scholarly journals Genomic contacts reveal the control of sister chromosome decatenation in E. coli

2021 ◽  
Author(s):  
Brenna Conin ◽  
Ingrid Billault-Chaumartin ◽  
Hafez El Sayyed ◽  
Charlotte Cockram ◽  
Romain Koszul ◽  
...  
Keyword(s):  
Genetic Analysis ◽  
Chromosome Segregation ◽  
Large Scale ◽  
Topoisomerase Iv ◽  
E Coli ◽  
Conformation Changes ◽  
Sister Chromatids ◽  
Sister Chromosome ◽  
In Trans

In bacteria, chromosome segregation occurs progressively, from the origin to the terminus, a few minutes after the replication of each locus. In-between replication and segregation, sister loci are maintained in an apparent cohesive state by topological links. Whereas topoisomerase IV (Topo IV), the main bacteria decatenase, controls segregation, little is known regarding the influence of the cohesion step on chromosome folding. In this work, we investigated chromosome folding in cells with altered decatenation activities. Within minutes after Topo IV inactivation, a massive chromosome reorganization takes place, associated with increases in trans-contacts between catenated sister chromatids and in long-range cis-contacts between the terminus and distant loci on the genome. A genetic analysis of these signals allowed us to decipher specific roles for Topo IV and Topo III, an accessory decatenase. Moreover we revealed the role of MatP, the terminus macrodomain organizing system and MukB, the E. coli SMC in organizing sister chromatids tied by persistent catenation links . We propose that large-scale conformation changes observed in these conditions reveal a defective decatenation hub located in the terminus area. Altogether, our findings support a model of spatial and temporal partition of the tasks required for sister chromosome segregation.

SATP (YaaH), a succinate–acetate transporter protein in Escherichia coli

2013 ◽  
Vol 454 (3) ◽  
pp. 585-595 ◽  
Author(s):  
Joana Sá-Pessoa ◽  
Sandra Paiva ◽  
David Ribas ◽  
Inês Jesus Silva ◽  
Sandra Cristina Viegas ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Acetic Acid ◽  
Succinic Acid ◽  
Critical Role ◽  
Amino Acid Residues ◽  
E Coli ◽  
Transporter Protein ◽  
Affinity Constants ◽  
In Trans

In the present paper we describe a new carboxylic acid transporter in Escherichia coli encoded by the gene yaaH. In contrast to what had been described for other YaaH family members, the E. coli transporter is highly specific for acetic acid (a monocarboxylate) and for succinic acid (a dicarboxylate), with affinity constants at pH 6.0 of 1.24±0.13 mM for acetic acid and 1.18±0.10 mM for succinic acid. In glucose-grown cells the ΔyaaH mutant is compromised for the uptake of both labelled acetic and succinic acids. YaaH, together with ActP, described previously as an acetate transporter, affect the use of acetic acid as sole carbon and energy source. Both genes have to be deleted simultaneously to abolish acetate transport. The uptake of acetate and succinate was restored when yaaH was expressed in trans in ΔyaaH ΔactP cells. We also demonstrate the critical role of YaaH amino acid residues Leu131 and Ala164 on the enhanced ability to transport lactate. Owing to its functional role in acetate and succinate uptake we propose its assignment as SatP: the Succinate–Acetate Transporter Protein.

Families, Funerals and Facebook: Reimag(in)ing and ‘Curating’ Toraja Kin in Trans-local Times

2015 ◽  
Vol 3 (2) ◽  
pp. 239-266 ◽  
Author(s):  
Kathleen M. Adams
Keyword(s):  
Social Media ◽  
Large Scale ◽  
Local Times ◽  
Funeral Rites ◽  
Familial Relationships ◽  
Familial Bonds ◽  
Non Local ◽  
In Trans ◽  
Anthropological Literature

AbstractThe Sa'dan Toraja of upland Sulawesi, Indonesia have long been celebrated in the anthropological literature for their elaborate procession-filled mortuary rituals, which draw vast networks of kith and kin to mourn, memorialise, and reaffirm familial bonds and obligations. Whether residing in the homeland or abroad, most Torajans underscore funeral rites as the most vital expression of Toraja familial and cultural identity. Although some estimates suggest that more Torajans now reside off-island and overseas than remain in the homeland, extended familial funerals in the homeland continue to have a centripetal physical, economic and emotional pull. While various scholars have documented the ways in which remittances from Toraja migrants or the presence of international tourists have transformed Toraja funerals in recent decades, this article focusses on the role of social media in navigating global familial relationships and rituals. Indonesia has the largest number of Facebook subscribers in the world, and this study offers the first exploration of the ways in which Facebook interweaves far-flung familial relationships. This study also examines house-society orientations in the Toraja highlands and addresses the use of Facebook by Torajans in the homeland to cultivate continued allegiances to ancestral houses (around which extended Toraja families are oriented). Finally, this article also examines a large-scale 2012 Toraja funeral in order to spotlight the contours of the Toraja family in the current era of neoliberalism and cyber-technologies. The article offers insights into the ways in which various Torajans navigate social media and non-local corporations to image, reimagine and negotiate familial identities for various audiences (local, national and transnational).

