scholarly journals Interactions of PatA with the Divisome during Heterocyst Differentiation in Anabaena

mSphere ◽  
2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Ana Valladares ◽  
Cristina Velázquez-Suárez ◽  
Antonia Herrero
Keyword(s):  
Cell Division ◽  
Organic Nitrogen ◽  
Atmospheric Nitrogen ◽  
Differentiation Process ◽  
Vegetative Cells ◽  
Genetic Changes ◽  
Heterocyst Differentiation ◽  
Essential Components ◽  
Z Ring

ABSTRACT The Anabaena organismic unit is a filament of communicating cells. Under conditions of nitrogen scarcity, some cells along the filament differentiate into heterocysts, which are specialized in the fixation of atmospheric N2 and provide the vegetative cells with N2 fixation products. At a certain stage, the differentiation process becomes irreversible, so that even when nitrogen is replenished, no return to the vegetative cell state takes place, possibly as a consequence of loss of cell division capacity. Upon N-stepdown, midcell FtsZ-rings were detected in vegetative cells, but not in differentiating cells, and this was also the case for ZipN, an essential protein that participates in FtsZ tethering to the cytoplasmic membrane and divisome organization. Later, expression of ftsZ was arrested in mature heterocysts. PatA is a protein required for the differentiation of intercalary heterocysts in Anabaena. The expression level of the patA gene was increased in differentiating cells, and a mutant strain lacking PatA exhibited enhanced FtsZ-rings. PatA was capable of direct interactions with ZipN and SepF, another essential component of the Anabaena Z-ring. Thus, PatA appears to promote inhibition of cell division in the differentiating cells, allowing progress of the differentiation process. PatA, which in mature heterocysts was detected at the cell poles, could interact also with SepJ, a protein involved in production of the septal junctions that provide cell-cell adhesion and intercellular communication in the filament, hinting at a further role of PatA in the formation or stability of the intercellular structures that are at the basis of the multicellular character of Anabaena. IMPORTANCE Anabaena is a cyanobacterial model that represents an ancient and simple form of biological multicellularity. The Anabaena organism is a filament of cohesive and communicating cells that can include cells specialized in different tasks. Thus, under conditions of nitrogen scarcity, certain cells of the filament differentiate into heterocysts, which fix atmospheric nitrogen and provide organic nitrogen to the rest of cells, which, in turn, provide heterocysts with organic carbon. Heterocyst differentiation involves extensive morphological, biochemical, and genetic changes, becoming irreversible at a certain stage. We studied the regulation during heterocyst differentiation of several essential components of the Anabaena cell division machinery and found that protein PatA, which is required for differentiation and is induced in differentiating cells, interacts with essential cell division factors and destabilizes the cell division complex. This suggests a mechanism for establishment of commitment to differentiation by inhibition of cell division.

scholarly journals Requirement of Fra proteins for communication channels between cells in the filamentous nitrogen-fixing cyanobacteriumAnabaenasp. PCC 7120

2015 ◽  
Vol 112 (32) ◽  
pp. E4458-E4464 ◽  
Author(s):  
Amin Omairi-Nasser ◽  
Vicente Mariscal ◽  
Jotham R. Austin ◽  
Robert Haselkorn
Keyword(s):  
Electron Tomography ◽  
Atmospheric Nitrogen ◽  
Channel Formation ◽  
Nitrogen Fixing ◽  
Vegetative Cells ◽  
Metabolite Exchange ◽  
Minor Part ◽  
A Minor ◽  
Pcc 7120

The filamentous nitrogen-fixing cyanobacteriumAnabaenasp. PCC 7120 differentiates specialized cells, heterocysts, that fix atmospheric nitrogen and transfer the fixed nitrogen to adjacent vegetative cells. Reciprocally, vegetative cells transfer fixed carbon to heterocysts. Several routes have been described for metabolite exchange within the filament, one of which involves communicating channels that penetrate the septum between adjacent cells. Severalfragene mutants were isolated 25 y ago on the basis of their phenotypes: inability to fix nitrogen and fragmentation of filaments upon transfer from N+ to N− media. Cryopreservation combined with electron tomography were used to investigate the role of threefragene products in channel formation. FraC and FraG are clearly involved in channel formation, whereas FraD has a minor part. Additionally, FraG was located close to the cytoplasmic membrane and in the heterocyst neck, using immunogold labeling with antibody raised to the N-terminal domain of the FraG protein.

