Processive Movement by a Kinesin Heterodimer with an Inactivating Mutation in One Head†

ABSTRACT: A single molecule of the motor enzyme kinesin-1 keeps a tight grip on its microtubule track, making tens or hundreds of discrete, unidirectional 8 nm steps before dissociating. This high duty ratio processive movement is thought to require a mechanism in which alternating stepping of the two head domains of the kinesin dimer is driven by alternating, overlapped cycles of ATP hydrolysis by the two heads. The R210K point mutation in Drosophila kinesin heavy chain was reported to disrupt the ability of the enzyme active site to catalyze ATP P-O bond cleavage. We expressed R210K homodimers as well as isolated R210K heads and confirmed that both are essentially inactive. We then coexpressed tagged R210K subunits with untagged wild-type subunits and affinity purified R210K/wild-type heterodimers together with the inactive R210K homodimers. In contrast to the R210K head or homodimer, the heterodimer was a highly active (>50 % of wild-type) microtubule-stimulated ATPase, and the heterodimer displayed high duty ratio processive movement in single-molecule motility experiments. Thus, dimerization of a subunit containing the inactivating mutation with a functional subunit can complement the mutation; this must occur either by lowering or by bypassing kinetic barriers in the ATPase or mechanical cycles of the mutant head. The observations provide support for kinesin-1 gating mechanisms in which one head stimulates the rate of essential processes in the other

Synthesis and characterization of BaTiO3/-Fe2O3 core/shell structure

Multiferroic materials attracted a lot of attention in recent years because of their significant scientific interest and technological applications. The multiferroic core/shell powders have a better connectivity between the phases, resulting in superior dielectric and magneto electric properties. In this study, the influence of preparation condition on structure and properties of BaTiO3/-Fe2O3 core/shell composite materials was examined. The five samples were obtained by varying synthesis conditions, such as synthesized method (co-precipitation and sonochemical method) and pH values of solution. XRD and Raman spectroscopy analyses were performed in order to determine phase composition and structural changes within samples. Morphology modifications were examined by SEM and EDS analyses. Finally, effect of structural and microstructural changes on magnetic and electrical properties was detected and explained

Four signature motifs define the first class of structurally related large coiled-coil proteins in plants.

BACKGROUND: Animal and yeast proteins containing long coiled-coil domains are involved in attaching other proteins to the large, solid-state components of the cell. One subgroup of long coiled-coil proteins are the nuclear lamins, which are involved in attaching chromatin to the nuclear envelope and have recently been implicated in inherited human diseases. In contrast to other eukaryotes, long coiled-coil proteins have been barely investigated in plants. RESULTS: We have searched the completed Arabidopsis genome and have identified a family of structurally related long coiled-coil proteins. Filament-like plant proteins (FPP) were identified by sequence similarity to a tomato cDNA that encodes a coiled-coil protein which interacts with the nuclear envelope-associated protein, MAF1. The FPP family is defined by four novel unique sequence motifs and by two clusters of long coiled-coil domains separated by a non-coiled-coil linker. All family members are expressed in a variety of Arabidopsis tissues. A homolog sharing the structural features was identified in the monocot rice, indicating conservation among angiosperms. CONCLUSION: Except for myosins, this is the first characterization of a family of long coiled-coil proteins in plants. The tomato homolog of the FPP family binds in a yeast two-hybrid assay to a nuclear envelope-associated protein. This might suggest that FPP family members function in nuclear envelope biology. Because the full Arabidopsis genome does not appear to contain genes for lamins, it is of interest to investigate other long coiled-coil proteins, which might functionally replace lamins in the plant kingdom

Activating Transcription Factor 4 Modulates TGFβ-Induced Aggressiveness in Triple-Negative Breast Cancer via SMAD2/3/4 and mTORC2 Signaling

Purpose: On the basis of the identified stress-independent cellular functions of activating transcription factor 4 (ATF4), we reported enhanced ATF4 levels in MCF10A cells treated with TGFβ1. ATF4 is overexpressed in patients with triple-negative breast cancer (TNBC), but its impact on patient survival and the underlying mechanisms remain unknown. We aimed to determine ATF4 effects on patients with breast cancer survival and TNBC aggressiveness, and the relationships between TGFβ and ATF4. Defining the signaling pathways may help us identify a cell signaling-tailored gene signature.Experimental Design: Patient survival data were determined by Kaplan-Meier analysis. Relationship between TGFβ and ATF4, their effects on aggressiveness (tumor proliferation, metastasis, and stemness), and the underlying pathways were analyzed in three TNBC cell lines and in vivo using patient-derived xenografts (PDX).Results: ATF4 overexpression correlated with TNBC patient survival decrease and a SMAD-dependent crosstalk between ATF4 and TGFβ was identified. ATF4 expression inhibition reduced migration, invasiveness, mammosphere-forming efficiency, proliferation, epithelial-mesenchymal transition, and antiapoptotic and stemness marker levels. In PDX models, ATF4 silencing decreased metastases, tumor growth, and relapse after chemotherapy. ATF4 was shown to be active downstream of SMAD2/3/4 and mTORC2, regulating TGFβ/SMAD and mTOR/RAC1-RHOA pathways independently of stress. We defined an eight-gene signature with prognostic potential, altered in 45% of 2,509 patients with breast cancer.Conclusions: ATF4 may represent a valuable prognostic biomarker and therapeutic target in patients with TNBC, and we identified a cell signaling pathway-based gene signature that may contribute to the development of combinatorial targeted therapies for breast cancer

