Isolation of polypeptides with microtubule-translocating activity from phragmoplasts of tobacco BY-2 cells

1994 ◽  
Vol 107 (8) ◽  
pp. 2249-2257 ◽  
Author(s):  
T. Asada ◽  
H. Shibaoka
Keyword(s):  
Motor Activity ◽  
Molecular Basis ◽  
Plant Cells ◽  
Cell Plate ◽  
Gtpase Activity ◽  
High Concentration ◽  
Higher Plant ◽  
Main Components ◽  
Brain Tubulin

As part of our efforts to understand the molecular basis of the microtubule-associated motility that is involved in cytokinesis in higher plant cells, an attempt was made to identify proteins with the ability to translocate microtubules in an extract from isolated phragmoplasts. Homogenization of isolated phragmoplasts in a solution that contained MgATP, MgGTP and a high concentration of NaCl resulted in the release from phragmoplasts of factors with ATPase and GTPase activity that were stimulated by microtubules. A protein fraction with microtubule-dependent ATPase and GTPase activity caused minus-end-headed gliding of microtubules in the presence of ATP or GTP. Polypeptides with microtubule-translocating activity cosedimented with microtubules that had been assembled in vitro from brain tubulin and were dissociated from sedimented microtubules by addition of ATP or GTP. After cosedimentation and dissociation procedures, a 125 kDa polypeptide and a 120 kDa polypeptide were recovered in a fraction that supported minus-end-headed gliding of microtubules. The rate of microtubule gliding that was caused by the fraction that contained the 125 kDa and 120 kDa polypeptides as main components was 1.28 microns/minute in the presence of ATP and 0.50 microns/minute in the presence of GTP. This fraction contained some microtubule-associated polypeptides in addition to the 125 kDa and 120 kDa polypeptides, but a fraction that contained only these additional polypeptides did not cause any translocation of microtubules. Thus, it appeared that the 125 kDa and 120 kDa polypeptides were responsible for translocation of microtubules. These polypeptides with plus-end-directed motor activity may play an important role in formation of the cell plate and in the organization of the phragmoplast.

Identification and preliminary characterization of a 65 kDa higher-plant microtubule-associated protein

1993 ◽  
Vol 105 (4) ◽  
pp. 891-901 ◽  
Author(s):  
J. Chang-Jie ◽  
S. Sonobe
Keyword(s):  
Polyclonal Antibodies ◽  
Cold Treatment ◽  
Plant Cells ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
High Concentration ◽  
Animal Cells ◽  
Higher Plant ◽  
Microtubule Protein

Microtubules in plant cells, as in animal cells, are dynamic structures. However, our lack of knowledge about the constituents of microtubules in plant cells has prevented us from understanding the mechanisms that control microtubule dynamics. To characterize some of these constituents, a cytoplasmic extract was prepared from evacuolated protoplasts (miniprotoplasts) of tobacco BY-2 cells, and microtubules were assembled in the presence of taxol and disassembled by cold treatment in the presence of Ca2+ and a high concentration of NaCl. SDS-PAGE analysis of triple-cycled microtubule protein revealed the presence of 120 kDa, 110 kDa and a group of 60–65 kDa polypeptides in addition to tubulin. Since these polypeptides had copolymerized with tubulin, through the three cycles of assembly and disassembly, and they bundle microtubules, we tentatively identified the three polypeptides as microtubule-associated proteins (MAPs). To characterize these factors further, triple-cycled microtubule protein was fractionated by Mono-Q anion-exchange chromatography and the microtubule-bundling activity of each fraction was examined. Fractions having microtubule-bundling activity contained only the 65 kDa MAP, an indication that the 65 kDa MAP is responsible for the bundling of microtubules. Purified 65 kDa MAP formed cross-bridge structures between adjacent microtubules in vitro. Polyclonal antibodies were raised in mice against the 65 kDa MAP. Immunofluorescence microscopy revealed that the 65 kDa MAP colocalized with microtubules in BY-2 cells throughout the cell cycle. Western blotting analysis of extracts from several species of plants suggested that the 65 kDa MAP and/or related peptides are widely distributed in the plant kingdom.

scholarly journals Effect of 2″-O-Rhamnosyl Icariside II, Baohuoside I and Baohuoside II in Herba Epimedii on Cytotoxicity Indices in HL-7702 and HepG2 Cells

