Volume 7 Issue 7, July 2011

Metabolic engineers have long sought a rational approach to designing hybrid organisms with unique biosynthetic capabilities. Combining in silico pathway discovery with genome-scale modeling has now provided an engineered Escherichia coli capable of producing the unnatural fermentation product 1,4-butanediol at near-commercial levels.

Spiroacetal substructures introduce important conformational constraints into bioactive polyketide natural products. New research reveals a two-enzyme team responsible for this molecular origami in reveromycin A biosynthesis.

The combination of NMR spectroscopy and statistical mechanics represents a powerful approach to characterize the behavior of macromolecules. Two recent studies demonstrate that the application of this strategy to analyze chemical shift measurements can reveal complex mechanisms of protein regulation.

Phosphomimetic mutations at huntingtin (Htt) Ser13 and Ser16 within the conserved N-terminal 17-amino-acid domain profoundly suppresses its toxicity in cell and mouse models of Huntington's disease. New research reveals that cell stress acts as a stimulus for double phosphorylation of endogenous Htt, causing its nuclear translocation, and shows that certain chemicals can target such molecular processes in Huntington's disease cell models.

Antibiotics are critical defenses in the fight against bacterial infections, but they can also be used as probes to explore basic microbiology, including cell division, stress responses and cell wall biosynthesis, and will be valuable tools in deciphering bacterial networks and complexity.

PUF proteins bind RNA sequences through specific interactions between PUF repeats and adenine, guanine and uracil bases. A directed evolution approach has identified new PUF repeats that specifically bind cytosine, which enables the recognition of diverse RNA sequences by engineered PUF proteins.

A specific and potent inhibitor of the DNA damage response kinase ATR can exploit synthetic lethality between ATR and the related kinase ATM to sensitize ATM-defective cancer cells to ionizing radiation and DNA-damaging drugs.

Two crystal structures of a three-domain class II diterpene cyclase with substrate and product analogs provide new insights into the mechanistic pathway of this enzyme and illuminate evolutionary and functional relationships within terpenoid biosynthesis more generally.

FrsA is responsible for the metabolic switch between fermentation and respiration, but the basis for this function has been unknown. Biochemical, structural and in vivo analyses now demonstrate that FrsA is a cofactor-independent pyruvate decarboxylase and thus directly controls carbon flux.

A quantitative sensor of spatial and temporal dynamics of activity of the protein tyrosine kinase Src shows that its activity peaks 1–2 μm from the leading edge of cells undergoing lamellipodial membrane extension, and the activation is correlated with protrusion velocity.

The design and implementation of a high-yielding enzymatic route to 1,4-butanediol—a compound not known to be produced naturally—provides a compelling example of how metabolic engineering can be harnessed for the microbial conversion of carbohydrate feedstocks to desired small molecules.

Phosphorylation of the Huntington's disease protein Htt by CK2 leads to Htt nuclear translocation in response to stress. Inhibition of other kinase pathways can restore phosphorylation to hypophosphorylated Htt in Huntington's disease and may lead to a therapeutic strategy.

Investigations of reveromycin biosynthesis, including metabolite analysis, feeding experiments and in vitro tests of enzyme function, point to a two-step mechanism for formation of the central spiroacetal, in which RevG oxidizes a stable acyclic precursor and RevJ catalyzes the stereocontrolled cyclization.

Investigations of serine hydrolases have been frustrated by a lack of selective chemical inhibitors. Profiling of synthetically accessible 1,2,3-triazole ureas in cells and mice now identifies several effective compounds, application of which yields new insights into N-acetylation by APEH.