scholarly journals Inhibitors of a Na+-pumping NADH-ubiquinone oxidoreductase play multiple roles to block enzyme function

2020 ◽  
Vol 295 (36) ◽  
pp. 12739-12754
Author(s):  
Takahiro Masuya ◽  
Yuki Sano ◽  
Hinako Tanaka ◽  
Nicole L. Butler ◽  
Takeshi Ito ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Interfacial Area ◽  
Multiple Roles ◽  
Competitive Behavior ◽  
Design Strategies ◽  
Ubiquinone Oxidoreductase ◽  
Nadh Ubiquinone Oxidoreductase ◽  
Group 2 ◽  
And Function ◽  
Derivatives Of

The Na+-pumping NADH-ubiquinone (UQ) oxidoreductase (Na+-NQR) is present in the respiratory chain of many pathogenic bacteria and is thought to be a promising antibiotic target. Whereas many details of Na+-NQR structure and function are known, the mechanisms of action of potent inhibitors is not well-understood; elucidating the mechanisms would not only advance drug design strategies but might also provide insights on a terminal electron transfer from riboflavin to UQ. To this end, we performed photoaffinity labeling experiments using photoreactive derivatives of two known inhibitors, aurachin and korormicin, on isolated Vibrio cholerae Na+-NQR. The inhibitors labeled the cytoplasmic surface domain of the NqrB subunit including a protruding N-terminal stretch, which may be critical to regulate the UQ reaction in the adjacent NqrA subunit. The labeling was blocked by short-chain UQs such as ubiquinone-2. The photolabile group (2-aryl-5-carboxytetrazole (ACT)) of these inhibitors reacts with nucleophilic amino acids, so we tested mutations of nucleophilic residues in the labeled region of NqrB, such as Asp49 and Asp52 (to Ala), and observed moderate decreases in labeling yields, suggesting that these residues are involved in the interaction with ACT. We conclude that the inhibitors interfere with the UQ reaction in two ways: the first is blocking structural rearrangements at the cytoplasmic interface between NqrA and NqrB, and the second is the direct obstruction of UQ binding at this interfacial area. Unusual competitive behavior between the photoreactive inhibitors and various competitors corroborates our previous proposition that there may be two inhibitor binding sites in Na+-NQR.

Mechanisms of sodium transport in bacteria

1990 ◽  
Vol 326 (1236) ◽  
pp. 465-477 ◽  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Atp Synthesis ◽  
Oxaloacetate Decarboxylase ◽  
Synthesis Mechanism ◽  
Physiological Importance ◽  
Ubiquinone Oxidoreductase ◽  
Nadh Ubiquinone Oxidoreductase ◽  
Ion Gradient ◽  
Propionigenium Modestum ◽  
And Function

In some bacteria, an Na + circuit is an important link between exergonic and endergonic membrane reactions. The physiological importance of Na + ion cycling is described in detail for three different bacteria. Klebsiella pneumoniae fermenting citrate pumps Na + outwards by oxaloacetate decarboxylase and uses the Na + ion gradient thus established for citrate uptake. Another possible function of the Na + gradient may be to drive the endergonic reduction of NAD + with ubiquinol as electron donor. In Vibrio alginolyticus , an Na + gradient is established by the NADH: ubiquinone oxidoreductase segment of the respiratory chain; the Na + gradient drives solute uptake, flagellar motion and possibly ATP synthesis. In Propionigenium modestum , ATP biosynthesis is entirely dependent on the Na + ion gradient established upon decarboxylation of methylmalonyl-CoA. The three Na + -translocating enzymes, oxaloacetate decarboxylase of Klebsiella pneumoniae , NADH: ubiquinone oxidoreductase of Vibrio alginolyticus and ATPase ( F 1 F 0 ) of Propionigenium modestum have been isolated and studied with respect to structure and function. Oxaloacetate decarboxylase consists of a peripheral subunit (α), that catalyses the carboxyl transfer from oxaloacetate to enzyme-bound biotin. The subunits β and γ are firmly embedded in the membrane and catalyse the decarboxylation of the carboxybiotin enzyme, coupled to Na + transport. A two-step mechanism has also been demonstrated for the respiratory Na + pump. Semiquinone radicals are first formed with the electrons from NADH; subsequently, these radicals dismutate in an Na + -dependent reaction to quinone and quinol. The ATPase of P. modestum is closely related in its structure to the F 1 F 0 ATPase of E. coli , but uses Na + as the coupling ion. A specific role of protons in the ATP synthesis mechanism is therefore excluded.

scholarly journals Targeting Pin1 for Modulation of Cell Motility and Cancer Therapy

Biomedicines ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 359
Author(s):  
Hsiang-Hao Chuang ◽  
Yen-Yi Zhen ◽  
Yu-Chen Tsai ◽  
Cheng-Hao Chuang ◽  
Ming-Shyan Huang ◽  
...  
Keyword(s):  
Cancer Therapy ◽  
Tumor Suppressors ◽  
Protein Conformation ◽  
Genome Stability ◽  
Recent Progress ◽  
Multiple Roles ◽  
Cancer Development ◽  
Cancer Hallmarks ◽  
Underlying Mechanisms ◽  
And Function

Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1) specifically binds and isomerizes the phosphorylated serine/threonine-proline (pSer/Thr-Pro) motif, which leads to changes in protein conformation and function. Pin1 is widely overexpressed in cancers and plays an important role in tumorigenesis. Mounting evidence has revealed that targeting Pin1 is a potential therapeutic approach for various cancers by inhibiting cell proliferation, reducing metastasis, and maintaining genome stability. In this review, we summarize the underlying mechanisms of Pin1-mediated upregulation of oncogenes and downregulation of tumor suppressors in cancer development. Furthermore, we also discuss the multiple roles of Pin1 in cancer hallmarks and examine Pin1 as a desirable pharmaceutical target for cancer therapy. We also summarize the recent progress of Pin1-targeted small-molecule compounds for anticancer activity.

scholarly journals Islands of complex DNA are widespread in Drosophila centric heterochromatin.

Genetics ◽  
1995 ◽  
Vol 141 (1) ◽  
pp. 283-303
Author(s):  
M H Le ◽  
D Duricka ◽  
G H Karpen
Keyword(s):  
Dna Sequences ◽  
Structure And Function ◽  
Southern Analysis ◽  
Cloning And Sequencing ◽  
Pulsed Field ◽  
Drosophila Heterochromatin ◽  
And Function ◽  
Heterochromatin Structure ◽  
Derivatives Of ◽  
Eukaryotic Genomes

Abstract Heterochromatin is a ubiquitous yet poorly understood component of multicellular eukaryotic genomes. Major gaps exist in our knowledge of the nature and overall organization of DNA sequences present in heterochromatin. We have investigated the molecular structure of the 1 Mb of centric heterochromatin in the Drosophila minichromosome Dp1187. A genetic screen of irradiated minichromosomes yielded rearranged derivatives of Dp1187 whose structures were determined by pulsed-field Southern analysis and PCR. Three Dp1187 deletion derivatives and an inversion had one breakpoint in the euchromatin and one in the heterochromatin, providing direct molecular access to previously inaccessible parts of the heterochromatin. End-probed pulsed-field restriction mapping revealed the presence of at least three "islands" of complex DNA, Tahiti, Moorea, and Bora Bora, constituting approximately one half of the Dp1187 heterochromatin. Pulsed-field Southern analysis demonstrated that Drosophila heterochromatin in general is composed of alternating blocks of complex DNA and simple satellite DNA. Cloning and sequencing of a small part of one island, Tahiti, demonstrated the presence of a retroposon. The implications of these findings to heterochromatin structure and function are discussed.

scholarly journals Transcription Factors in the Development and Function of Group 2 Innate Lymphoid Cells

2019 ◽  
Vol 20 (6) ◽  
pp. 1377 ◽  
Author(s):  
Takashi Ebihara ◽  
Ichiro Taniuchi
Keyword(s):  
Transcription Factors ◽  
Physiological State ◽  
Allergic Inflammation ◽  
Allergic Diseases ◽  
Innate Lymphoid Cells ◽  
Lymphoid Cells ◽  
Th2 Cytokine ◽  
Parasitic Worm ◽  
Group 2 ◽  
And Function

Group 2 innate lymphoid cells (ILC2s) are tissue-resident cells and are a major source of innate TH2 cytokine secretion upon allergen exposure or parasitic-worm infection. Accumulating studies have revealed that transcription factors, including GATA-3, Bcl11b, Gfi1, RORα, and Ets-1, play a role in ILC2 differentiation. Recent reports have further revealed that the characteristics and functions of ILC2 are influenced by the physiological state of the tissues. Specifically, the type of inflammation strongly affects the ILC2 phenotype in tissues. Inhibitory ILC2s, memory-like ILC2s, and ex-ILC2s with ILC1 features acquire their characteristic properties following exposure to their specific inflammatory environment. We have recently reported a new ILC2 population, designated as exhausted-like ILC2s, which emerges after a severe allergic inflammation. Exhausted-like ILC2s are featured with low reactivity and high expression of inhibitory receptors. Therefore, for a more comprehensive understanding of ILC2 function and differentiation, we review the recent knowledge of transcriptional regulation of ILC2 differentiation and discuss the roles of the Runx transcription factor in controlling the emergence of exhausted-like ILC2s. The concept of exhausted-like ILC2s sheds a light on a new aspect of ILC2 biology in allergic diseases.