Molecules ◽  
2019 ◽  
Vol 24 (7) ◽  
pp. 1263 ◽  
Author(s):  
Lin Zhang ◽  
Ting Wang ◽  
Bao-Sheng Zhao ◽  
Jing-Xuan Zhang ◽  
Song Yang ◽  
...  
Keyword(s):  
Hepg2 Cells ◽  
In Vitro Models ◽  
The Other ◽  
High Concentration ◽  
Clinical Safety ◽  
Herba Epimedii ◽  
Icariside Ii ◽  
Toxic Mechanisms ◽  
Main Components

Herba Epimedii, a commonly used Chinese medicine, has attracted much attention recently because of its potential hepatotoxic effects. 2″-O-Rhamnosyl icariside II, baohuoside I and baohuoside II are the main components of Herba Epimedii, and previous research indicates that these three compounds are related to the hepatotoxicity of Herba Epimedii. To test this idea, in this study, HL-7702 and HepG2 cells were chosen as the in vitro models and the influences of these three compounds on a series of cytotoxicity indices, including ALT, AST, LDH, SOD, GSH, MDA, ROS and MMP, were determined. The results showed that at certain concentrations, the three compounds had different effects on the indices. Among them, baohuoside I at high concentration (32 μg/mL) displayed more significant cytotoxicity than the other two compounds; therefore, it was inferred to be more closely correlated with the liver injury induced by Herba Epimedii combined with the previous study, and its toxic mechanisms may be involved in increasing oxidative stress and inducing apoptosis. The findings of this study may provide evidence of the toxic composition of Herba Epimedii to preliminarily discuss the toxic mechanisms and provide improved guidance for its clinical safety.

Stable incorporation of plasmid DNA into higher plant cells: the molecular basis of crown gall tumorigenesis

Cell ◽  
1977 ◽  
Vol 11 (2) ◽  
pp. 263-271 ◽  
Author(s):  
Mary-Dell Chilton ◽  
Martin H. Drummond ◽  
Donald J. Merlo ◽  
Daniela Sciaky ◽  
Alice L. Montoya ◽  
...  
Keyword(s):  
Plasmid Dna ◽  
Crown Gall ◽  
Molecular Basis ◽  
Plant Cells ◽  
Higher Plant ◽  
Stable Incorporation

scholarly journals Myosin VIII associates with microtubule ends and together with actin plays a role in guiding plant cell division

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Shu-Zon Wu ◽  
Magdalena Bezanilla
Keyword(s):  
Cell Division ◽  
Motor Activity ◽  
Molecular Mechanism ◽  
Plant Cell ◽  
Actin Filaments ◽  
Plant Cells ◽  
Cell Plate ◽  
Cell Periphery ◽  
Division Site ◽  
Plant Cell Division

Plant cells divide using the phragmoplast, a microtubule-based structure that directs vesicles secretion to the nascent cell plate. The phragmoplast forms at the cell center and expands to reach a specified site at the cell periphery, tens or hundreds of microns distant. The mechanism responsible for guiding the phragmoplast remains largely unknown. Here, using both moss and tobacco, we show that myosin VIII associates with the ends of phragmoplast microtubules and together with actin plays a role in guiding phragmoplast expansion to the cortical division site. Our data lead to a model whereby myosin VIII links phragmoplast microtubules to the cortical division site via actin filaments. Myosin VIII's motor activity along actin provides a molecular mechanism for steering phragmoplast expansion.

Maytansine-Induced Mitotic Arrest in Human Lymphoblasts

1977 ◽  
Vol 35 ◽  
pp. 460-461
Author(s):  
Tai-Te Chao ◽  
John Sullivan ◽  
Awtar Krishan
Keyword(s):  
Electron Microscopy ◽  
Cell Cycle ◽  
Transmission Electron Microscopy ◽  
Tubulin Polymerization ◽  
Vinca Alkaloids ◽  
Antimitotic Activity ◽  
Transmission Electron ◽  
Flow Microfluorometry ◽  
Brain Tubulin

Maytansine, a novel ansa macrolide (1), has potent anti-tumor and antimitotic activity (2, 3). It blocks cell cycle traverse in mitosis with resultant accumulation of metaphase cells (4). Inhibition of brain tubulin polymerization in vitro by maytansine has also been reported (3). The C-mitotic effect of this drug is similar to that of the well known Vinca- alkaloids, vinblastine and vincristine. This study was carried out to examine the effects of maytansine on the cell cycle traverse and the fine struc- I ture of human lymphoblasts.Log-phase cultures of CCRF-CEM human lymphoblasts were exposed to maytansine concentrations from 10-6 M to 10-10 M for 18 hrs. Aliquots of cells were removed for cell cycle analysis by flow microfluorometry (FMF) (5) and also processed for transmission electron microscopy (TEM). FMF analysis of cells treated with 10-8 M maytansine showed a reduction in the number of G1 cells and a corresponding build-up of cells with G2/M DNA content.

