A putative DNA-binding domain in the NUCKS protein

We have studied the DNA-binding properties of a NUCKS-derived, synthetic peptide containing an extended GRP motif. This peptide binds to random-sequence DNA, but did not bind preferentially to poly(dA-dT). A synthetic peptide with the same amino acid composition but with a random sequence did not bind to DNA, suggesting that the structure of the DNA-binding domain plays a pivotal role in the interaction with DNA. NMR and graphic modeling were employed to investigate the structure of the synthetic peptide. It was shown that the DNA-binding peptide constituted an alpha helix in phosphate buffer at pH 5.5. Docking results indicated an almost perfect fit for this small, helical peptide into the major groove of DNA with the possibility of four basic residues interacting with the phosphate backbone of DNA. One consensus site for phosphorylation by Cdk1 is located in the N-terminal end of the DNA-binding peptide. Upon phosphorylation of this site, the binding to DNA was completely prohibited. Immunofluorescence experiments showed that NUCKS was located in the nuclei in proliferating cells in interphase of the cell cycle, but was distributed throughout the cytoplasm in mitotic cells.     

X-Ray crystallographic, NMR and antimicrobial activity studies of magnesium complexes of fluoroquinolones - racemic ofloxacin and its S-form, levofloxacin

The magnesium complexes of racemic ofloxacin (oflo) and its pure S-form levofloxacin (S-oflo) have been studied by X-ray crystallography and NMR spectroscopy. Two compounds, [Mg(R-oflo)(S-oflo)(H(2)O)(2)].2H(2)O (1) and [Mg(S-oflo)(2)(H(2)O)(2)].2H(2)O (2), respectively, have been prepared by hydrothermal reactions and their crystal structures have been determined. In both structures the anionic fluoroquinolone ligands are coordinated through the keto and carboxylate oxygens forming 1:2 Mg:oflo complexes. The two structures are practically identical except for the orientation of one of the oxazine methyl groups at the chiral center of 2 which was found in equatorial position, the other oxazine methyl groups in 1 and 2 being axial. This difference affects the stacking pattern of quinolone molecules in the cell. (1)H NMR chemical shift data and Mn(II) paramagnetic line broadening measurements on the free ofloxacin suggest that the coordination of the ligands in solution involves the keto and carboxylate oxygens. However, it is not possible to decide whether the complexes in aqueous solution have 1:1 or 1:2 stoichiometry. The methylated piperazine nitrogen does not interact with the metal ion. Magnesium-quinolone interaction is discussed in relation to the biological activity of quinolones. The antimicrobial activity of the complexes against various microorganisms was tested and it was established that their activity is similar to that of free quinolone drugs.     

Microfluidic study of effects of flow velocity and nutrient concentration on biofilm accumulation and adhesive strength in the flowing and no-flowing microchannels

Journal of Industrial Microbiology & Biotechnology - Biofilm accumulation in porous media can cause pore plugging and change many of the physical properties of porous media. Engineering...