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The RNA-activated protein kinase PKR inhibits translation initiation by sensing long viral double-stranded RNA. A new report indicates that PKR is also activated by a cellular mRNA, but only when ribosomes are not initiating translation.
Two iron regulatory proteins (IRP1 and IRP2) regulate translation and/or stability of mRNAs encoding proteins required for iron storage, acquisition and utilization. Rather than IRP2 directly sensing iron concentrations, iron has been shown to regulate the level of the SKP1-CUL1-FBXL5 E3 ubiquitin ligase protein complex, which is responsible for IRP2 degradation.
Vibrio cholerae produces cholera autoinducer-1 (CAI-1), a signaling molecule previously believed to be synthesized by the CqsA enzyme. Here it is shown that CqsA does not directly synthesize CAI-1; instead, it synthesizes amino-CAI-1, which is then converted into CAI-1 in a CqsA-independent manner.
A unique heterotrimeric assembly of individually inactive paralogs, two of which are also involved in regulating phosphatase activity, creates one of the key enzymes of coenzyme A biosynthesis in yeast, pointing to the possibility of a previously undescribed cross-talk between metabolic and signaling pathways.
Inorganic nitrate and nitrite from endogenous or dietary sources are metabolized in vivo to nitric oxide (NO) and other bioactive nitrogen oxides. The nitrate-nitrite-NO pathway is emerging as an important mediator of blood flow regulation, cell signaling, energetics and tissue responses to hypoxia. The latest advances in our understanding of the biochemistry, physiology and therapeutics of nitrate, nitrite and NO were discussed during a recent 2-day meeting at the Nobel Forum, Karolinska Institutet in Stockholm.
Synthetic biologists aim to rationally design and construct useful biological circuits. However, perturbation of host cell physiology, through the very process of turning on an artificial circuit, can give rise to unexpected emergent behaviors, such as bistability.
Few antimicrobial drugs function by directly targeting RNA. A small molecule that binds the hepatitis C viral genome by 'locking' in a particular RNA conformation to inhibit viral protein production suggests a new paradigm for drug design.
Membrane curvature sensing by amphipathic helices is an emergent property of the ensemble of molecules and membrane sites. New data suggest that individual molecules do not experience stronger binding to curved membranes.
Parathyroid hormone (PTH) and PTH-related protein activate the same receptor but can produce divergent effects. Reports now describe two active conformations for the PTH receptor, one of which moves intracellularly—complexed with hormone and G protein—to produce a continued cAMP signal.
Hydrolysis of the phosphodiester linkages in DNA is a notoriously difficult reaction. Deoxyribozymes that use Zn2+ and Mn2+ ions to accelerate this reaction by a factor of one hundred million (or more) have been identified and characterized.
Chemo-metabolic processes such as redox remodeling and amino acid availability act as immunity rheostats, revealing a new mechanism regulating intercellular cross-talk between dendritic cells, regulatory T lymphocytes and effector T lymphocytes.
The functional architecture of dimeric or oligomeric GPCR signaling remains incompletely understood. Using a clever combination of receptor–G protein fusions and various receptor mutations, new research provides a glimpse into how oligomers might be arranged with respect to the G proteins they interact with.