Confocal microscopy of the cytoskeleton in living plant cells following microinjection of fluorescent probes

1993 ◽  
Vol 51 ◽  
pp. 130-131
Author(s):  
Ann Cleary
Keyword(s):  
Cell Division ◽  
Fluorescent Probes ◽  
Actin Filaments ◽  
Intracellular Transport ◽  
Cell Structure ◽  
Plant Cells ◽  
Cell Plate ◽  
Cell Cortex ◽  
Living Plant ◽  
Rhodamine Phalloidin

Microinjection of fluorescent probes into living plant cells reveals new aspects of cell structure and function. Microtubules and actin filaments are dynamic components of the cytoskeleton and are involved in cell growth, division and intracellular transport. To date, cytoskeletal probes used in microinjection studies have included rhodamine-phalloidin for labelling actin filaments and fluorescently labelled animal tubulin for incorporation into microtubules. From a recent study of Tradescantia stamen hair cells it appears that actin may have a role in defining the plane of cell division. Unlike microtubules, actin is present in the cell cortex and delimits the division site throughout mitosis. Herein, I shall describe actin, its arrangement and putative role in cell plate placement, in another material, living cells of Tradescantia leaf epidermis.The epidermis is peeled from the abaxial surface of young leaves usually without disruption to cytoplasmic streaming or cell division. The peel is stuck to the base of a well slide using 0.1% polyethylenimine and bathed in a solution of 1% mannitol +/− 1 mM probenecid.

Molecular Basis of Iterative C–H Oxidation by TamI, a Multifunctional P450 Monooxygenase from the Tirandamycin Biosynthetic Pathway

2020 ◽  
Author(s):  
Sean A. Newmister ◽  
Kinshuk Raj Srivastava ◽  
Rosa V. Espinoza ◽  
Kersti Caddell Haatveit ◽  
Yogan Khatri ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Molecular Basis ◽  
Hydrophobic Interactions ◽  
Cytochromes P450 ◽  
Targeted Mutagenesis ◽  
P450 Monooxygenase ◽  
Bond Functionalization ◽  
Dynamics Simulations

Biocatalysis offers an expanding and powerful strategy to construct and diversify complex molecules by C-H bond functionalization. Due to their high selectivity, enzymes have become an essential tool for C-H bond functionalization and offer complementary reactivity to small-molecule catalysts. Hemoproteins, particularly cytochromes P450, have proven effective for selective oxidation of unactivated C-H bonds. Previously, we reported the in vitro characterization of an oxidative tailoring cascade in which TamI, a multifunctional P450 functions co-dependently with the TamL flavoprotein to catalyze regio- and stereoselective hydroxylations and epoxidation to yield tirandamycin A and tirandamycin B. TamI follows a defined order including 1) C10 hydroxylation, 2) C11/C12 epoxidation, and 3) C18 hydroxylation. Here we present a structural, biochemical, and computational investigation of TamI to understand the molecular basis of its substrate binding, diverse reactivity, and specific reaction sequence. The crystal structure of TamI in complex with tirandamycin C together with molecular dynamics simulations and targeted mutagenesis suggest that hydrophobic interactions with the polyene chain of its natural substrate are critical for molecular recognition. QM/MM calculations and molecular dynamics simulations of TamI with variant substrates provided detailed information on the molecular basis of sequential reactivity, and pattern of regio- and stereo-selectivity in catalyzing the three-step oxidative cascade.<br>

ASSOCIATION OF BDKRB2 AND ACE GENE POLYMORPHISM WITH ERYTHROCYTE ADRENOREACTIVITY IN YOUNG MEN WITH DIFFERENT MOTOR ACTIVITY

2020 ◽  
pp. 96-107
Author(s):  
A.Z. Dautova ◽  
E.A. Khazhieva ◽  
V.G. Shamratova ◽  
L.Z. Sadykova
Keyword(s):  
Gene Polymorphism ◽  
Angiotensin Converting Enzyme ◽  
Motor Activity ◽  
Receptor Gene ◽  
Young Men ◽  
Converting Enzyme ◽  
Ace Gene ◽  
Ace Gene Polymorphism ◽  
Physically Inactive