Effects of avertin versus xylazine-ketamine anesthesia on cardiac function in normal mice

2001 ◽  
Vol 281 (5) ◽  
pp. H1938-H1945 ◽  
Author(s):  
Chari Y. T. Hart ◽  
John C. Burnett ◽  
Margaret M. Redfield
Keyword(s):  
Cardiac Function ◽  
Diastolic Pressure ◽  
Systolic Function ◽  
Pressure Rise ◽  
Left Ventricular ◽  
Lv Function ◽  
Ketamine Anesthesia ◽  
The Difference ◽  
And Function ◽  
Derivatives Of

Anesthetic regimens commonly administered during studies that assess cardiac structure and function in mice are xylazine-ketamine (XK) and avertin (AV). While it is known that XK anesthesia produces more bradycardia in the mouse, the effects of XK and AV on cardiac function have not been compared. We anesthetized normal adult male Swiss Webster mice with XK or AV. Transthoracic echocardiography and closed-chest cardiac catheterization were performed to assess heart rate (HR), left ventricular (LV) dimensions at end diastole and end systole (LVDd and LVDs, respectively), fractional shortening (FS), LV end-diastolic pressure (LVEDP), the time constant of isovolumic relaxation (τ), and the first derivatives of LV pressure rise and fall (dP/d t max and dP/d t min, respectively). During echocardiography, HR was lower in XK than AV mice (250 ± 14 beats/min in XK vs. 453 ± 24 beats/min in AV, P < 0.05). Preload was increased in XK mice (LVDd: 4.1 ± 0.08 mm in XK vs. 3.8 ± 0.09 mm in AV, P < 0.05). FS, a load-dependent index of systolic function, was increased in XK mice (45 ± 1.2% in XK vs. 40 ± 0.8% in AV, P < 0.05). At LV catheterization, the difference in HR with AV (453 ± 24 beats/min) and XK (342 ± 30 beats/min, P < 0.05) anesthesia was more variable, and no significant differences in systolic or diastolic function were seen in the group as a whole. However, in XK mice with HR <300 beats/min, LVEDP was increased (28 ± 5 vs. 6.2 ± 2 mmHg in mice with HR >300 beats/min, P < 0.05), whereas systolic (LV dP/d t max: 4,402 ± 798 vs. 8,250 ± 415 mmHg/s in mice with HR >300 beats/min, P < 0.05) and diastolic (τ: 23 ± 2 vs. 14 ± 1 ms in mice with HR >300 beats/min, P < 0.05) function were impaired. Compared with AV, XK produces profound bradycardia with effects on loading conditions and ventricular function. The disparate findings at echocardiography and LV catheterization underscore the importance of comprehensive assessment of LV function in the mouse.

scholarly journals Alkaloid-Rich Crude Extracts, Fractions and Piperamide Alkaloids of Piper guineense Possess Promising Antibacterial Effects

Antibiotics ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 98 ◽  
Author(s):  
Eunice Mgbeahuruike ◽  
Pia Fyhrquist ◽  
Heikki Vuorela ◽  
Riitta Julkunen-Tiitto ◽  
Yvonne Holm
Keyword(s):  
Antibacterial Activity ◽  
Pathogenic Bacteria ◽  
Bacterial Resistance ◽  
Hot Water ◽  
Bacterial Strains ◽  
Inhibitory Effects ◽  
Piper Guineense ◽  
E Coli ◽  
Growth Inhibitory ◽  
Derivatives Of

Piper guineense is a food and medicinal plant commonly used to treat infectious diseases in West-African traditional medicine. In a bid to identify new antibacterial compounds due to bacterial resistance to antibiotics, twelve extracts of P. guineense fruits and leaves, obtained by sequential extraction, as well as the piperine and piperlongumine commercial compounds were evaluated for antibacterial activity against human pathogenic bacteria. HPLC-DAD and UHPLC/Q-TOF MS analysis were conducted to characterize and identify the compounds present in the extracts with promising antibacterial activity. The extracts, with the exception of the hot water decoctions and macerations, contained piperamide alkaloids as their main constituents. Piperine, dihydropiperine, piperylin, dihydropiperylin or piperlonguminine, dihydropiperlonguminine, wisanine, dihydrowisanine and derivatives of piperine and piperidine were identified in a hexane extract of the leaf. In addition, some new piperamide alkaloids were identified, such as a piperine and a piperidine alkaloid derivative and two unknown piperamide alkaloids. To the best of our knowledge, there are no piperamides reported in the literature with similar UVλ absorption maxima and masses. A piperamide alkaloid-rich hexane leaf extract recorded the lowest MIC of 19 µg/mL against Sarcina sp. and gave promising growth inhibitory effects against S. aureus and E. aerogenes as well, inhibiting the growth of both bacteria with a MIC of 78 µg/mL. Moreover, this is the first report of the antibacterial activity of P. guineense extracts against Sarcina sp. and E. aerogenes. Marked growth inhibition was also obtained for chloroform extracts of the leaves and fruits against P. aeruginosa with a MIC value of 78 µg/mL. Piperine and piperlongumine were active against E. aerogenes, S. aureus, E. coli, S. enterica, P. mirabilis and B. cereus with MIC values ranging from 39–1250 µg/mL. Notably, the water extracts, which were almost devoid of piperamide alkaloids, were not active against the bacterial strains. Our results demonstrate that P. guineense contains antibacterial alkaloids that could be relevant for the discovery of new natural antibiotics.

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