Effect of Dietary Advanced Glycation End Products on Mouse Liver

The exact pathophysiology of non-alcoholic steatohepatitis (NASH) is not known. Previous studies suggest that dietary advanced glycation end products (AGEs) can cause oxidative stress in liver. We aim to study the effects of dietary AGEs on liver health and their possible role in the pathogenesis of NASH. METHODS: Two groups of mice were fed the same diet except the AGE content varied. One group was fed a high AGE diet and the second group was fed a regular AGE diet. Liver histology, alanine aminotransferase, aspartate aminotransferase, fasting glucose, fasting insulin, insulin resistance and glucose tolerance were assessed. RESULTS: Histology revealed that neutrophil infiltration occurred in the livers of the high AGE group at week 26; steatosis did not accompany liver inflammation. At week 39 livers from both groups exhibited macro- or micro-steatosis, yet no inflammation was detected. Higher insulin levels were detected in the regular AGE group at week 26 (P = 0.034), compared to the high AGE group. At week 39, the regular AGE group showed higher levels of alanine aminotransferase (P<0.01) and aspartate aminotransferase (P = 0.02) than those of the high AGE group. CONCLUSIONS: We demonstrate that a high AGE diet can cause liver inflammation in the absence of steatosis. Our results show that dietary AGEs could play a role in initiating liver inflammation contributing to the disease progression of NASH. Our observation that the inflammation caused by high AGE alone did not persist suggests interesting future directions to investigate how AGEs contribute to pro-oxidative and anti-oxidative pathways in the liver

Transformer power generators for wireless networks of self-powered sensors in intelligent buildings

W nowoczesnych budynkach bezprzewodowe sensory są stosowane nie tylko do wykrywania dymu, detekcji ruchu i kontroli dostępu ale również do systemów monitorowania bezpieczeństwa strukturalnego budynku w zakresie bezstykowego pomiaru przemieszczeń liniowych i kątowych oraz drgań ich konstrukcji. Ten niezwykle ważny obszar zastosowań wymusza poszukiwania nowych lepszych technologii pozwalających na ich miniaturyzację, co związane jest z eliminacją tradycyjnego bateryjnego zasilania tych urządzeń. Ten aspekt jest w szczególności istotny do monitorowania wibracji zabetonowanych elementów konstrukcyjnych w warunkach środowiskowych uniemożliwiających wymianę zużytych baterii. Polimerowy kompozyt tworzący strukturę transformatora magnetoelektrycznego (ME) składający się z mieszaniny ceramiki piezoelektrycznej i magnetostrykcyjnej w osnowie z materiału polimerowego (Poliamid) został wytworzony z przeznaczeniem d o tego typu aplikacji. Na wskutek oddziaływania pola magnetycznego następuje zmiana ukierunkowania domen ferromagnetycznych w materiale magnetostrykcyjnym powiązana z wytworzeniem naprężeń mechanicznych. Powstałe naprężenia zostają przeniesione przez poliamidową osnowę na materiał piezoelektryczny, gdzie na zasadzie efektu piezoelektrycznego następuje generacja napięcia oraz zmiana jego parametrów elektrycznych. Pomiary współczynników transformacji energii pola magnetycznego na elektryczną przeprowadzano metodą mostkową na podstawie analizy fazowej i amplitudowej impedancji. Wykazano, że praktycznym zastosowaniem otrzymanego transformatora magnetoelektrycznego mogą być generatory energii elektrycznej wykorzystujące w swej zasadzie działania konwersję energii drgań i pola magnetycznego na elektryczną w opisywanym materiale kompozytowym.In modern smart building wireless sensors applications are used not only for direct smoke and intruder detection but mainly for structural safety of buildings in non-contact measurement of linear and angular displacement as well as construction vibrations. This very important area of applications enforces the search for new and better technologies to their miniaturization, in a first place with elimination of batteries. This aspect is extremely significant in harsh environmental conditions for vibration monitoring of concreted structure. Polymer composite material for magnetoelectric (ME) transformer consisting of a mixture of piezoelectric and the magnetostrictive material in a polyamide matrix (polymer with amid bond) was manufactured for this application and has been tested in an AC magnetic field. The mechanical tensions created from reoriented ferromagnetic domains generate a voltage at the electrodes surfaces due to the piezoelectric effect via tensions transmitted by polyamide matrix. Measurements of these transformation coefficients is carried out by a bridge technique on the basis of the amplitude and phase impedance characteristics. Finally it was demonstrated that the practical application of the created composite can be ME Transformer for voltage generations in wireless sensor network systems

