The structural basis of Cdc7-Dbf4 kinase dependent targeting and phosphorylation of the MCM2-7 double hexamer

The controlled assembly of replication forks is critical for genome stability. The Dbf4-dependent Cdc7 kinase (DDK) initiates replisome assembly by phosphorylating the MCM2-7 replicative helicase at the N-terminal tails of Mcm2, Mcm4 and Mcm6. At present, it remains poorly understood how DDK docks onto the helicase and how the kinase targets distal Mcm subunits for phosphorylation. Using cryo-electron microscopy and biochemical analysis we discovered that an interaction between the HBRCT domain of Dbf4 with Mcm2 serves as an anchoring point, which supports binding of DDK across the MCM2-7 double-hexamer interface and phosphorylation of Mcm4 on the opposite hexamer. Moreover, a rotation of DDK along its anchoring point allows phosphorylation of Mcm2 and Mcm6. In summary, our work provides fundamental insights into DDK structure, control and selective activation of the MCM2-7 helicase during DNA replication. Importantly, these insights can be exploited for development of novel DDK inhibitors

Effects of Chromium (Cr) doping on Structural, Electronic and Magnetic Properties of Barium Selenide Compound: A Theoretical Investigation

748-750The structural, electronics, and magnetic properties of Ba1-xCrxSe compound at doping concentrations, x=0.06, 0.12, and 0.25 were investigated using full potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT).The Wu-Cohen generalized-gradient approximation (WC-GGA) exchange correlation potentials were used to compute structural properties, while the electronic and magnetic properties were explored using the WC-GGA coupled with modified Becke-Johnson (mBJ) scheme. Our findings show that Ba1-xCrxSe are half-metallic ferromagnets (HMFs) having 100% spin polarization at Fermi level (EF). For investigated compounds, the half-metallic gap gets narrow out as doping concentration rises from 6% to 25%.All compounds are confirmed to be ferromagnetic since the Cr atom is able to induce an integral total magnetic moment of ~ 4.0 μB. By creating new states at EF as a result of fractional replacement of Cr at Ba site, half-metallicity and magnetism get developed, which makes them potentially relevant for spintronic applications

Head-on collision of nonlinear excitations in electron beam superthermal plasma

This study presents the head-on collision of electron-acoustic (EA) multi-solitons in an unmagnetized plasma with cold electron fluid, an electron beam, superthermal hot electrons with stationary ions. The extended Poincare–Lighthill–Kuo (PLK) approach is used to generate the Korteweg-de Vries equations. The Hirota bilinear approach has also been used to determine the multi-solitons solutions of KdV equations. Characteristics of EA solitons and phase shifts of multi-soliton under the combined effects of electron beam parameters and other different physical parameters have been studied. It is noted that the phase shifts and other features of EA solitons are strongly influenced by the presence of an electron beam and other plasma parameters. This study could be very significant for understanding the characteristics of nonlinear structures in various types of plasma, particularly in the Earth’s magnetosphere