scholarly journals Role of Amphipathic α-helix and Division-related Proteins in Bacillus Subtilis

2020 ◽  
Vol 4 (3) ◽  
Author(s):  
Zehui Zhang ◽  
◽  
Rui Zhang ◽  
Keyword(s):  
Cell Division ◽  
Leading Edge ◽  
Ring Structure ◽  
Dependent Manner ◽  
Membrane Anchor ◽  
Z Ring ◽  
Genetic Techniques ◽  
Α Helix ◽  
Related Proteins

In many bacteria, cell division is initiated by a tubulin-like protein FtsZ, which forms a ring structure known as the Z-ring at midcell. FtsA and SepF are important membrane anchor of Z-ring, which exists widely in bacteria species and binds to the membrane by a C-terminal amphipathic α-helix in a membrane potential-dependent manner. It reported that amphipathic α-helix binds to the leading edge of developing septum with an intrinsic preference. These discoveries led to a hypothesis, proteins of amphipathic helix might not only function as membrane anchor of FtsZ, but also participating the regulation of septum synthesis. Several variants were made by genetic techniques, and cell length measurements were performed by fluorescence microscopy and ImageJ. All helix variants were found viable, the amphipathic α-helix does affect the cell division but does not affect the functionality.

scholarly journals A Diguanylate Cyclase Acts as a Cell Division Inhibitor in a Two-Step Response to Reductive and Envelope Stresses

mBio ◽  
2016 ◽  
Vol 7 (4) ◽  
Author(s):  
Hyo Kyung Kim ◽  
Rasika M. Harshey
Keyword(s):  
Cell Division ◽  
Step Response ◽  
Diguanylate Cyclase ◽  
Division Site ◽  
Envelope Stress ◽  
Z Ring ◽  
A Cell ◽  
Cell Division Inhibitor ◽  
Signal Transduction Systems

ABSTRACT Cell division arrest is a universal checkpoint in response to environmental assaults that generate cellular stress. In bacteria, the cyclic di-GMP (c-di-GMP) signaling network is one of several signal transduction systems that regulate key processes in response to extra-/intracellular stimuli. Here, we find that the diguanylate cyclase YfiN acts as a bifunctional protein that produces c-di-GMP in response to reductive stress and then dynamically relocates to the division site to arrest cell division in response to envelope stress in Escherichia coli . YfiN localizes to the Z ring by interacting with early division proteins and stalls cell division by preventing the initiation of septal peptidoglycan synthesis. These studies reveal a new role for a diguanylate cyclase in responding to environmental change, as well as a novel mechanism for arresting cell division. IMPORTANCE While the major role of c-di-GMP signaling is to control the decision to move freely or settle in a biofilm, recent studies show a broader range of output functions for c-di-GMP signaling. This work reports an unexpected second role for YfiN, a conserved diguanylate cyclase in Gram-negative bacteria, known to contribute to persistence in the host. We find that YfiN acts as a cell division inhibitor in response to envelope stress. Unlike known cell division inhibitors, the interaction of YfiN with cell division proteins retains the Z ring at the midcell but prevents septal invagination. The new function of YfiN not only emphasizes the versatility of c-di-GMP signaling but describes a novel mechanism for a cell division checkpoint.

scholarly journals Assembly of an FtsZ Mutant Deficient in GTPase Activity Has Implications for FtsZ Assembly and the Role of the Z Ring in Cell Division

2001 ◽  
Vol 183 (24) ◽  
pp. 7190-7197 ◽  
Author(s):  
Amit Mukherjee ◽  
Cristian Saez ◽  
Joe Lutkenhaus
Keyword(s):  
Cell Division ◽  
Critical Concentration ◽  
Gtpase Activity ◽  
Support Cell ◽  
Z Ring ◽  
Ftsz Assembly ◽  
The Stability

