scholarly journals Import of the Transfer RNase Colicin D Requires Site-Specific Interaction with the Energy-Transducing Protein TonB

2005 ◽  
Vol 187 (8) ◽  
pp. 2693-2697 ◽  
Author(s):  
Liliana Mora ◽  
Nancy Diaz ◽  
Richard H. Buckingham ◽  
Miklos de Zamaroczy
Keyword(s):  
Outer Membrane ◽  
Specific Interaction ◽  
Side Chains ◽  
Uptake Capacity ◽  
Site Specific ◽  
Suppressor Mutations ◽  
Colicin B ◽  
Terminal Domains

ABSTRACT The transfer RNase colicin D and ionophoric colicin B appropriate the outer membrane iron siderophore receptor FepA and share a common translocation requirement for the TonB pathway to cross the outer membrane. Despite the almost identical sequences of the N-terminal domains required for the translocation of colicins D and B, two spontaneous tonB mutations (Arg158Ser and Pro161Leu) completely abolished colicin D toxicity but did not affect either the sensitivity to other colicins or the FepA-dependent siderophore uptake capacity. The sensitivity to colicin D of both tonB mutants was fully restored by specific suppressor mutations in the TonB box of colicin D, at Ser18(Thr) and Met19(Ile), respectively. This demonstrates that the interaction of colicin D with TonB is critically dependent on certain residues close to position 160 in TonB and on the side chains of certain residues in the TonB box of colicin D. The effect of introducing the TonB boxes from other TonB-dependent receptors and colicins into colicins D and B was studied. The results of these and other changes in the two TonB boxes show that the role of residues at positions 18 and 19 in colicin D is strongly modulated by other nearby and/or distant residues and that the overall function of colicin D is much more dependent on the interaction with TonB involving the TonB box than is the function of colicin B.

scholarly journals Role of TolR N-Terminal, Central, and C-Terminal Domains in Dimerization and Interaction with TolA and TolQ

1999 ◽  
Vol 181 (15) ◽  
pp. 4476-4484 ◽  
Author(s):  
Laure Journet ◽  
Alain Rigal ◽  
Claude Lazdunski ◽  
Hélène Bénédetti
Keyword(s):  
Outer Membrane ◽  
Cytoplasmic Membrane ◽  
Transmembrane Domain ◽  
Cell Envelope ◽  
Cross Linking ◽  
Deletion Mutants ◽  
Membrane Complex ◽  
Phage Dna ◽  
Terminal Domains

ABSTRACT The Tol-PAL system of Escherichia coli is a multiprotein system involved in maintaining the cell envelope integrity and is necessary for the import of some colicins and phage DNA into the bacterium. It is organized into two complexes, one near the outer membrane between TolB and PAL and one in the cytoplasmic membrane between TolA, TolQ, and TolR. In the cytoplasmic membrane, all of the Tol proteins have been shown to interact with each other. Cross-linking experiments have shown that the TolA transmembrane domain interacts with TolQ and TolR. Suppressor mutant analyses have localized the TolQ-TolA interaction to the first transmembrane domain of TolQ and have shown that the third transmembrane domain of TolQ interacts with the transmembrane domain of TolR. To get insights on the composition of the cytoplasmic membrane complex and its possible contacts with the outer membrane complex, we focused our attention on TolR. Cross-linking and immunoprecipitation experiments allowed the identification of Tol proteins interacting with TolR. The interactions of TolR with TolA and TolQ were confirmed, TolR was shown to dimerize, and the resulting dimer was shown to interact with TolQ. Deletion mutants of TolR were constructed, and they allowed us to determine the TolR domains involved in each interaction. The TolR transmembrane domain was shown to be involved in the TolA-TolR and TolQ-TolR interactions, while TolR central and C-terminal domains appeared to be involved in TolR dimerization. The role of the TolR C-terminal domain in the TolA-TolR interaction and its association with the membranes was also demonstrated. Furthermore, phenotypic studies clearly showed that the three TolR domains (N terminal, central, and C terminal) and the level of TolR production are important for colicin A import and for the maintenance of cell envelope integrity.

A ROLE OF PROTEINS OF THE OUTER MEMBRANE OF Shewanella oneidensis MR-1 BACTERIA IN FORMATION AND STABILIZATION OF SILVER SULFIDE NANOPARTICLES

2015 ◽  
pp. 41-48 ◽  
Author(s):  
T. A. Voeikova ◽  
A. S. Shebanova ◽  
Yu. D. Ivanov ◽  
A. L. Kaysheva ◽  
L. M. Novikova ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Shewanella Oneidensis ◽  
Silver Sulfide ◽  
Silver Sulfide Nanoparticles

scholarly journals Site-specific ubiquitylation acts as a regulator of linker histone H1

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Eva Höllmüller ◽  
Simon Geigges ◽  
Marie L. Niedermeier ◽  
Kai-Michael Kammer ◽  
Simon M. Kienle ◽  
...  
Keyword(s):  
Posttranslational Modifications ◽  
Histone H1 ◽  
Linker Histone ◽  
Active Chromatin ◽  
Site Specific ◽  
Linker Histone H1 ◽  
Fundamental Process ◽  
Core Histones ◽  
Wide Scale

AbstractDecoding the role of histone posttranslational modifications (PTMs) is key to understand the fundamental process of epigenetic regulation. This is well studied for PTMs of core histones but not for linker histone H1 in general and its ubiquitylation in particular due to a lack of proper tools. Here, we report on the chemical synthesis of site-specifically mono-ubiquitylated H1.2 and identify its ubiquitin-dependent interactome on a proteome-wide scale. We show that site-specific ubiquitylation of H1 at position K64 modulates interactions with deubiquitylating enzymes and the deacetylase SIRT1. Moreover, it affects H1-dependent chromatosome assembly and phase separation resulting in a more open chromatosome conformation generally associated with a transcriptionally active chromatin state. In summary, we propose that site-specific ubiquitylation plays a general regulatory role for linker histone H1.

