Cofactor engineering for enhancing the flux of metabolic pathways.

The manufacture of a diverse array of chemicals is now possible with biologically engineered strains, an approach that is greatly facilitated by the emergence of synthetic biology. This is principally achieved through pathway engineering in which enzyme activities are coordinated within a genetically amenable host to generate the product of interest. A great deal of attention is typically given to the quantitative levels of the enzymes with little regard to their overall qualitative states. This highly constrained approach fails to consider other factors that may be necessary for enzyme functionality. In particular, enzymes with physically bound cofactors, otherwise known as holoenzymes, require careful evaluation. Herein, we discuss the importance of cofactors for biocatalytic processes and show with empirical examples why the synthesis and integration of cofactors for the formation of holoenzymes warrant a great deal of attention within the context of pathway engineering

Southern Ocean albedo, inter-hemispheric energy transports and the double ITCZ: global impacts of biases in a coupled model

A causal link has been invoked between inter-hemispheric albedo, cross-equatorial energy transport and the double-IntertropicalConvergence Zone (ITCZ) bias in climate models. Southern Ocean cloud biases are a major determinant of inter-hemispheric albedo biases in many models, including HadGEM2-ES, a fully coupled model with a dynamical ocean. In this study, targeted albedo corrections are applied to explore the dynamical response to artificially reducing these biases. The Southern Hemisphere jet increases in strength in response to the increased tropical-extratropical temperature gradient, with increased energy transport into the mid-latitudes in the atmosphere, but no improvement is observed in the double-ITCZ bias or atmospheric cross-equatorial energy transport. The majority of the adjustment in energy transport in the tropics is achieved in the ocean, with the response further limited to the Pacific Ocean. As a result, the frequently argued teleconnection between the Southern Ocean and tropical precipitation biases is muted. Further experiments in which tropical longwave biases are also reduced do not yield improvement in the representation of the tropical atmosphere. These results suggest that the dramatic improvements in tropical precipitation that have been shown in previous studies may be a function of the lack of dynamical ocean and/or the simplified hemispheric albedo bias corrections applied in that work. It further suggests that efforts to correct the double ITCZ problem in coupled models that focus on large-scale energetic controls will prove fruitless without improvements in the representation of atmospheric processes.MKH, MC and JMH were supported by the Natural Environment Research Council/Department for International Development via the Future Climates for Africa (FCFA) funded project ’Improving Model Processes for African Climate’ (IMPALA, NE/M017265/1). JMH and AJ were supported by the Joint UK DECC/Defra Met Office Hadley Centre Climate Programme (GA01101)

Microbial production of 1-octanol: a naturally excreted biofuel with diesel-like properties

The development of sustainable, bio-based technologies to convert solar energy and carbon dioxide into fuels is a grand challenge. A core part of this challenge is to produce a fuel that is compatible with the existing transportation infrastructure. This task is further compounded by the commercial desire to separate the fuel from the biotechnological host. Based on its fuel characteristics, 1-octanol was identified as an attractive metabolic target with diesel-like properties. We therefore engineered a synthetic pathway specifically for the biosynthesis of 1-octanol in Escherichia coli BL21(DE3) by over-expression of three enzymes (thioesterase, carboxylic acid reductase and aldehyde reductase) and one maturation factor (phosphopantetheinyl transferase). Induction of this pathway in a shake flask resulted in 4.4 mg 1-octanol L(-1) h(-1) which exceeded the productivity of previously engineered strains. Furthermore, the majority (73%) of the fatty alcohol was localised within the media without the addition of detergent or solvent overlay. The deletion of acrA reduced the production and excretion of 1-octanol by 3-fold relative to the wild-type, suggesting that the AcrAB-TolC complex may be responsible for the majority of product efflux. This study presents 1-octanol as a potential fuel target that can be synthesised and naturally accumulated within the media using engineered microbes

Radical change and dietary conservatism: Mixing model estimates of human diets along the Inner Asia and China’s mountain corridors

Recent research has demonstrated that a series of mountains from the eastern Iranian Plateau to eastern Kazakhstan and to western China played a significant role in trans-Eurasian exchange during the third and second millennia BC. In close association with these mountain corridors, a number of southwestern Asian cereals, notably free threshing wheat and barley, moved eastward, and broomcorn millet, among other plant foods originating in China, moved westward. In this paper, we apply Bayesian stable isotope mixing models to published and newly obtained isotopic data in order to quantitatively estimate the contribution of different food resources to human diets, and we consider the complexity of human food strategies at both ends of these mountain corridors: southern Kazakhstan and the Hexi Corridor in western China. Our results contrast the rapid adoption of wheat and/or barley in the Hexi Corridor with the gradual, incremental adoption of millet in southern Kazakhstan during the second millennium BC.The authors are grateful to European Research Council, under grant 24964 (FOGLIP), Washington University Deanery Office Grant, American Association of University Women (AAUW), International Center for Advanced Renewable Energy and Sustainability (I-CARES) for financial support. We are thankful to Catherine Kneale and James Rolfe from Cambridge for assistance with isotopic analysis. We are also grateful to Pavel Tarasov for helps to the manuscript; and to Professors Mayke Wagner and Pavel Tarasov and Dr Robert Spengler for organizing the workshop, entitled ‘The Introduction and Intensification of Agriculture in Central Eurasia’, Berlin in 2015