The use of a vision system for measuring the construction deflection

W pracy zaprojektowano oraz wykonano stanowisko pomiarowe do badania linii ugięcia belek i konstrukcji budowlanych z wykorzystaniem algorytmu suwmiarki wizyjnej. Zaprojektowanie stanowiska wiązało się z potrzebą powiązania analizy uzyskanego obrazu z kamery cyfrowej z zagadnieniem ugięcia belki. Wszystkie materiały i urządzenia wykorzystane do budowy stanowiska zostały dobrane w taki sposób, aby zoptymalizować stanowisko pod kątem wytrzymałości, lekkości i stabilności, a także zapewnić dokładny i jak najbardziej zautomatyzowany odczyt. Do budowy modelowej konstrukcji zostały wykorzystane profile stalowe, a układ pomiarowy został wykonany na bazie tensometrycznego czujnika nacisku i układu z mikrokontrolerem. Odczyt ugięcia belki jest realizowany poprzez program LabVIEW za pomocą modułu wizyjnego. Na zaprojektowanym stanowisku można, w praktyczny sposób, zmierzyć ugięcie belki obciążonej siłą skupioną. Pomiary dokonywane na stanowisku testowym są obarczone błędem wynikającym z użycia kamery internetowej o niskiej rozdzielczości, natomiast może być ono w przyszłości modernizowane do precyzyjnych badań z zakresu zagadnień z mechaniki budowli.In the study, a test stand for testing beams deflection lines and building structures using a calliper visual calliper algorithm was designed and made. Designing the stand was associated with the need to link the analysis of the image obtained from a digital camera to the issue of beam deflection. All materials and equipment used to build the stand were selected so as to optimize the stand for the strength, lightness and stability, and to ensure the most accurate and automated reading. To build the model structure, steel profiles were used, and the measurement system was made on the basis of a strain gauge pressure sensor and the setting with a microcontroller. Beam deflection reading is realised through the Labview program using a video module. On the designed stand it is possible, in a practical way, to measure the deflection of a beam loaded with concentrated forc. Measurements performed on the test stand are subject to errors resulting from the use of a webcam with low resolution, but it can be modernised in the future to precise tests on issues of structural mechanics

Piezoelectric actuator made from ceramics fiber

Współcześnie stosowane w szeroko pojętej automatyce i mechatronice urządzenia wykonawcze (aktuatory) stawiają duże wymagania inżynierii materiałowej. Materiałom przeznaczonym na aktuatory stawia się wysokie wymagania dotyczące ich twardości, sztywności oraz wytrzymałości i lekkości. Umożliwia to zwiększenie dokładności obróbki i miniaturyzację produktów. Największe zastosowanie w tego typu urządzeniach znalazły materiały piezoelektryczne. Aktuatory na bazie ceramiki piezoelektrycznej między innymi są wykorzystywane jako części układów napędowych w motoryzacji (piezoelektryczne wtryskiwacze paliwa), w automatyzacji procesów przemysłowych jako siłowniki do precyzyjnych robotów, w awionice do zmiany geometrii skrzydeł samolotów [1,2]. Największą ich zaletą jest wysoka wytrzymałość mechaniczna i duża odporność na trudne warunki oraz bardzo krótki czas reakcji poniżej 1 ms. Aktuatory tego typu wykonywane są najczęściej z litej ceramiki piezoelektrycznej, która jest materiałem kruchym o dużej gęstości. W artykule została zaproponowana innowacyjna metoda wytwarzania piezoceramicznych materiałów do aplikacji aktuatorowych w formie włókien ceramicznych pozwalającą na ominięcie ograniczeń związanych z naprężeniami wewnętrznymi ceramiki w formie objętościowej.The materials, from which present-day actuators are produced, are increasingly harder, stiffer and more durable, and lighter at the same time. This makes it possible to increase processing accuracy, and miniaturisation of products. Piezoelectric materials have found the widest application in this type of devices. Piezoelectric actuators are widely used nowadays as automotive drives (piezoelectric fuel injectors), in automation as servomotors for precise robots, as well as in airplanes to change the wings geometry. Their greatest advantage is high mechanical strength and high resistance to difficult conditions, and very short response time, less than 1 ms. Actuators of this type are usually made of solid piezoelectric ceramic, which is a brittle material with high density. This article proposes an innovative method of producing piezoceramic materials for actuator applications, in the form of ceramic fibers, which allows to bypass the limitations related to internal stresses in ceramic in volume (standard) form