ABSTRACT FtsZ, the ancestral homologue of eukaryotic tubulins, assembles into the Z ring, which is required for cytokinesis in prokaryotic cells. Both FtsZ and tubulin have a GTPase activity associated with polymerization. Interestingly, the ftsZ2 mutant is viable, although the FtsZ2 mutant protein has dramatically reduced GTPase activity due to a glycine-for-aspartic acid substitution within the synergy loop. In this study, we have examined the properties of FtsZ2 and found that the reduced GTPase activity is not enhanced by DEAE-dextran-induced assembly, indicating it has a defective catalytic site. In the absence of DEAE-dextran, FtsZ2 fails to assemble unless supplemented with wild-type FtsZ. FtsZ has to be at or above the critical concentration for copolymerization to occur, indicating that FtsZ is nucleating the copolymers. The copolymers formed are relatively stable and appear to be stabilized by a GTP-cap. These results indicate that FtsZ2 cannot nucleate assembly in vitro, although it must in vivo. Furthermore, the stability of FtsZ-FtsZ2 copolymers argues that FtsZ2 polymers would be stable, suggesting that stable FtsZ polymers are able to support cell division.

scholarly journals FtsW Is a Dispensable Cell Division Protein Required for Z-Ring Stabilization during Sporulation Septation in Streptomyces coelicolor

2008 ◽  
Vol 190 (16) ◽  
pp. 5555-5566 ◽  
Author(s):  
Bhavesh V. Mistry ◽  
Ricardo Del Sol ◽  
Chris Wright ◽  
Kim Findlay ◽  
Paul Dyson
Keyword(s):  
Cell Division ◽  
Streptomyces Coelicolor ◽  
Cross Wall ◽  
Penicillin Binding Protein ◽  
Aerial Hyphae ◽  
Class B ◽  
Z Ring ◽  
Cell Division Protein

ABSTRACT The conserved rodA and ftsW genes encode polytopic membrane proteins that are essential for bacterial cell elongation and division, respectively, and each gene is invariably linked with a cognate class B high-molecular-weight penicillin-binding protein (HMW PBP) gene. Filamentous differentiating Streptomyces coelicolor possesses four such gene pairs. Whereas rodA, although not its cognate HMW PBP gene, is essential in these bacteria, mutation of SCO5302 or SCO2607 (sfr) caused no gross changes to growth and septation. In contrast, disruption of either ftsW or the cognate ftsI gene blocked the formation of sporulation septa in aerial hyphae. The inability of spiral polymers of FtsZ to reorganize into rings in aerial hyphae of these mutants indicates an early pivotal role of an FtsW-FtsI complex in cell division. Concerted assembly of the complete divisome was unnecessary for Z-ring stabilization in aerial hyphae as ftsQ mutants were found to be blocked at a later stage in cell division, during septum closure. Complete cross wall formation occurred in vegetative hyphae in all three fts mutants, indicating that the typical bacterial divisome functions specifically during nonessential sporulation septation, providing a unique opportunity to interrogate the function and dependencies of individual components of the divisome in vivo.

The Kinney Three Paragraphs (and More) for Accounting Ph.D. Students

2019 ◽  
Vol 33 (4) ◽  
pp. 1-14 ◽  
Author(s):  
William R. Kinney
Keyword(s):  
Review Process ◽  
Student Experiences ◽  
Second Step ◽  
Practical Relevance ◽  
The Third ◽  
Validity Assessment ◽  
Essential Components ◽  
Potential Problems ◽  
Empirical Accounting Research

SYNOPSIS This Commentary is intended to help beginning Ph.D. students identify, evaluate, and communicate essential components of proposed empirical accounting research using a three-step process. The first step is a structured top-down approach of writing answers to three related questions—What, Why, How—that emphasize the central role of conceptual thinking in research design, as well as practical relevance. The second step is a predictive validity assessment that anticipates concerns likely to arise in the scholarly review process, and the third is consideration of the likely outcome and potential problems to be encountered if the proposal is implemented as planned. First-hand accounts of Ph.D. student experiences using the three paragraphs and three-step approach are presented, along with an exercise that beginners can use to help themselves identify, analyze, and anticipate problems to improve chances for research success ex ante.