High nuclearity Ni(ii) cages from hydroxamate ligands

The synthesis, structural and magnetic characterisation of a family of Ni(ii) cages built from hydroxamate ligands is presented. Two pentanuclear 12-MCNi(ii)-4 metallacrowns [Ni5(L1) 4(MeOH)4](ClO4)2·2MeOH (1) and [Ni5(L1)4(py)5](ClO 4)2·H2O (2) (where L1H 2 = 2-(dimethylamino)phenylhydroxamic acid) share analogous, near-planar {Ni5(L1)4}2+ cores, but differ in the number and nature of the ligands located at the axial Ni(ii) sites; the addition of pyridine converting square planar Ni(ii) ions to square-based pyramidal and octahedral Ni(ii) ions, introducing extra paramagnetic metal centres which 'switch on' additional magnetic superexchange pathways. Subtle variations in the reaction scheme used to produce complexes 1 and 2 result in both a change of topology and an increase in nuclearity, through isolation of the hepta- and nonametallic complexes [Ni7(L 1H)8(L1)2(H2O) 6](SO4)·15H2O (3), [Ni 9(μ-H2O)2(L2)6(L 2H)4(H2O)2](SO4) ·29H2O (4) and [Ni9(μ-H2O) 2(L2)6(L2H)4(H 2O)2](ClO4)2·2MeOH· 18H2O (5) (where L2H2 = 2-(amino) phenylhydroxamic acid). Complementary dc magnetic susceptibility studies and DFT analysis indicate dominant antiferromagnetic exchange interactions in 1, 2, 4 and 5, but competing ferro- and antiferromagnetic exchange in 3. © the Partner Organisations 2014.EKB would like to thank the EPSRC for funding (SS). GR acknowledges financial support from the Government of India through the Department of Science and Technology (SR/S1/IC-41/2010; SR/NM/NS-1119/2011) and generous computational resources from the Indian Institute of Technology-Bombay. MKS thanks the University Grants Commission for a Junior Research Fellowship.Published versio

The effect of aclidinium bromide on daily respiratory symptoms of COPD, measured using the Evaluating Respiratory Symptoms in COPD (E-RS: COPD) diary: pooled analysis of two 6-month Phase III studies.

BACKGROUND: Reducing the severity of respiratory symptoms is a key goal in the treatment of chronic obstructive pulmonary disease (COPD). We evaluated the effect of aclidinium bromide 400 μg twice daily (BID) on respiratory symptoms, assessed using the Evaluating Respiratory Symptoms in COPD (E-RS(™): COPD) scale (formerly EXACT-RS). METHODS: Data were pooled from the aclidinium 400 μg BID and placebo arms of two 24-week, double-blind, randomized Phase III studies evaluating aclidinium monotherapy (ATTAIN) or combination therapy (AUGMENT COPD I) in patients with moderate to severe airflow obstruction. Patients were stratified by Global initiative for chronic Obstructive Lung Disease (GOLD) Groups A-D. Change from baseline in E-RS scores, proportion of responders (patients achieving pre-defined improvements in E-RS scores), and net benefit (patients who improved minus patients who worsened) were analyzed. RESULTS: Of 1210 patients, 1167 had data available for GOLD classification. Mean (standard deviation) age was 63.2 (8.6) years, 60.7 % were male, and mean post-bronchodilator forced expiratory volume in 1 s was 54.4 % predicted. Compared with placebo, aclidinium 400 μg BID significantly improved RS-Total (2.38 units vs 0.79 units, p < 0.001) and domain scores (all p < 0.001) at Week 24, and doubled the likelihood of being an RS-Total score responder (p < 0.05), irrespective of GOLD group. The net benefit for RS-Total (Overall: 56.9 % vs 19.4 %; A + C: 65.7 % vs 6.3 %; B + D: 56.0 % vs 20.8 %, for aclidinium 400 μg BID and placebo respectively; all p < 0.05) and domain scores (all p < 0.05) was significantly greater with aclidinium compared with placebo, in both GOLD Groups A + C and B + D. CONCLUSIONS: Aclidinium 400 μg BID significantly improved respiratory symptoms regardless of the patients' level of symptoms at baseline. Net treatment benefit was similar in patients with low or high levels of symptoms. TRIAL REGISTRATION: ATTAIN (ClinicalTrials.gov identifier: NCT01001494 ) and AUGMENT COPD I (ClinicalTrials.gov identifier: NCT01437397 )