The Calculation of Parameters for DNA Kinetic Structure Based on Monte-Carlo Multiple Integrals

Based on protein-DNA complex crystal structural data in up-to-date Nucleic Acid Database,the related parameters of DNA Kinetic Structure were investigated by Monte-Carlo Multiple Integrals on the base of modified DNA structure statistical mechanical model,and time complexity and precision were analyzed on the calculated results.

Synthesis,crystal structures of novel complexes of rare earth with norfloxacin,interaction with DNA and BSA

Three novel rare earth complexes [N（CH 3） 4 ][Ln（NF） 4 ]·6H 2 O（Ln=Nd（III）（1）,Sm（III）（2）,Ho（III）（3）） were synthesized using hydrothermal method from norfloxacin HNF=1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-（1-piperazinyl）-3-quinoline carboxylic acid,C 16 H 18 FN 3 O 3）,imidazole and rare earth nitrates.The complexes were characterized by elemental analysis,FT-IR,TG-DTG and X-ray single crystal diffraction.Each rare earth ion was eight-coordinated with carboxyl-O atoms and keto-O atoms from norfloxacin.Four of the norfloxacin ions acted as bidentate chelate group took part in the coordination with rare earth ion.The structures of complexes were tetragonal system with space group I4 1 /acd,which were allomerism.The interaction between complex 1 and DNA was studied by electronic absorption spectra and fluorescence spectroscopy.The binding interaction between the complex 1 and bovine serum albumin（BSA） was studied by fluorescence spectroscopy.The complex 1 bound to DNA by the mode of partial intercalation.Complex 1 had a strong ability to quench the fluorescence from BSA.The complex interaction was mainly a static quenching process with BSA together with formation of two binding sites.

Structural basis of DNA binding by the NAC transcription factor ORE1,a master regulator of plant senescence

Plants use sophisticated mechanisms of gene expression to control senescence in response to environmental stress or aging.ORE1(Arabidopsis thaliana NAC092)is a master regulator of senescence that belongs to the plant-specific NAC transcription factor protein family.ORE1 has been reported to bind to multiple DNA targets to orchestrate leaf senescence,yet the mechanistic basis for recognition of the cognate gene sequence remains unclear.Here,we report the crystal structure of the ORE1-NAC domain alone and its DNA-binding form.The structure of DNA-bound ORE1-NAC revealed the molecular basis for nucleobase recognition and phosphate backbone interactions.We showthat local versatility in the DNA-binding site,in combination with domain flexibility of the ORE-NAC homodimer,is crucial for the maintenance of binding to intrinsically flexible DNA.Our results provide a platformfor understanding other plant-specific NAC protein-DNA interactions as well as insight into the structural basis of NAC regulators in plants of agronomic and scientific importance.

The CARMA3-BCL10-MALT1 （CBM） complex contributes to DNA damage-induced NF-κB activation and cell survival

Dear Editor,Chemotherapy is one of major means for cancer treatments, and many of chemotherapeutic drugs are DNA damaging agents that reduce tumor growth through triggering cancer cell apoptosis or necrosis. Following DNA damage, ataxia telangiectasia mutated （ATM）, a protein kinase, was acti- vated and a cytosolic complex containing ATM, NEMO, RIP1 were formed （Biton and Ashkenazi, 2011）.

Mesoporous silica nanoparticles-assisted ruthenium(Ⅱ) complexes for live cell staining

Ruthenium complexes which can bind to DNA via electrostatic and intercalation interactions producing strong luminescence have become ideal candidates for DNA staining. However, some of them such as Ru(phen)_3Cl_2 and Ru(phen)_2(dppz)Cl_2 could hardly cross the cellular membrane of live cells which limited their further interaction with DNA in live cells. To solve this problem, a potential approach is to find a proper vehicle for loading and delivery of these ruthenium complexes into live cells.Mesoporous silica nanoparticles(MSNs) with non-toxicity and good biocompatibility can be good candidates. More importantly,ruthenium complexes with positively charge could be loaded on negatively charged MSNs via electrostatic attractions to form MSNs-Ru hybrid. In vitro test demonstrated that MSNs had no side effects on the interactions between Ru complexes and DNA.Furthermore, it is found that the MSNs-Ru hybrid can enter into living human cervical cancer cells HeLa and stain the DNA while the corresponding ruthenium complexes alone could hardly cross the cellular membrane in the control experiment, demonstrating MSNs can be employed to be an efficient ruthenium complexes delivery nanomaterial for live cell staining.