The CotA laccase from the endospore coat of Bacillus subtilis has been crystallized in the presence of the noncatalytic co-oxidant 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS), and the structure was determined using synchrotron radiation. The binding site for this adduct is well defined and indicates how ABTS, in conjunction with laccases, could act as an oxidative mediator toward non-phenolic moieties. In addition, a dioxygen moiety is clearly defined within the solvent channel oriented toward one of the T3 copper atoms in the trinuclear center.Laccases (benzenediol oxygen oxidoreductase; EC 1.10.3.2) belong to the multi-copper oxidase family of enzymes that includes ascorbate oxidase (L-ascorbate oxygen oxidoreductase; EC 1.10.3.3) and ceruloplasmin (Fe(II) oxygen oxidoreductase; EC 1.16.3.1); for recent reviews, see Refs. 1 and 2). X-ray structural studies over the past decade have enabled the elucidation of a significant number of structural and functional aspects of these enzymes, but many key questions still remain. Two of these involve the mechanism of electron transfer from substrates and the mechanism of dioxygen reduction (2, 3). Laccases are the simplest representatives of the family and are therefore used as model systems for investigating structurefunction relationships in the multi-copper oxidases. Such fundamental studies are aimed at clarifying the molecular basis for the enzyme redox potential and the specificity toward different substrates.Most of the known laccases have fungal (e.g. white-rot fungi) or plant origins, although a few laccases have recently been identified and isolated in bacteria (4 -6). These enzymes have been implicated in many diverse physiological functions such as morphogenesis, pathogenesis, lignin synthesis, and lignolysis (4, 7). Chemically, all these functions are related to the oxidation of a range of aromatic substrates such as polyphenols, methoxy-substituted phenols, diamines, and even some inorganic compounds. The one-electron oxidation of these reducing substrates occurs concomitantly with a four-electron reduction of molecular dioxygen to water. The catalytic centers consist of three structurally and functionally distinct copper centers. T1 copper ("blue copper") is a mononuclear center involved in substrate oxidation, whereas T2 and T3 form a trinuclear center involved in dioxygen reduction to water; for a definition of the copper types, see Ref. 8. The initial substrate reaction products are dioxygen-centered radicals or cation radicals, which usually react further through non-enzymatic routes for the oxidative coupling of monomers or the degradation of polymers.Because of their high relative nonspecific oxidation capacity, laccases have been found to be useful biocatalysts for diverse biotechnological applications (9). Their biotechnological importance showed a marked increased after the discovery that the oxidizing reaction substrate range could be further extended in the presence of the so-called mediators, small readily oxidizable molecules (10)...

Klebsiella pneumoniae is a nosocomial pathogen frequently isolated from opportunistic infections, especially in clinical environments. In spite of its potential pathogenicity, this microorganism has several metabolic potentials that could be used in biotechnology applications. K. pneumoniae is able to metabolize glycerol as a sole source of carbon and energy. 1,3-Propanediol dehydrogenase is the core of the metabolic pathway for the use of glycerol. We have determined the crystallographic structure of 1,3-propanediol dehydrogenase, a type III Fe-NAD-dependent alcohol dehydrogenase, at 2.7-Å resolution. The structure of the enzyme monomer is closely related to that of other alcohol dehydrogenases. The overall arrangement of the enzyme showed a decameric structure, formed by a pentamer of dimers, which is the catalytic form of the enzyme. Dimers are associated by strong ionic interactions that are responsible for the highly stable in vivo packing of the enzyme. Kinetic properties of the enzyme as determined in the article would suggest that this decameric arrangement is related to the cooperativity between monomers.

A study of a project on science stand-up comedy developed in Portugal between 2009 and 2013 is presented, in which thirteen scientists, coordinated by a science communicator and a professional actor, created and presented comedy acts. Eleven of these scientists were asked about their motivations to participate, the process of performance development and the perceived value of the project. Personal motivations were highly important, but professional reasons were also mentioned. Working in a group with the guidance of coordinators, testing and re-writing the texts and gradually gaining confidence on stage were considered fundamental in the development of the shows. Additionally, a questionnaire revealed that the audience, most of whom were young adults, and held a higher education degree, were satisfied with the show. Overall, both participating scientists and audience members considered that stand-up comedy has potential for science communication.

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The sorbitol operon regulator (SorC) regulates the metabolism of L-sorbose in Klebsiella pneumonia. SorC was overexpressed in Escherichia coli and purified, and crystals were obtained of a tetrameric form. A single crystal showed X-ray diffraction to 3.20 A. The crystal belongs to space group P2(1)2(1)2(1), with unit-cell parameters a = 91.6, b = 113.3, c = 184.1 A. Analysis of the molecular-replacement solution indicates the presence of four SorC molecules in the asymmetric unit.