scholarly journals Intermediates in the assembly of mitotic checkpoint complexes and their role in the regulation of the anaphase-promoting complex

2016 ◽  
Vol 113 (4) ◽  
pp. 966-971 ◽  
Author(s):  
Sharon Kaisari ◽  
Danielle Sitry-Shevah ◽  
Shirly Miniowitz-Shemtov ◽  
Avram Hershko
Keyword(s):  
Chromosome Segregation ◽  
Mitotic Spindle ◽  
Spindle Assembly Checkpoint ◽  
Mitotic Checkpoint ◽  
Anaphase Promoting Complex ◽  
Checkpoint Proteins ◽  
Sister Chromatids ◽  
Unknown Species ◽  
Mitotic Checkpoint Complex

The mitotic (or spindle assembly) checkpoint system prevents premature separation of sister chromatids in mitosis and thus ensures the fidelity of chromosome segregation. Kinetochores that are not attached properly to the mitotic spindle produce an inhibitory signal that prevents progression into anaphase. The checkpoint system acts on the Anaphase-Promoting Complex/Cyclosome (APC/C) ubiquitin ligase, which targets for degradation inhibitors of anaphase initiation. APC/C is inhibited by the Mitotic Checkpoint Complex (MCC), which assembles when the checkpoint is activated. MCC is composed of the checkpoint proteins BubR1, Bub3, and Mad2, associated with the APC/C coactivator Cdc20. The intermediary processes in the assembly of MCC are not sufficiently understood. It is also not clear whether or not some subcomplexes of MCC inhibit the APC/C and whether Mad2 is required only for MCC assembly and not for its action on the APC/C. We used purified subcomplexes of mitotic checkpoint proteins to examine these problems. Our results do not support a model in which Mad2 catalytically generates a Mad2-free APC/C inhibitor. We also found that the release of Mad2 from MCC caused a marked (although not complete) decrease in inhibitory action, suggesting a role of Mad2 in MCC for APC/C inhibition. A previously unknown species of MCC, which consists of Mad2, BubR1, and two molecules of Cdc20, contributes to the inhibition of APC/C by the mitotic checkpoint system.

scholarly journals Role of AmpC-Inducing Genes in Modulating Other Serine Beta-Lactamases in Escherichia coli

Antibiotics ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 67
Author(s):  
Dhriti Mallik ◽  
Diamond Jain ◽  
Sanjib Bhakta ◽  
Anindya Sundar Ghosh
Keyword(s):  
Negative Regulator ◽  
Beta Lactamase ◽  
Beta Lactam ◽  
Beta Lactamases ◽  
E Coli ◽  
Global Challenge ◽  
Induction Mechanism ◽  
In Trans ◽  
Key Genes

The consistently mutating bacterial genotypes appear to have accelerated the global challenge with antimicrobial resistance (AMR); it is therefore timely to investigate certain less-explored fields of targeting AMR mechanisms in bacterial pathogens. One of such areas is beta-lactamase (BLA) induction that can provide us with a collection of prospective therapeutic targets. The key genes (ampD, ampE and ampG) to which the AmpC induction mechanism is linked are also involved in regulating the production of fragmented muropeptides generated during cell-wall peptidoglycan recycling. Although the involvement of these genes in inducing class C BLAs is apparent, their effect on serine beta-lactamase (serine-BLA) induction is little known. Here, by using ∆ampD and ∆ampE mutants of E. coli, we attempted to elucidate the effects of ampD and ampE on the expression of serine-BLAs originating from Enterobacteriaceae, viz., CTX-M-15, TEM-1 and OXA-2. Results show that cefotaxime is the preferred inducer for CTX-M-15 and amoxicillin for TEM-1, whereas oxacillin for OXA-2. Surprisingly, exogenous BLA expressions are elevated in ∆ampD and ∆ampE mutants but do not always alter their beta-lactam susceptibility. Moreover, the beta-lactam resistance is increased upon in trans expression of ampD, whereas the same is decreased upon ampE expression, indicating a differential effect of ampD and ampE overexpression. In a nutshell, depending on the BLA, AmpD amidase moderately facilitates a varying level of serine-BLA expression whereas AmpE transporter acts likely as a negative regulator of serine-BLA.

scholarly journals Aurora B Tension Sensing Mechanisms in the Kinetochore Ensure Accurate Chromosome Segregation

