A broad overview of the achievements and emerging areas in the field of Green Chemistry.

This article provides a bird's-eye-view of the status and scale of commercialized and nascent nanotechnologies in the context of global element cycles to prioritize and guide relevant environmental health research.

Carbonassisted catalyst pretreatment enables straightforward synthesis of high-density carbon nanotube forests. Carbon

At the center of the nuclear pore complex (NPC) is a uniquely versatile central transport channel. Structural analyses of distinct segments ("protomers") of the three "channel" nucleoporins yielded a model for how this channel is constructed. Its principal feature is a midplane ring that can undergo regulated diameter changes of as much as an estimated 30 nm. To better understand how a family of "adaptor" nucleoporins-concentrically surrounding this channel-might cushion these huge structural changes, we determined the crystal structure of one adaptor nucleoporin, Nup157. Here, we show that a recombinant Saccharomyces cerevisiae Nup157 protomer, representing two-thirds of Nup157 (residues 70-893), folds into a seven-bladed β-propeller followed by an α-helical domain, which together form a C-shaped architecture. Notably, the structure contains a large patch of positively charged residues, most of which are evolutionarily conserved. Consistent with this surface feature, we found that Nup157 70-893 binds to nucleic acids, although in a sequence-independent manner. Nevertheless, this interaction supports a previously reported role of Nup157, and its paralogue Nup170, in chromatin organization. Based on its nucleic acid binding capacity, we propose a dual location and function of Nup157. Finally, modeling the remaining C-terminal portion of Nup157 shows that it projects as a superhelical stack from the compact C-shaped portion of the molecule. The predicted four hinge regions indicate an intrinsic flexibility of Nup157, which could contribute to structural plasticity within the NPC.gene gating | X-ray crystallography | DNA-binding protein | RNA-binding protein M ultiple copies of only ∼30 distinct proteins, collectively termed nucleoporins (nups), form a large nuclear pore complex (NPC) that, in vertebrates, amounts to an estimated mass of more than 100 MDa. Purification of sufficient quantities of intact and monodisperse NPCs that would be suitable for crystallographic analyses is presently not feasible. In an alternative approach, a recombinant full-length nup, or a nup fragment ("protomer"), or complexes thereof, are crystallized and their atomic structures are modeled into higher-order assemblies that represent distinct regions of the NPC (reviewed in ref. 1).Arguably, the most notable insights stemming from the aforementioned strategy were obtained from the crystal structures of protomers representing several structured regions of the three "channel" nups, Nup58, Nup54, and Nup62 (2-4). The outcome of these crystallographic analyses was a model of the atomic structure of the central transport channel, the heart of the NPC. The crucial features of this model are midplane rings that undergo dramatic structural rearrangements from the dilated to constricted state of the nuclear pore. In the dilated state, helical segments of four Nup58 and eight Nup54 protomers form a dodecameric module. The arrangement of eight such dodecamers results in a single, heterooligomeric midplane ring with a flexible diameter of 40 to 50...