Search

Arginine methylation modulates diverse cellular processes and represents a molecular signature of germ-line-specific Piwi family proteins. A subset of Tudor domains recognize arginine methylation modifications, but the binding mechanism has been lacking. Here we establish that, like other germ-line Tudor proteins, the ancestral staphylococcal nuclease domain-containing 1(SND1) polypeptide is expressed and associates with PIWIL1/Miwi in germ cells. We find that human SND1 binds PlWlL1 in an arginine methylation-dependent manner with a preference for symmetrically dimethylated arginine. The entire Tudor domain and a bifurcated SN domain are required for this binding activity, whereas the canonical Tudor domain alone is insufficient for methylarginine ligand binding. Crystal structures show that the intact SND1 extended Tudor domain forms a wide and negatively charged binding groove, which can accommodate distinct symmetrically dimethylated arginine peptides from PlWlL1 in different orientations. This analysis explains how SND1 preferentially recognizes symmetrical dimethylarginine via an aromatic cage and conserved hydrogen bonds, and provides a general paradigm for the binding mechanisms of methylarginine-containing peptides by extended Tudor domains. Piwi-interacting RNA | Tudor domain-containing proteins doi/ 10.1073/pnas.1013106107

Comparative genomic studies have identified many proteins that are found only in various Chlamydiae species and exhibit no significant sequence similarity to any protein in organisms that do not belong to this group. The CT670 protein of Chlamydia trachomatis is one of the proteins whose genes are in one of the type III secretion gene clusters but whose cellular functions are not known. CT670 shares several characteristics with the YscO protein of Yersinia pestis, including the neighboring genes, size, charge, and secondary structure, but the structures and/or functions of these proteins remain to be determined. Although a BLAST search with CT670 did not identify YscO as a related protein, our analysis indicated that these two proteins exhibit significant sequence similarity. In this paper, we report that the CT670 crystal, solved at a resolution of 2 [Angstrom], consists of a single coiled coil containing just two long helices. Gel filtration and analytical ultracentrifugation studies showed that in solution CT670 exists in both monomeric and dimeric forms and that the monomer predominates at lower protein concentrations. We examined the interaction of CT670 with many type III secretion system-related proteins (viz., CT091, CT665, CT666, CT667, CT668, CT669, CT671, CT672, and CT673) by performing bacterial two-hybrid assays. In these experiments, CT670 was found to interact only with the CT671 protein (YscP homolog), whose gene is immediately downstream of ct670. A specific interaction between CT670 and CT671 was also observed when affinity chromatography pull-down experiments were performed. These results suggest that CT670 and CT671 are putative homologs of the YcoO and YscP proteins, respectively, and that they likely form a chaperone-effector pair. doi: 10.1128/JB.01479-09

Research has been conducted on the copper molybdate family. The structures and magnetic properties of bimetallic oxides [Cu(3,4'-bpy)MoO (sub)4], [Cu(3,3'-bpy) (sub)0.5 MoO (sub)4], and [Cu(4,4'-bpy) (sub)0.5 MoO (sub)4].1.5H (sub)2 O have been studied and the details are presented.

Results reveal that the new series of germanium antimonides are metallic and those containing RE = Nd, Sm, Gd-Dy exhibit kinks in their temperature resistivity behavior. Further, the compounds reveal long-range antiferromagnetic ordering in their atomic structures.

The structural characterization of a new series of germanium antimonides show that the rare-earth atom trigonal prism columns are separated by Ge and Sb atoms. The atoms exhibit interactions between them ranging from strong covalent bonds to intemediate partial bond to weak van der Waals forces.

A study is conducted on the nonstoichiometric ternary arsenide Ba0.8Hf12As17.7. The compound was synthesized by reacting the elements at 950 degrees Centrigrade in a tin flux. It is shown that Ba0.8Hf12As17.7 exhbits the unique feature of As ribbons inserted between isolated columnar assemblies of Hf6 trigonal prisms. The behavior and features of As-As bonding in Ba0.8Hf12As17.7 were also determined using extended Huckel band structure calculations.

The new Zintl phase Ba2Sn3Sb6 was synthesized and its structure was analyzed. Its structure is composed of large channels constructed from an anionic framework built up from Sn-centered trigonal pyramids and tetrahedra, as well as zigzag chains of Sb atoms. Ba2+ cations and additional isolated zigzag Sb-Sb chains were found within the channels. Ba2SnSb6 is a mixed-valence compound containing both tin(II) and tin(IV).

The novel application of the amine-activated poly-p-xylene (parylene A) platform as the backbone for the fabrication of a microfilm device is demonstrated. The results from the DNA fragmentation and spectroscopic analysis demonstrate the efficient and localized drug-eluting properties of the Parylene A polymeric bilayer.

The preparation of a new series of organic-inorganic materials of the oxovanadium/organophosphonate/M(II)-organoimine family is allowed by hydrothermal synthesis. The report stated that the hybrid materials exhibited a range of magnetic properties, reflecting the presence of a single type paramagnetic metal ion Cu(II) and two distinct paramagnetic ions Cu(II) and V(IV).