSs is the needle complex, a supramolecular structure that mediates the passage of the secreted proteins through the bacterial envelope. A distinct feature of the T3SS is that protein export occurs in a strictly hierarchical manner in which proteins destined to form the needle complex filament and associated structures are secreted first, followed by the secretion of effectors and the proteins that will facilitate their translocation through the target host cell membrane. The secretion hierarchy is established by complex mechanisms that involve several T3SS-associated components, including the “switch protein,” a highly conserved, inner membrane protease that undergoes autocatalytic cleavage. It has been proposed that the autocleavage of the switch protein is the trigger for substrate switching. We show here that autocleavage of theSalmonella entericaserovar Typhimurium switch protein SpaS is an unregulated process that occurs after its folding and before its incorporation into the needle complex. Needle complexes assembled with a precleaved form of SpaS function in a manner indistinguishable from that of the wild-type form. Furthermore, an engineered mutant of SpaS that is processed by an external protease also displays wild-type function. These results demonstrate that the cleavage eventper sedoes not provide a signal for substrate switching but support the hypothesis that cleavage allows the proper conformation of SpaS to render it competent for its switching function.IMPORTANCEBacterial interaction with eukaryotic hosts often involves complex molecular machines for targeted delivery of bacterial effector proteins. One such machine, the type III secretion system of some Gram-negative bacteria, serves to inject a multitude of structurally diverse bacterial proteins into the host cell. Critical to the function of these systems is their ability to secrete proteins in a strict hierarchical order, but it is unclear how the mechanism of switching works. Central to the switching mechanism is a highly conserved inner membrane protease that undergoes autocatalytic cleavage. Although it has been suggested previously that the autocleavage event is the trigger for substrate switching, we show here that this is not the case. Rather, our results show that cleavage allows the proper conformation of the protein to render it competent for its switching function. These findings may help develop inhibitors of type III secretion machines that offer novel therapeutic avenues to treat various infectious diseases.

Fine structural observations of Desulfovibrio desulfuricans

1973 ◽  
Vol 19 (6) ◽  
pp. 753-756
Author(s):  
Terrence M. Hammill ◽  
Geno J. Germano
Keyword(s):  
Electron Microscopy ◽  
Cell Division ◽  
Cell Envelope ◽  
Desulfovibrio Desulfuricans ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Ultrathin Sections ◽  
Basal Apparatus ◽  
Specialized Region ◽  
Whole Mounts

Glutaraldehyde-fixed, platinum-carbon-shadowed whole mounts, and ultrathin sections of glutaraldehyde-OsO4-fixed cells of Desulfovibrio desulfuricans were observed by electron microscopy. The preparations demonstrated a typical Vibrio form with a single polar flagellum. The cell envelope and the formation of external blebs were shown to be similar to other gram-negative bacteria. The protoplast, apparently devoid of mesosomes or other membranous structures, was densely packed with ribosomes and contained a fibrous nucleoid. A specialized region near the flagellar end of the cell was commonly observed and termed the basal apparatus. Cell division appeared to be by constriction.

scholarly journals Mining of Gram-Negative Surface-Active Enzybiotic Candidates by Sequence-Based Calculation of Physicochemical Properties

2021 ◽  
Vol 12 ◽  
Author(s):  
Roberto Vázquez ◽  
Sofía Blanco-Gañán ◽  
Susana Ruiz ◽  
Pedro García
Keyword(s):  
Physicochemical Properties ◽  
Nearest Neighbors ◽  
Regulatory Agencies ◽  
Gram Negative Bacteria ◽  
Wild Type ◽  
Gram Negative ◽  
Bacterial Surface ◽  
Negative Surface ◽  
Surface Active ◽  
Phage Lysins

Phage (endo)lysins are nowadays one of the most promising ways out of the current antibiotic resistance crisis. Either as sole therapeutics or as a complement to common antibiotic chemotherapy, lysins are already entering late clinical phases to get regulatory agencies’ authorization. Even the old paradigm of the inability of lysins to attack Gram-negative bacteria from without has already been overcome in a variety of ways: either by engineering approaches or investigating the natural mechanisms by which some wild-type lysins are able to interact with the bacterial surface. Such inherent ability of some lysins has been linked to antimicrobial peptide (AMP)-like regions, which are, on their own, a significant source for novel antimicrobials. Currently, though, many of the efforts for searching novel lysin-based antimicrobial candidates rely on experimental screenings. In this work, we have bioinformatically analyzed the C-terminal end of a collection of lysins from phages infecting the Gram-negative genus Pseudomonas. Through the computation of physicochemical properties, the probability of such regions to be an AMP was estimated by means of a predictive k-nearest neighbors (kNN) model. This way, a subset of putatively membrane-interacting lysins was obtained from the original database. Two of such candidates (named Pae87 and Ppl65) were prospectively tested in terms of muralytic, bacteriolytic, and bactericidal activity. Both of them were found to possess an activity against Pseudomonas aeruginosa and other Gram-negative bacterial pathogens, implying that the prediction of AMP-like regions could be a useful approach toward the mining of phage lysins to design and develop antimicrobials or antimicrobial parts for further engineering.

scholarly journals Analysis of MinC Reveals Two Independent Domains Involved in Interaction with MinD and FtsZ

2000 ◽  
Vol 182 (14) ◽  
pp. 3965-3971 ◽  
Author(s):  
Zonglin Hu ◽  
Joe Lutkenhaus
Keyword(s):  
Escherichia Coli ◽  
Cell Division ◽  
Functional Domains ◽  
Wild Type ◽  
Terminal Domain ◽  
Ring Assembly ◽  
Z Ring ◽  
Ftsz Assembly

ABSTRACT In Escherichia coli FtsZ assembles into a Z ring at midcell while assembly at polar sites is prevented by themin system. MinC, a component of this system, is an inhibitor of FtsZ assembly that is positioned within the cell by interaction with MinDE. In this study we found that MinC consists of two functional domains connected by a short linker. When fused to MalE the N-terminal domain is able to inhibit cell division and prevent FtsZ assembly in vitro. The C-terminal domain interacts with MinD, and expression in wild-type cells as a MalE fusion disrupts minfunction, resulting in a minicell phenotype. We also find that MinC is an oligomer, probably a dimer. Although the C-terminal domain is clearly sufficient for oligomerization, the N-terminal domain also promotes oligomerization. These results demonstrate that MinC consists of two independently functioning domains: an N-terminal domain capable of inhibiting FtsZ assembly and a C-terminal domain responsible for localization of MinC through interaction with MinD. The fusion of these two independent domains is required to achieve topological regulation of Z ring assembly.

scholarly journals Mutational Analysis of the TolA C-Terminal Domain of Escherichia coli and Genetic Evidence for an Interaction between TolA and TolB

2002 ◽  
Vol 184 (16) ◽  
pp. 4620-4625 ◽  
Author(s):  
Jean François Dubuisson ◽  
Anne Vianney ◽  
Jean Claude Lazzaroni
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Mutational Analysis ◽  
Membrane Stability ◽  
Genetic Evidence ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Terminal Domain ◽  
Suppressor Mutants

ABSTRACT The Tol proteins are involved in the outer membrane stability of gram-negative bacteria. The C-terminal domain of TolA was mutagenized to identify residues important for its functions. The isolation of suppressor mutants of tolA mutations in the tolB gene confirmed an interaction between TolAIII and the N-terminal domain of TolB.

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