2021 ◽  
Vol 22 (16) ◽  
pp. 8818
Author(s):  
Shelby L. McVey ◽  
Jenna K. Cosby ◽  
Natalie J. Nannas
Keyword(s):  
Chromosome Segregation ◽  
Birth Defects ◽  
Spindle Assembly Checkpoint ◽  
Spindle Assembly ◽  
Aurora B ◽  
Sister Chromatids ◽  
Congenital Birth Defects ◽  
Biochemical Signals ◽  
Segregation Of Chromosomes

The accurate segregation of chromosomes is essential for the survival of organisms and cells. Mistakes can lead to aneuploidy, tumorigenesis and congenital birth defects. The spindle assembly checkpoint ensures that chromosomes properly align on the spindle, with sister chromatids attached to microtubules from opposite poles. Here, we review how tension is used to identify and selectively destabilize incorrect attachments, and thus serves as a trigger of the spindle assembly checkpoint to ensure fidelity in chromosome segregation. Tension is generated on properly attached chromosomes as sister chromatids are pulled in opposing directions but resisted by centromeric cohesin. We discuss the role of the Aurora B kinase in tension-sensing and explore the current models for translating mechanical force into Aurora B-mediated biochemical signals that regulate correction of chromosome attachments to the spindle.

scholarly journals Effects of a Mutation in thegyrAGene on the Virulence of Uropathogenic Escherichia coli

2015 ◽  
Vol 59 (8) ◽  
pp. 4662-4668 ◽  
Author(s):  
Javier Sánchez-Céspedes ◽  
Emma Sáez-López ◽  
N. Frimodt-Møller ◽  
Jordi Vila ◽  
Sara M. Soto
Keyword(s):  
Escherichia Coli ◽  
Bacterial Infections ◽  
Dna Supercoiling ◽  
Uropathogenic Escherichia Coli ◽  
Topoisomerase Iv ◽  
Content Type ◽  
E Coli ◽  
Type Gene ◽  
Encoding Genes

ABSTRACTFluoroquinolones are among the drugs most extensively used for the treatment of bacterial infections in human and veterinary medicine. Resistance to quinolones can be chromosome or plasmid mediated. The chromosomal mechanism of resistance is associated with mutations in the DNA gyrase- and topoisomerase IV-encoding genes and mutations in regulatory genes affecting different efflux systems, among others. We studied the role of the acquisition of a mutation in thegyrAgene in the virulence and protein expression of uropathogenicEscherichia coli(UPEC). The HC14366M strain carrying a mutation in thegyrAgene (S83L) was found to lose the capacity to cause cystitis and pyelonephritis mainly due to a decrease in the expression of thefimA,papA,papB, andompAgenes. The levels of expression of thefimA,papB, andompAgenes were recovered on complementing the strain with a plasmid containing thegyrAwild-type gene. However, only a slight recovery was observed in the colonization of the bladder in the GyrA complement strain compared to the mutant strain in a murine model of ascending urinary tract infection. In conclusion, a mutation in thegyrAgene of uropathogenicE. colireduced the virulence of the bacteria, likely in association with the effect of DNA supercoiling on the expression of several virulence factors and proteins, thereby decreasing their capacity to cause cystitis and pyelonephritis.

scholarly journals The role of FIS in trans activation of stable RNA operons of E. coli.

1990 ◽  
Vol 9 (3) ◽  
pp. 727-734 ◽  
Author(s):  
L. Nilsson ◽  
A. Vanet ◽  
E. Vijgenboom ◽  
L. Bosch
Keyword(s):  
E Coli ◽  
In Trans

scholarly journals Role of the Extended α4 Domain of Staphylococcus aureus Gyrase A Protein in Determining Low Sensitivity to Quinolones

2006 ◽  
Vol 50 (2) ◽  
pp. 600-606 ◽  
Author(s):  
Jacob Strahilevitz ◽  
Ari Robicsek ◽  
David C. Hooper
Keyword(s):  
Staphylococcus Aureus ◽  
Acquired Resistance ◽  
Dna Gyrase ◽  
Wild Type ◽  
Topoisomerase Iv ◽  
E Coli ◽  
Gyrase A ◽  
Low Sensitivity ◽  
Emergence Of Resistance

