Nature Structural & Molecular Biology 15, 531 (2008). doi:10.1038/nsmb.1411

Authors: Harrison W Gabel & Gary Ruvkun

The exonuclease ERI-1 negatively regulates RNA interference in Caenorhabditis elegans and Schizosaccharomyces pombe, and is required for production of some C. elegans endogenous small interfering RNAs. We show that ERI-1 performs 3′ end processing of the 5.8S ribosomal RNA in both C. elegans and S. pombe. In C. elegans, two protein isoforms of ERI-1 are localized to the cytoplasm, and each has distinct functions in ribosomal RNA processing and negative regulation of RNA interference.

Nature Structural & Molecular Biology 15, 534 (2008). doi:10.1038/nsmb.1408

Authors: Zhili Xu, Heather C O'Farrell, Jason P Rife & Gloria M Culver

In contrast to the diversity of most ribosomal RNA modification patterns and systems, the KsgA methyltransferase family seems to be nearly universally conserved along with the modifications it catalyzes. Our data reveal that KsgA interacts with small ribosomal subunits near functional sites, including Initiation factor 3 and 50S subunit binding sites. These findings suggest a checkpoint role for this modification system and offer a functional rationale for the unprecedented level of conservation.

Nature Structural & Molecular Biology 15, 425 (2008). doi:10.1038/nsmb0508-425

If the United States is losing its competitive edge in science and technology, how can we begin to reverse that trend?

Nature Structural & Molecular Biology 15, 426 (2008). doi:10.1038/nsmb0508-426

Authors: Corina Maeder & Christine Guthrie

The splicing pathway is dominated by ATP-dependent RNA rearrangements promoted by DEAD-box helicases. Post-translational modifications have now been implicated in the regulation of two DEAD-box proteins that are required for catalytic activation of the spliceosome.

Nature Structural & Molecular Biology 15, 428 (2008). doi:10.1038/nsmb0508-428

Author: Katrina T Forest

A heterotrimeric complex of minor pseudopilins from the type II secretion system has been identified and its crystal structure solved. Although each subunit shares the same overall α-β fold as other characterized (pseudo)pilins, GspK has a unique large α-helical domain inserted between two canonical β-strands. The structure constrains models for pseudopilus assembly.

Nature Structural & Molecular Biology 15, 430 (2008). doi:10.1038/nsmb0508-430

Authors: Jiri Lukas & Jiri Bartek

Chromosomal breaks destabilize the genome and can cause developmental defects and diseases such as cancer. New work suggests that, shortly after DNA damage, dissociation of the histone binding protein HP1β from chromatin facilitates restoration of genome integrity.

Nature Structural & Molecular Biology 15, 432 (2008). doi:10.1038/nsmb0508-432

Authors: Aaron J Gottschalk, Ronald C Conaway & Joan Weliky Conaway

Since the discovery that actin and actin-related proteins (ARPs) reside in the nucleus as integral subunits of chromatin-modifying and chromatin-remodeling complexes, efforts to uncover their roles in chromatin regulation have met with limited success. In a new study, the previously mysterious helicase-SANT–associated (HSA) domain found in many chromatin regulatory complexes is shown to act as a module that directs recruitment and contributes to the action of actin and ARPs in chromatin regulation.