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 Studies on the role of actin's aspartic acid 3 and aspartic acid 11 using oligodeoxynucleotide-directed site-specific mutagenesis.

1988 ◽  
Vol 263 (36) ◽  
pp. 19662-19669
Author(s):  
T L Solomon ◽  
L R Solomon ◽  
L S Gay ◽  
P A Rubenstein
Keyword(s):  
Aspartic Acid ◽  
Site Specific

scholarly journals Phosphorylation of the Regulators, a Complex Facet of NF-κB Signaling in Cancer

Biomolecules ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 15
Author(s):  
Aishat Motolani ◽  
Matthew Martin ◽  
Mengyao Sun ◽  
Tao Lu
Keyword(s):  
Transcription Factor ◽  
Cardiovascular Diseases ◽  
Cancer Progression ◽  
Nuclear Factor Kappa B ◽  
Nuclear Factor ◽  
Malignant Diseases ◽  
Future Perspectives ◽  
Post Translational Modifications ◽  
Site Specific

The nuclear factor kappa B (NF-κB) is a ubiquitous transcription factor central to inflammation and various malignant diseases in humans. The regulation of NF-κB can be influenced by a myriad of post-translational modifications (PTMs), including phosphorylation, one of the most popular PTM formats in NF-κB signaling. The regulation by phosphorylation modification is not limited to NF-κB subunits, but it also encompasses the diverse regulators of NF-κB signaling. The differential site-specific phosphorylation of NF-κB itself or some NF-κB regulators can result in dysregulated NF-κB signaling, often culminating in events that induce cancer progression and other hyper NF-κB related diseases, such as inflammation, cardiovascular diseases, diabetes, as well as neurodegenerative diseases, etc. In this review, we discuss the regulatory role of phosphorylation in NF-κB signaling and the mechanisms through which they aid cancer progression. Additionally, we highlight some of the known and novel NF-κB regulators that are frequently subjected to phosphorylation. Finally, we provide some future perspectives in terms of drug development to target kinases that regulate NF-κB signaling for cancer therapeutic purposes.

The role of exudation in chronic subdural hematomas

2007 ◽  
Vol 107 (2) ◽  
pp. 290-295 ◽  
Author(s):  
Mehmet Tokmak ◽  
A. Celal Iplikcioglu ◽  
Sirzat Bek ◽  
Cem Atilla Gökduman ◽  
Mustafa Erdal
Keyword(s):  
Outer Membrane ◽  
Clinical Status ◽  
Ct Scans ◽  
Subdural Hematomas ◽  
The Mean ◽  
Grade 3 ◽  
Age Range ◽  
Exudation Rate

Object Chronic subdural hematomas (SDHs) are a local inflammatory process that causes the formation of a granulation tissue often referred to as the external or outer membrane. This membrane has abnormally permeable macrocapillaries. Therefore, exudation from the macrocapillaries in the outer membrane of chronic SDH may play an important role in the enlargement of chronic SDH. In this study the authors investigated the role of exudation in chronic SDH. Methods The authors examined 24 patients (16 men and eight women; age range 38–86 years [mean age 61.4 years]) with 27 chronic SDHs. The clinical status of the patients was evaluated according to the classification described by Markwalder. The diagnosis was established on computed tomography (CT) scans in all cases. The authors also used the Nomura Classification for judging the lesion's appearance on CT scans. Immediately after the diagnosis, all patients were administered 20 mCi (740 mBq) technetium-99m human serum albumin. Four hours later, blood and SDH samples were taken and radioactivity levels were measured in each. The ratio of activity of the samples taken from chronic SDH to the radioactivity of blood was determined as a percentage and defined as the exudation rate. On the follow-up CT scan obtained on postoperative Day 20, subdural collections thicker than 5 mm were determined to be a reaccumulation. Results The correlations between the exudation rate and age of the patients, clinical grades, CT appearances, and amount of reaccumulation were investigated. In this series the average exudation rate was 13.24% (range 2.05–28.88%). The mean exudation rates according to the clinical grades assigned to patients were as follows: Grade 0, 8.67 ± 5.64% (three patients); Grade 1, 5.07 ± 1.43% (eight patients); Grade 2, 17.87 ± 3.73% (seven patients); and Grade 3, 19.65 ± 7.67% (six patients). Exudation rates in patients with Grades 2 and 3 were significantly higher than those in Grades 0 and 1 (p < 0.05). The mean exudation rates according to the lesion's appearance on CT scans were found as follows: hypodense appearance, 6.55 ± 4.52% (eight patients); isodense appearance, 11.07 ± 6.32% (five patients); hyperdense appearance, 19.47 ± 13.61% (three patients); and mixed-density appearance, 17.40 ± 5.80% (nine patients). The differences among the groups were significant (p < 0.05). The average exudation rate was statistically higher in the patients with reaccumulation (16.30 ± 8.16%) than that in the patients without reaccumulation (9.96 ± 6.84%) (p < 0.05). Conclusions The exudation rate in chronic SDH is correlated with a higher clinical grade (Markwalder Grade 2 or 3), mixed-density CT appearance, and reaccumulation. Therefore, exudation from macrocapillaries in the outer membrane of chronic SDH probably plays an important role in the pathophysiology and the growth of chronic SDH.

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