ABSTRACT Fluoroquinolones target two bacterial type II topoisomerases, DNA gyrase and topoisomerase IV. Acquired resistance to quinolones occurs stepwise, with the first mutation occurring in the more sensitive target enzyme. To limit the emergence of resistance, quinolones should ideally possess dual activities against the two enzymes. For reasons that are as yet unclear, Staphylococcus aureus gyrase is less sensitive to quinolones than topoisomerase IV, counter to its greater sensitivity in Escherichia coli, thereby limiting the use of quinolones for the treatment of staphylococcal infections. Mutations in the α4-helix domain of the GyrA subunit of gyrase are important in determining quinolone resistance. We replaced an extended region encompassing the α4 domain in the E. coli GyrA protein with its homolog in S. aureus and tested for its ability to complement a thermosensitive gyrase and its catalytic and noncatalytic properties. Purified gyrase reconstituted with chimeric GyrA was more resistant to ciprofloxacin than wild-type gyrase at both inhibition of catalytic activity and stimulation of cleavage complexes, and this difference was more apparent in the presence of K+-glutamate. The chimeric GyrA subunit was able to complement thermosensitive gyrase, similar to wild-type GyrA. Without supplemental K+-glutamate the MICs of ciprofloxacin for thermosensitive E. coli complemented with chimeric DNA gyrase were equal to those for E. coli complemented with wild-type gyrase but were twofold higher in the presence of K+-glutamate. Our findings suggest that the extended α4 domain of S. aureus GyrA is responsible, at least in part, for the increased resistance of S. aureus gyrase to quinolones and that this effect is modulated by K+-glutamate.

scholarly journals Genetic evidence for a role of parC mutations in development of high-level fluoroquinolone resistance in Escherichia coli.

1996 ◽  
Vol 40 (4) ◽  
pp. 879-885 ◽  
Author(s):  
P Heisig
Keyword(s):  
Escherichia Coli ◽  
Fluoroquinolone Resistance ◽  
Gyra Gene ◽  
Topoisomerase Iv ◽  
E Coli ◽  
Resistant Strains ◽  
Gyra Mutation ◽  
High Level ◽  
Moderately Resistant

Fifteen strains of Escherichia coli with MICs of ciprofloxacin (CIP) between 0.015 and 256 micrograms/ml were examined for the presence of mutations in the quinolone resistance-determining region of the gyrA gene and in an analogous region of the parC gene. No mutation was found in a susceptible isolate (MIC of CIP, 0.015 microgram/ml). Four moderately resistant strains (MIC of CIP 0.06 to 4 micrograms/ml) carried one gyrA mutation affecting serine 83, but in only one strain was an additional parC mutation (Gly-78 to Asp) detected. All ten highly resistant strains examined (MIC of CIP, > 4 micrograms/ml) carried two gyrA mutations affecting residues serine 83 and aspartate 87, and at least one parC mutation. These parC mutations included alterations of serine 80 to arginine or isoleucine and glutamate 84 to glycine or lysine. The parC+ and two mutant alleles (parCI-80 and parCI-80,G-84) were inserted into the mobilizable vector pBP507. Transfer of a plasmid-coded parC+ allele into parC+ strains did not alter the susceptibilities towards ciprofloxacin or nalidixic acid, while a significant increase in susceptibility was detectable for parC mutants. This increase, however, did not restore wild-type susceptibility, whereas transfer of a plasmid-coded gyrA+ allele alone or in combination with parC+ did. These data are in agreement with the view that topoisomerase IV is a secondary, less sensitive target for quinolone action in Escherichia coli and that the development of high-level fluoroquinolone resistance in E. coli requires at least one parC mutation in addition to the gyrA mutation(s).

Immunogold labeling of CMP-KDO synthetase produced by recombinant E. Coli cells

1987 ◽  
Vol 45 ◽  
pp. 924-925
Author(s):  
F. A. Durum ◽  
R. G. Goldman ◽  
T. J. Bolling ◽  
M. F. Miller
Keyword(s):  
Inclusion Bodies ◽  
Large Scale ◽  
Recombinant Dna ◽  
Test System ◽  
Cell Protein ◽  
Gram Negative Bacteria ◽  
Cytoplasmic Inclusions ◽  
Isolation And Purification ◽  
E Coli ◽  
Low Concentrations

CMP-KDO synthetase (CKS) is an enzyme which plays a key role in the synthesis of LPS, an outer membrane component unique to gram negative bacteria. CKS activates KDO to CMP-KDO for incorporation into LPS. The enzyme is normally present in low concentrations (0.02% of total cell protein) which makes it difficult to perform large scale isolation and purification. Recently, the gene for CKS from E. coli was cloned and various recombinant DNA constructs overproducing CKS several thousandfold (unpublished data) were derived. Interestingly, no cytoplasmic inclusions of overproduced CKS were observed by EM (Fig. 1) which is in contrast to other reports of large proteinaceous inclusion bodies in various overproducing recombinant strains. The present immunocytochemical study was undertaken to localize CKS in these cells.Immune labeling conditions were first optimized using a previously described cell-free test system. Briefly, this involves soaking small blocks of polymerized bovine serum albumin in purified CKS antigen and subjecting them to various fixation, embedding and immunochemical conditions.

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