Effect of sodium ions on conformations of the cytoplasmic loop of the PomA stator protein of Vibrio alginolyticus

2019 ◽  
Vol 166 (4) ◽  
pp. 331-341 ◽  
Author(s):  
Taira Mino ◽  
Tatsuro Nishikino ◽  
Hiroto Iwatsuki ◽  
Seiji Kojima ◽  
Michio Homma
Keyword(s):  
Conformational Change ◽  
Biological Membrane ◽  
Vibrio Alginolyticus ◽  
Sodium Ion ◽  
Deletion Mutants ◽  
Sodium Ions ◽  
Membrane Complex ◽  
Torque Generation ◽  
In Vivo Labelling

AbstractThe sodium driven flagellar stator of Vibrio alginolyticus is a hetero-hexamer membrane complex composed of PomA and PomB, and acts as a sodium ion channel. The conformational change in the cytoplasmic region of PomA for the flagellar torque generation, which interacts directly with a rotor protein, FliG, remains a mystery. In this study, we introduced cysteine mutations into cytoplasmic charged residues of PomA, which are highly conserved and interact with FliG, to detect the conformational change by the reactivity of biotin maleimide. In vivo labelling experiments of the PomA mutants revealed that the accessibility of biotin maleimide at position of E96 was reduced with sodium ions. Such a reduction was also seen in the D24N and the plug deletion mutants of PomB, and the phenomenon was independent in the presence of FliG. This sodium ions specific reduction was also detected in Escherichia coli that produced PomA and PomB from a plasmid, but not in the purified stator complex. These results demonstrated that sodium ions cause a conformational change around the E96 residue of loop2–3 in the biological membrane.

FURTHER STUDIES ON THE BINDING OF γ-AMINOBUTYRIC ACID BY BRAIN

1967 ◽  
Vol 45 (12) ◽  
pp. 1795-1807 ◽  
Author(s):  
Paula Strasberg ◽  
K. A. C. Elliott
Keyword(s):  
Rat Brain ◽  
Mitochondrial Fraction ◽  
Sodium Ion ◽  
The Other ◽  
Aminobutyric Acid ◽  
Sodium Ions ◽  
Ninhydrin Reaction ◽  
Gaba Content

Factors which can interfere with the paper chromatographic – ninhydrin method for determining γ-aminobutyric acid (GABA) are described. The GABA–ninhydrin reaction does not involve loss of CO2. GABA that is occluded in subcellular particles in plain sucrose homogenates of rat brain does not readily exchange with radioactive GABA in solution. The relevant particles are found mostly in the "mitochondrial fraction". These particles deteriorate with time and manipulations, and tend to lose much of their GABA content. The presence of sodium (but not of potassium, calcium, or magnesium) in the suspending medium allows considerably more GABA to be bound. The extra bound GABA is exchangeable with free labelled GABA. Sodium also promotes some exchange between free and occluded GABA. It is concluded from the present and previous results that in brain in vivo very little GABA exists in a freely diffusing situation. There are two forms of bound GABA. One of these is an occluded or storage form which does not readily exchange with free GABA though exchange is to some extent promoted by sodium ions. The other is a form which occurs only in the presence of sodium ion and is freely exchangeable with GABA in solution.

scholarly journals Stu2p binds tubulin and undergoes an open-to-closed conformational change

2006 ◽  
Vol 172 (7) ◽  
pp. 1009-1022 ◽  
Author(s):  
Jawdat Al-Bassam ◽  
Mark van Breugel ◽  
Stephen C. Harrison ◽  
Anthony Hyman
Keyword(s):  
Conformational Change ◽  
Conformational Transition ◽  
Budding Yeast ◽  
Microtubule Dynamics ◽  
Open Structure ◽  
Microtubule Associated Proteins ◽  
Associated Proteins ◽  
The Common

Stu2p from budding yeast belongs to the conserved Dis1/XMAP215 family of microtubule-associated proteins (MAPs). The common feature of proteins in this family is the presence of HEAT repeat–containing TOG domains near the NH2 terminus. We have investigated the functions of the two TOG domains of Stu2p in vivo and in vitro. Our data suggest that Stu2p regulates microtubule dynamics through two separate activities. First, Stu2p binds to a single free tubulin heterodimer through its first TOG domain. A large conformational transition in homodimeric Stu2p from an open structure to a closed one accompanies the capture of a single free tubulin heterodimer. Second, Stu2p has the capacity to associate directly with microtubule ends, at least in part, through its second TOG domain. These two properties lead to the stabilization of microtubules in vivo, perhaps by the loading of tubulin dimers at microtubule ends. We suggest that this mechanism of microtubule regulation is a conserved feature of the Dis1/XMAP215 family of MAPs.

