Structural basis for Mep2 ammonium transceptor activation by phosphorylation

Mep2 proteins are fungal transceptors that play an important role as ammonium sensors in fungal development. Mep2 activity is tightly regulated by phosphorylation, but how this is achieved at the molecular level is not clear. Here we report X-ray crystal structures of the Mep2 orthologues from Saccharomyces cerevisiae and Candida albicans and show that under nitrogen-sufficient conditions the transporters are not phosphorylated and present in closed, inactive conformations. Relative to the open bacterial ammonium transporters, non-phosphorylated Mep2 exhibits shifts in cytoplasmic loops and the C-terminal region (CTR) to occlude the cytoplasmic exit of the channel and to interact with His2 of the twin-His motif. The phosphorylation site in the CTR is solvent accessible and located in a negatively charged pocket ∼30 Å away from the channel exit. The crystal structure of phosphorylation-mimicking Mep2 variants from C. albicans show large conformational changes in a conserved and functionally important region of the CTR. The results allow us to propose a model for regulation of eukaryotic ammonium transport by phosphorylation

POACEA FAMILY CROPS: REVIEW

The poacea family is one of the most large families in the plant of Monocotyledon, one of the floral plants. There are about 600 species in this family and about 10,000 genus, including the most important crops such as wheat, rice, maize, barley, oats and millet. This family contains a lot of forage crops and grass plants

Analysis of spheroidized AISI 1050 steel in terms of cutting forces and surface quality

In this study, the effects of microstructure differences obtained with the application of different spheroidizing heat treatment cycles on medium carbon steel on cutting forces and surface roughness values were investigated. For this purpose, a group of AISI 1050 materials was annealed at 700 degrees C below A(c1). temperature for 720 min and cementite phases were spheroidized by the traditional method. Another group of materials was quenched after austenitization at 850 degrees C for 15 min and then cementites were spheroidized in the ferrite matrix by over-tempering separately at 600 degrees C for 15 and 60 min and at 700 degrees C for 60 min. Machining of the samples was tested under dry cutting conditions in CNC turning center with SNMG 120408 cementite carbide cutting tool and proper PSBNR 2525M12 tool holder with 75-degree edge angle. Cutting forces of traditionally spheroidized samples were lower than the samples spheroidized after quenching. In addition, their cutting forces decreased due to the increase in the average sizes of spheroidal cementite. Minimum surface roughness value was obtained from the samples which were spheroidized at 600 degrees C for 15 min after quenching. However, surface roughness rate of the sample increased as spheroidizing time increased

Transport mechanisms in the ammonium transporter family

Ammonium transport is mediated by membrane proteins of the ubiquitous Amt/Rh family. Despite the availability of different X-ray structures that provide many insights on the ammonium permeation process, the molecular details of its mechanism remain controversial. The X-ray structures have revealed that the pore of the Amt and Rh proteins is characterized by a hydrophobic portion about 12A long in which electronic density was observed in crystallographic study of AmtB from Escherichia coli. This electronic density was initially only observed when crystals were grown in presence of ammonium salt and was thus attributed to ammonia (NH(3)) molecules, and lead the authors to suggest that the conduction mechanism in the Amt/Rh proteins involves the single-file diffusion of NH(3) molecules. However, other X-ray crystallography results and molecular mechanics simulations suggest that the pore of AmtB could also be filled with water molecules. The possible presence of water molecules in the pore lumen calls for a reassessment of the growing consensus that Amt/Rh proteins work as plain NH(3) channels. Indeed, functional experiments on plant ammonium transporters and rhesus proteins suggest a variety of permeation mechanisms including the passive diffusion of NH(3), the antiport of NH(4)(+)/H(+), the transport of NH(4)(+), or the cotransport of NH(3)/H(+). We discuss these mechanisms in light of some recent functional and simulation studies on the AmtB transporter and illustrate how they can be reconciled with the available high resolution X-ray data

Knowledge accumulation at the regional level and the role of intellectual property rights

There has been a growing debate on the role of intellectual property rights (IPR) in the accumulation of knowledge and more recently on the role they play in ensuring long-term economic growth by supporting knowledge creation and expansion, incentivizing investment in R;D and innovation. This research aims to reveal the effects of industrial property rights on regional economic development in Turkey. In addition, and recognizing the heterogeneity across regions within the same country, we conduct the analysis with a caveat, by differentiating the effect across developed and developing regions. Our results suggest that industrial property rights have played a dual role, first by promoting the effort on investment in innovation activities measured as R;D intensity, and the amount of R;D employees, and second, by contributing to economic development. However, the impact differs between developed and developing regions. © 2023 Informa UK Limited, trading as Taylor ; Francis Group

Scrutinizing innovation performance of family firms in efficiency-driven environment

Although family firms constitute the bulk of economic activity in many world economies, their behavior is still far from understood. This is particularly true when it comes to innovation activities of family firms in efficiency-driven environments with limited indigenous innovation potential, low quality of innovation systems and weak innovation policies. The sample consisting of 293 family firms and we reveal that in such setting internal competencies, collaboration, and public support facilitate innovativeness and diminish the negative effects of firm maturity and innovation barriers among family firms. Tacit RandD knowledge and internal absorptive capacity outweigh the negative effects on innovation of family firms

Trisubstituted-imidazoles induce apoptosis in human breast cancer cells by targeting the oncogenic PI3K/Akt/mTOR signaling pathway

10.1371/journal.pone.0153155PLoS ONE114e015315