scholarly journals Small Noncoding RNAs in Knee Osteoarthritis: The Role of MicroRNAs and tRNA-Derived Fragments

2021 ◽  
Vol 22 (11) ◽  
pp. 5711
Author(s):  
Julian Zacharjasz ◽  
Anna M. Mleczko ◽  
Paweł Bąkowski ◽  
Tomasz Piontek ◽  
Kamilla Bąkowska-Żywicka
Keyword(s):  
Knee Osteoarthritis ◽  
Noncoding Rnas ◽  
Pathological Process ◽  
Joint Disease ◽  
Limited Information ◽  
Genetic Changes ◽  
Small Noncoding Rnas ◽  
Knee Oa ◽  
Cartilage Homeostasis

Knee osteoarthritis (OA) is a degenerative knee joint disease that results from the breakdown of joint cartilage and underlying bone, affecting about 3.3% of the world's population. As OA is a multifactorial disease, the underlying pathological process is closely associated with genetic changes in articular cartilage and bone. Many studies have focused on the role of small noncoding RNAs in OA and identified numbers of microRNAs that play important roles in regulating bone and cartilage homeostasis. The connection between other types of small noncoding RNAs, especially tRNA-derived fragments and knee osteoarthritis is still elusive. The observation that there is limited information about small RNAs different than miRNAs in knee OA was very surprising to us, especially given the fact that tRNA fragments are known to participate in a plethora of human diseases and a portion of them are even more abundant than miRNAs. Inspired by these findings, in this review we have summarized the possible involvement of microRNAs and tRNA-derived fragments in the pathology of knee osteoarthritis.

scholarly journals Heart and Mind: Essential Components in Sound Decision-Making

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 364-364
Author(s):  
Michaela Clark ◽  
Julie Hicks Patrick ◽  
Michaela Reardon
Keyword(s):  
Decision Making ◽  
Decision Quality ◽  
Cluster Solution ◽  
Cognitive Resources ◽  
Cluster Membership ◽  
Essential Components ◽  
Decision Making Processes ◽  
Affective Components ◽  
Heart And Mind

Abstract Consumer tasks permit an ecologically-valid context in which to examine the contributions of affective and cognitive resources to decision-making processes and outcomes. Although previous work shows that cognitive factors are important when individuals make decisions (Patrick et al., 2013; Queen et al.), the role of affective components is less clear. We examine these issues in two studies. Study 1 used data from 1000+ adults to inform a cluster analysis examining affective aspects (importance, meaningfulness) of making different types of decisions. A 4-cluster solution resulted. In Study 2, we used affective cluster membership and cognitive performance as predictors of experimental decision-making outcomes among a subset of participants (N = 60). Results of the regression (F(2, 40) = 6.51, p < .01, R2 = .25.) revealed that both the affective clusters (b = .37, p = .01) and cognitive ability (b = -.30, p = .04) uniquely contributed to the variance explained in decision quality. Age did not uniquely contribute. Results are discussed in the context of developing measures that enable us to move the field forward.

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 Molecular Genetics in Epstein–Barr Virus-Associated Malignancies

Life ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 593
Author(s):  
Srikanth Umakanthan ◽  
Maryann M Bukelo
Keyword(s):  
Epstein Barr Virus ◽  
Diagnostic Tools ◽  
Main Role ◽  
Genetic Changes ◽  
Barr Virus ◽  
Cancer Pathogenesis ◽  
Genomic Studies ◽  
Epstein Barr ◽  
Oncogenic Form

Global genomic studies have detected the role of genomic alterations in the pathogenesis of Epstein–Barr virus (EBV)-associated tumors. EBV oncoproteins cause a vital shift of EBV from an infectious virus to an oncogenic form during the latent and lytic phase within the lymphoid B cells and epithelial cells. This epigenetic alteration modulates the virus and host genomes and inactivates and disrupts numerous tumor suppressors and signaling pathways. Genomic profiling has played the main role in identifying EBV cancer pathogenesis and its related targeted therapies. This article reviews the role of genetic changes in EBV-associated lymphomas and carcinomas. This includes the prolific molecular genesis, key diagnostic tools, and target-specific drugs that have been in recent clinical use.

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