scholarly journals Synthesis and Evaluation of Novel α-Aminoamides Containing Benzoheterocyclic Moiety for the Treatment of Pain

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1716
Author(s):  
Kun Tong ◽  
Ruotian Zhang ◽  
Fengzhi Ren ◽  
Tao Zhang ◽  
Junlin He ◽  
...  
Keyword(s):  
Ion Channels ◽  
Patch Clamp ◽  
Formalin Test ◽  
Sodium Ion ◽  
Inhibitory Potency ◽  
Voltage Gated ◽  
Patch Clamp Electrophysiology ◽  
Sodium Ion Channels

Novel α-aminoamide derivatives containing different benzoheterocyclics moiety were synthesized and evaluated as voltage-gated sodium ion channels blocks the treatment of pain. Compounds 6a, 6e, and 6f containing the benzofuran group displayed more potent in vivo analgesic activity than ralfinamide in both the formalin test and the writhing assay. Interestingly, they also exhibited potent in vitro anti-Nav1.7 and anti-Nav1.8 activity in the patch-clamp electrophysiology assay. Therefore, compounds 6a, 6e, and 6f, which have inhibitory potency for two pain-related Nav targets, could serve as new leads for the development of analgesic medicines.

scholarly journals Absorption of lactulose from mammalian gastrointestinal tract

1979 ◽  
Vol 41 (1) ◽  
pp. 47-51 ◽  
Author(s):  
D. F. Evered ◽  
F. Sadoogh-Abasian
Keyword(s):  
Small Intestine ◽  
Calcium Ions ◽  
Clinical Evidence ◽  
Buccal Cavity ◽  
Rat Small Intestine ◽  
Sodium Ions ◽  
Mode Of Transport ◽  
Poor Absorption

1. The disaccharide lactulose (galactosyl-β-1,4-fructose) was poorly absorbed from rat small intestine in vitro and human mouth in vivo.2. These results confirm indirect clinical evidence of poor absorption from the intestine.3. The presence of calcium ions, or absence of sodium ions, had no effect on lactulose absorption from the buccal cavity.4. The presence of ouabain, or absence of Na+, did not decrease the absorption of lactulose from small intestine.5. It is thought that the mode of transport, in both instances, is by passive diffusion with the concentration gradient.

Effects of truncated neurofilament proteins on the endogenous intermediate filaments in transfected fibroblasts

1991 ◽  
Vol 99 (2) ◽  
pp. 335-350 ◽  
Author(s):  
S.S. Chin ◽  
P. Macioce ◽  
R.K. Liem
Keyword(s):  
Intermediate Filament ◽  
Dominant Negative ◽  
Deletion Mutants ◽  
Tail Domain ◽  
Cultured Fibroblasts ◽  
Mutant Proteins ◽  
Amino Terminal ◽  
Novel Approach ◽  
Carboxyl Terminal

The expression and assembly characteristics of carboxyl- and amino-terminal deletion mutants of rat neurofilament low Mr (NF-L) and neurofilament middle Mr (NF-M) proteins were examined by transient transfection of cultured fibroblasts. Deletion of the carboxyl-terminal tail domain of either protein indicated that this region was not absolutely essential for co-assembly into the endogenous vimentin cytoskeleton. However, deletion into the alpha-helical rod domain resulted in an inability of the mutant proteins to co-assemble with vimentin into filamentous structures. Instead, the mutant proteins appeared to be assembled into unusual tubular-vesicular structures. Additionally, these latter deletions appeared to act as dominant negative mutants which induced the collapse of the endogenous vimentin cytoskeleton as well as the constitutively expressed NF-H and NF-M cytoskeletons in stably transfected cell lines. Thus, an intact alpha-helical rod domain was essential for normal IF co-assembly whereas carboxyl-terminal deletions into this region resulted in dramatic alterations of the existing type III and IV intermediate filament cytoskeletons in vivo. Deletions from the amino-terminal end into the alpha-helical rod region gave different results. With these deletions, the transfected protein was not co-assembled into filaments and the endogenous vimentin IF network was not disrupted, indicating that these deletion mutants are recessive. The dominant negative mutants may provide a novel approach to studying intermediate filament function within living cells.

