The spliceosome-activating complex: molecular mechanisms underlying the function of a pleiotropic regulator

Correct interpretation of the coding capacity of RNA polymerase II transcribed eukaryotic genes is determined by the recognition and removal of intronic sequences of pre-mRNAs by the spliceosome. Our current knowledge on dynamic assembly and subunit interactions of the spliceosome mostly derived from the characterization of yeast, Drosophila, and human spliceosomal complexes formed on model pre-mRNA templates in cell extracts. In addition to sequential structural rearrangements catalyzed by ATP-dependent DExH/D-box RNA helicases, catalytic activation of the spliceosome is critically dependent on its association with the NineTeen Complex (NTC) named after its core E3 ubiquitin ligase subunit PRP19. NTC, isolated recently from Arabidopsis, occurs in a complex with the essential RNA helicase and GTPase subunits of the U5 small nuclear RNA particle that are required for both transesterification reactions of splicing. A compilation of mass spectrometry data available on the composition of NTC and spliceosome complexes purified from different organisms indicates that about half of their conserved homologs are encoded by duplicated genes in Arabidopsis. Thus, while mutations of single genes encoding essential spliceosome and NTC components lead to cell death in other organisms, differential regulation of some of their functionally redundant Arabidopsis homologs permits the isolation of partial loss of function mutations. Non-lethal pleiotropic defects of these mutations provide a unique means for studying the roles of NTC in co-transcriptional assembly of the spliceosome and its crosstalk with DNA repair and cell death signaling pathways

Antibody Evasion by a Gammaherpesvirus O-Glycan Shield

All gammaherpesviruses encode a major glycoprotein homologous to the Epstein-Barr virus gp350. These glycoproteins are often involved in cell binding, and some provide neutralization targets. However, the capacity of gammaherpesviruses for long-term transmission from immune hosts implies that in vivo neutralization is incomplete. In this study, we used Bovine Herpesvirus 4 (BoHV-4) to determine how its gp350 homolog - gp180 - contributes to virus replication and neutralization. A lack of gp180 had no impact on the establishment and maintenance of BoHV-4 latency, but markedly sensitized virions to neutralization by immune sera. Antibody had greater access to gB, gH and gL on gp180-deficient virions, including neutralization epitopes. Gp180 appears to be highly O-glycosylated, and removing O-linked glycans from virions also sensitized them to neutralization. It therefore appeared that gp180 provides part of a glycan shield for otherwise vulnerable viral epitopes. Interestingly, this O-glycan shield could be exploited for neutralization by lectins and carbohydrate-specific antibody. The conservation of O-glycosylation sites in all gp350 homologs suggests that this is a general evasion mechanism that may also provide a therapeutic target

Who Opposes Climate Regulation? Business Preferences for the European Emission Trading Scheme

When do firms oppose international climate policy? Existing work often assumes that firms disapprove of climate regulation due to the immediate costs of compliance. We claim that if policy is implemented gradually, private preferences for climate policy vary as a function of its progressive stringency. That is, supportive views may rise in the initial phase of the policy, while opposing views may emerge as the policy becomes more stringent. We also argue that emissions of individual companies, as well as emissions levels in their respective sectors, influence corporate positions on these two dimensions. We test our argument with new corporate survey data on the European Union Emission Trading Scheme (EU ETS). We find that firms’ views on the performance of the EU ETS vary based on whether they concentrate on the policy’s current state or its future, more stringent development. Moreover, we find that individual firm and sectoral emissions correlate with support for the early-stage, more lenient version of the ETS, but that high-emission firms are more interested in disinvesting and relocating if the ETS becomes stricter. Our findings imply that both firm and sectoral organization can constrain environmental regulation, and that domestic compensation, especially at early stages, can have important effects on the success of climate policy

MOESM4 of LEAFDATA: a literature-curated database for Arabidopsis leaf development

Additional File 4: Table S3. List of papers curated in LEAFDATA