Articles in 2011

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.

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.

Single-molecule fluorescence resonance energy transfer allows visualization of three distinct phases of DNA digestion mediated by λ exonuclease and identifies base melting as a rate-limiting step in the reaction pathway.

SAM riboswitches are RNA elements that regulate bacterial gene expression in response to binding of the small-molecule metabolite S-adenosylmethionine. Assembly of a functional SAM-I riboswitch occurs hierarchically and involves magnesium-induced preorganization of the SAM binding site.

SAM riboswitches are RNA elements that regulate bacterial gene expression in response to binding of the small-molecule metabolite, S-adenosylmethionine. The SAM-II riboswitch binds its ligand through a conformational capture mechanism that is dependent on formation of a transient pseudoknot.

The toxin-antitoxin pair MqsR and MqsA are linked to biofilm formation, quorum sensing and motility, but their specific role in these and other cellular processes is unclear. The demonstration that MqsA directly represses transcription of rpoS, encoding the master regulator of the stress response, provides a unifying explanation.

A target-identification strategy based on the yeast three-hybrid system and the SNAP-tag labeling technique identifies new targets for three small-molecule drugs and helps identify a new mechanism for the activity of the anti-inflammatory drug sulfasalazine involving inhibition of sepiapterin reductase.

Heat causes oligomerization and targeting of the ER-based calcium sensor STIM1 to ER–plasma membrane junctions but prevents the functional coupling between STIM1 and the calcium-permeable Orai1 ion channel, resulting in a unique heat off-response of calcium entry.

Synthesis of new vancomycin-like glycopeptides offers opportunities to overcome antibiotic resistance. The crystallographic identification of a reaction intermediate close to the surface of a glycopeptide tailoring enzyme leads to a new biocatalytic strategy to create two classes of teicoplanin analogs.

Cannabis-induced analgesia results from potentiation of the α1 and α3 glycine receptors via a specific interaction with a transmembrane segment of the receptors, and this distinguishes the analgesic effects from the psychoactive effects of cannabinoids.

Going against the classical model of β-arrestin–mediated internalization and downregulation of GPCRs, FRET, FRAP and time-lapse imaging show that PTHR remains active when bound to β-arrestin and is ultimately terminated by retromer complex, a complex involved in transport from endosomes to the Golgi.

Mutant p53 can attenuate the function of wild-type p53, p63 and p73. An aggregation-nucleating sequence in p53 that is revealed in structurally destabilized mutants can induce coaggregation with p63 and p73, resulting in their sequestration in cellular inclusions.

Metabolic engineering often involves the addition of enzymes, redirection of metabolic flux or elimination of undesirable endpoints and thus requires laborious optimization of numerous parameters. A new method to derive 'blueprints' from real-time measurements of metabolic networks significantly accelerates this process as demonstrated with the production of dihydroxyacetone phosphate.

Magic-angle spinning ssNMR used to monitor the E. coli integral membrane protein DGK reconstituted into lipid bilayers reveals the kinetics and mechanisms of this enzyme in both the membrane phase where diacylglycerol is converted to PA and in the aqueous phase where ATP is converted to ADP.

A screen for compounds that alter fat content in C. elegans identifies a novel agonist of an AMP-activated kinase pathway that reduces fat storage as well as implicates the transcription factor K08F8.2 as a regulator of fat metabolism.

Hydrogenases can generate hydrogen gas, but oxygen sensitivity often limits their practical applications. Investigations of an oxygen-tolerant [NiFe] hydrogenase now show that an unusual FeS cluster with six cysteine ligands alters the electron pathway to reduce unwanted oxygen and maintain enzyme function.

The use of synthetic analogs to explore substrate promiscuity during trehalose incorporation into the mycobacterial cell wall yields a fluorescent probe that can be used to examine M. tuberculosis cell biology and detect this harmful pathogen within macrophages.

As metabolic reactions are often in equilibrium, product sequestration is often used to drive engineered pathways forward. For n-butanol, however, this is not possible; instead, introducing kinetic barriers for backwards reactions significantly increases product yield.

NMR reveals the dynamic stretching ability of the subdomain LH of the intrinsically disordered p21, providing a physical basis for the binding and functional diversity in its cell cycle regulatory role as a modulator of Cdk–cyclin complexes.

RNase T is a 3′-to-5′ exonuclease involved in RNA maturation pathways. Biochemical and three-dimensional structures of RNase T in complex with single- or double-stranded DNA reveal mechanisms of substrate selection and catalysis by this nuclease.