Transient expression of a mouse alpha-fetoprotein minigene: deletion analyses of promoter function

1983 ◽  
Vol 3 (7) ◽  
pp. 1295-1309
Author(s):  
R W Scott ◽  
S M Tilghman
Keyword(s):  
Transient Expression ◽  
Hela Cells ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Alpha Fetoprotein ◽  
Tata Box ◽  
Deletion Mutants ◽  
Promoter Function ◽  
Flanking Region

The constitutive transcription of a mouse alpha-fetoprotein (AFP) minigene was examined during the transient expression of AFP-simian virus 40-pBR322 recombinant DNAs introduced into HeLa cells by Ca3(PO4)2 precipitation. We tested three constructs, each of which contains the AFP minigene and pBR322 DNAs inserted in the late region of simian virus 40 and found that the relative efficiency of AFP gene expression was dependent on the arrangement of the three DNA elements in the vector. The transcripts begin at the authentic AFP cap site and are properly spliced and polyadenylated. To define a sequence domain in the 5' flanking region of the AFP gene required for constitutive expression, sequential 5' deletion mutants of the AFP minigene were constructed and introduced into HeLa cells. All AFP deletion mutants which retained at least the TATA motif located 30 base pairs upstream from the cap site were capable of directing accurate and efficient AFP transcription. However, when the TATA sequence was deleted, no accurately initiated AFP transcripts were detected. These results are identical to those obtained from in vitro transcription of truncated AFP 5' deletion mutant templates assayed in HeLa cell extracts. The rate of AFP transcription in vivo was unaffected by deletion of DNA upstream of the AFP TATA box but was greatly affected by the distance between the simian virus 40 control region and the 5' end of the gene. The absence of any promoter activity upstream of the TATA box in this assay system is in contrast to what has been reported for several other eucaryotic structural genes in a variety of in vivo systems. A sequence comparison between the 5' flanking region of the AFP gene and these genes suggested that the AFP gene lacks those structural elements found to be important for constitutive transcription in vivo. Either the AFP gene lacks upstream promoter function in the 5' flanking DNA contained within the minigene, or the use of a viral vector in a heterologous system precludes its identification.

The Effect of Enzymatic Depolymerization of Arterial Mucopolysaccharides on Sodium Ion Content and Vessel Reactivity

1971 ◽  
Vol 40 (4) ◽  
pp. 293-303 ◽  
Author(s):  
G. S. Harris ◽  
W. A. Palmer
Keyword(s):  
Cation Binding ◽  
Sodium Ion ◽  
Sodium Ions ◽  
High Concentration ◽  
Ion Content ◽  
Binding Properties ◽  
Arterial Walls ◽  
Testicular Hyaluronidase ◽  
Enzymatic Depolymerization

1. The presence of mucopolysaccharides within arterial walls may be associated with the high concentration of sodium ions within this tissue. These polyanions are sensitive to enzymatic depolymerization which results in a loss of the cation binding properties of the molecule. 2. In this study testicular hyaluronidase perfused through isolated arterial segments resulted in a decrease in reactivity of the artery to 65% that of control arteries. Associated with this finding was a 33% decrease in the sodium ion content of the stimulated hyaluronidase-treated artery. When a variety of other sympathetically innervated tissues were treated with hyaluronidase there was no decrease in reactivity or sodium ion content.

DNA KNOT FORMATION IN AQUEOUS SOLUTIONS

1994 ◽  
Vol 03 (03) ◽  
pp. 287-298 ◽  
Author(s):  
STANLEY Y. SHAW ◽  
JAMES C. WANG
Keyword(s):  
Aqueous Solutions ◽  
Experimental Test ◽  
Attractive Potential ◽  
Sodium Ions ◽  
Magnesium Ions ◽  
Close Apposition ◽  
Closed Chain ◽  
Solvent Properties

The knotting probability of a closed chain has been calculated as a function of chain dimensions and solvent properties in a number of studies. We have measured the probability of DNA knot formation upon random cyclization of linear DNA in vitro to provide an experimental test of the various theoretical treatments of the problem; parameters of these models, such as the effective chain diameter of DNA, were calculated in different concentrations of counterions. Our results in the presence of sodium ions agree well with theoretical treatments of DNA as a polyelectrolyte; knotting data in the presence of divalent magnesium ions indicate that moderate concentrations of magnesium ions can induce an attractive potential between DNA segments, resulting in negative values of the calculated effective DNA helix diameter. We discuss structures in which the divalent magnesium counterion facilitates the close apposition of two DNA segments, and review the effect of chemical- and protein-mediated crosslinks between DNA segments on DNA knot formation. Finally, we consider DNA knot formation in vivo.

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