The aim of the paper was to study the association of polymorphic variants of rs4646994 (I/D) of the angiotensin converting enzyme gene (ACE) and rs5810761 (+9/-9) of the bradykinin B2 receptor gene (BDKRB2) with erythrocyte adrenoreactivity (ARE) in athletes and untrained young men. Materials and Methods. The study involved 61 young men (aged 21–23) with different levels of motor activity (MA). ARE was evaluated according to the erythrocyte sedimentation rate (ESR) change under adrenaline in vitro at final concentrations 10-5, 10-6, 10-7, 10-9, 10-11, 10-13 g/ml of venous blood. According to the effect observed and ESR shifts under adrenaline, we distinguished 3 ARE types: antiaggregative (AnAg), areactive (Ar) and aggregative (Ar). Results. The results of comparative and correlation analyses demonstrated that young athletes with +9/-9 (BDKRB2) genotype were characterized by a higher aggregative resistance of erythrocytes to the effects of both physiological (<10-9 g/ml) (physiological adrenaline concentration, PAC) and stressful doses (>10-9 g/ml) of adrenaline (stress adrenaline concentration, SAC), as well as by predominance of AnAg and Ar ARE types. In athletes, among the representatives of different genotypes of АСЕ gene I/D polymorphism, the erythrocyte response to adrenaline did not have any statistically significant differences. In physically inactive students, namely individuals with the D/D genotype, maximal ESR deviation under PAC was less than in those with I/D genotype. Conclusion. Athletes with *-9 allele (+9/-9 genotype) in their genotype can be considered more stress-resistant, which is provided by optimal adaptive and compensatory body mechanisms. Apparently, resistance of cells to the adrenaline contributes much to the work of these mechanisms. As for the ACE gene polymorphism, its effect on the suspension characteristics of erythrocytes is less pronounced not only in physically inactive young men, but in athletes as well. Keywords: erythrocyte adrenoreactivity (ARE), stress tolerance, β2 bradykinin receptor gene (BDKRB2), angiotensin converting enzyme (ACE) gene, motor activity. Цель работы – изучить ассоциацию полиморфных вариантов rs4646994 (I/D) гена ангиотензинпревращающего фермента (АСЕ) и rs5810761 (+9/-9) гена рецептора брадикинина 2 типа (BDKRB2) с адренореактивностью эритроцитов (АРЭ) у спортсменов и юношей, ведущих физически малоактивный образ жизни. Материалы и методы. В исследовании принял участие 61 юноша с разным уровнем двигательной активности (ДА) в возрасте 21–23 лет. Оценку АРЭ проводили по изменению скорости оседания эритроцитов (СОЭ) под действием адреналина in vitro в конечных концентрациях 10-5, 10-6, 10-7, 10-8, 10-9, 10-11, 10-13 г/мл венозной крови. По характеру наблюдаемого эффекта в соответствии с направленностью сдвигов СОЭ в присутствии адреналина мы выделили 3 типа АРЭ: антиагрегационный (АнАг), ареактивный (Ар) и агрегационный (Аг). Результаты. По результатам сравнительного и корреляционного анализа установлено, что юноши-спортсмены с генотипом +9/-9 (BDKRB2) характеризуются более высокой агрегативной устойчивостью эритроцитов к воздействию как физиологических (10-9 г/мл и ниже), так и повышенных (стрессовых) доз (выше 10-8 г/мл крови) адреналина, а также преобладанием АнАг- и Ар-типов АРЭ. У представителей разных генотипов полиморфизма I/D гена АСЕ реакция эритроцитов на адреналин не имела статистически значимых различий в группе спортсменов, тогда как в группе малоактивных студентов у лиц с генотипом D/D максимальное отклонение СОЭ при ФКА было меньше, чем при генотипе I/D. Выводы. Спортсменов, имеющих в своём генотипе аллель *-9 (+9/-9 генотип), можно считать более стрессоустойчивыми, что обеспечивается оптимальными адаптивно-компенсаторными механизмами организма, существенная роль в обеспечении которых, по-видимому, принадлежит устойчивости клеток к действию адреналина. Что касается полиморфизма гена АСЕ, то его влияние на суспензионные характеристики эритроцитов выражено слабее не только у физически малоактивных юношей, но и у спортсменов. Ключевые слова: адренореактивность эритроцитов (АРЭ), стрессоустойчивость, ген рецептора брадикинина β2 (BDKRB2), ген ангиотензинпревращающего фермента (АСЕ), двигательная активность.

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