Regulation of Eag1 gating by its intracellular domains.

Voltage-gated potassium channels (Ks) are gated by transmembrane voltage sensors (VS) that move in response to changes in membrane voltage. K10.1 or Eag1 also has three intracellular domains: PAS, C-linker, and CNBHD.

Structure of the voltage-gated K⁺ channel Eag1 reveals an alternative voltage sensing mechanism.

Voltage-gated potassium (K(v)) channels are gated by the movement of the transmembrane voltage sensor, which is coupled, through the helical S4-S5 linker, to the potassium pore. We determined the single-particle cryo-electron microscopy structure of mammalian K(v)10.1, or Eag1, bound to the channel inhibitor calmodulin, at 3.

Structural rearrangements of a polyketide synthase module during its catalytic cycle.

The polyketide synthase (PKS) mega-enzyme assembly line uses a modular architecture to synthesize diverse and bioactive natural products that often constitute the core structures or complete chemical entities for many clinically approved therapeutic agents. The architecture of a full-length PKS module from the pikromycin pathway of Streptomyces venezuelae creates a reaction chamber for the intramodule acyl carrier protein (ACP) domain that carries building blocks and intermediates between acyltransferase, ketosynthase and ketoreductase active sites (see accompanying paper). Here we determine electron cryo-microscopy structures of a full-length pikromycin PKS module in three key biochemical states of its catalytic cycle.

Structure of a modular polyketide synthase.

Polyketide natural products constitute a broad class of compounds with diverse structural features and biological activities. Their biosynthetic machinery, represented by type I polyketide synthases (PKSs), has an architecture in which successive modules catalyse two-carbon linear extensions and keto-group processing reactions on intermediates covalently tethered to carrier domains. Here we used electron cryo-microscopy to determine sub-nanometre-resolution three-dimensional reconstructions of a full-length PKS module from the bacterium Streptomyces venezuelae that revealed an unexpectedly different architecture compared to the homologous dimeric mammalian fatty acid synthase.

The yeast 14-3-3 proteins BMH1 and BMH2 differentially regulate rapamycin-mediated transcription.

14-3-3 proteins are highly conserved and have been found in all eukaryotic organisms investigated. They are involved in many varied cellular processes, and interact with hundreds of other proteins. Among many other roles in cells, yeast 14-3-3 proteins have been implicated in rapamycin-mediated cell signalling.

Cyanobacterial polyketide synthase docking domains: a tool for engineering natural product biosynthesis.

Modular type I polyketide synthases (PKSs) are versatile biosynthetic systems that initiate, successively elongate, and modify acyl chains. Intermediate transfer between modules is mediated via docking domains, which are attractive targets for PKS pathway engineering to produce natural product analogs. We identified a class 2 docking domain in cyanobacterial PKSs and determined crystal structures for two docking domain pairs, revealing a distinct class 2 docking strategy for promoting intermediate transfer.

Structure and function of the RedJ protein, a thioesterase from the prodiginine biosynthetic pathway in Streptomyces coelicolor.

Prodiginines are a class of red-pigmented natural products with immunosuppressant, anticancer, and antimalarial activities. Recent studies on prodiginine biosynthesis in Streptomyces coelicolor have elucidated the function of many enzymes within the pathway. However, the function of RedJ, which was predicted to be an editing thioesterase based on sequence similarity, is unknown.

Disruption of the proton relay network in the class 2 dihydroorotate dehydrogenase from Escherichia coli.

Dihydroorotate dehydrogenases (DHODs) are FMN-containing enzymes that catalyze the conversion of dihydroorotate (DHO) to orotate in the de novo synthesis of pyrimidines. During the reaction, a proton is transferred from C5 of DHO to an active site base and the hydrogen at C6 of DHO is transferred to N5 of the isoalloxazine ring of the flavin as a hydride. In class 2 DHODs, a hydrogen bond network observed in crystal structures has been proposed to deprotonate the C5 atom of DHO.