The exploitation of thermophiles and their enzymes for the construction of multistep enzyme reactions from characterised enzyme parts

Biocatalysis is a field rapidly expanding to meet a demand for green and sustainable chemical processes. As the use of enzymes for synthetic chemistry becomes more common, the construction of multistep enzyme reactions is likely to become more prominent providing excellent cost and productivity benefits. However, the design and optimisation of multistep reactions can be challenging. An enzyme toolbox of well-characterised enzyme parts is critical for the design of novel multistep reactions. Furthermore, while whole-cell biocatalysis offers an excellent platform for multistep reactions, we are limited to the use of mesophilic host organisms such as Escherichia coli. The development of a thermophilic host organism would offer a powerful tool allowing whole-cell biocatalysis at elevated temperatures. This study aimed to investigate the construction of a multistep enzyme reaction from well-characterised enzyme parts, consisting of an esterase, a carboxylic acid reductase and an alcohol dehydrogenase. A novel thermostable esterase Af-Est2 was characterised both biochemically and structurally. The enzyme shows exceptional stability making it attractive for industrial biocatalysis, and features what is likely a structural or regulatory CoA molecule tightly bound near the active site. Five carboxylic acid reductases (CARs) taken from across the known CAR family were thoroughly characterised. Kinetic analysis of these enzymes with various substrates shows they have a broad but similar substrate specificity and that electron rich acids are favoured. The characterisation of these CARs seeks to provide specifications for their use as a biocatalyst. The use of isolated enzymes was investigated as an alternative to whole-cell biocatalysis for the multistep reaction. Additional enzymes for the regeneration of cofactors and removal of by-products were included, resulting in a seven enzyme reaction. Using characterised enzyme parts, a mechanistic mathematical model was constructed to aid in the understanding and optimisation of the reaction, demonstrating the power of this approach. Thermus thermophilus was identified as a promising candidate for use as a thermophilic host organism for whole-cell biocatalysis. Synthetic biology parts including a BioBricks vector, custom ribosome binding sites and characterised promoters were developed for this purpose. The expression of enzymes to complete the multistep enzyme reaction in T. thermophilus was successful, but native T. thermophilus enzymes prevented the biotransformation from being completed. In summary, this work makes a number of contributions to the enzyme toolbox of well-characterised enzymes, and investigates their combination into a multistep enzyme reaction both in vitro and in vivo using a novel thermophilic host organism.BBSRC, GS

Engineering alcohol oxidases for substrate scope and their application in flow and cascade biocatalysis

Alcohol oxidases have significant advantages over alcohol dehydrogenases (ADHs) for biocatalytic oxidation of alcohols: they don’t require addition of (expensive) nicotinamide cofactors (or a recycling system for cofactor regeneration) and the catalytic reaction is irreversible. Although alcohol oxidases generate hydrogen peroxide when they turn over, this issue can be alleviated by addition of catalase, which, not only removes the peroxide, but also creates more oxygen for cofactor regeneration. Alcohol oxidases are perceived to have a limited substrate scope preventing their wider use in synthesis. Thus, we present the engineering of two alcohol oxidases for increased substrate scope, one for the selective oxidation of primary alcohols and one for secondary alcohol oxidation. Please click Additional Files below to see the full abstract

The effect of terminal globular domains on the response of recombinant mini-spidroins to fiber spinning triggers

From Springer Nature via Jisc Publications RouterHistory: received 2020-02-04, accepted 2020-06-11, registration 2020-06-15, pub-electronic 2020-06-30, online 2020-06-30, collection 2020-12Publication status: PublishedFunder: Defence Science and Technology Laboratory; doi: http://dx.doi.org/10.13039/100010418; Grant(s): DSTLX1000101893, DSTLX1000101893, DSTLX1000101893, DSTLX1000101893, DSTLX1000101893Funder: Engineering and Physical Sciences Research Council; doi: http://dx.doi.org/10.13039/501100000266; Grant(s): EP/L014904/1Funder: Biotechnology and Biological Sciences Research Council; doi: http://dx.doi.org/10.13039/501100000268; Grant(s): BB/M017702/1, BB/M017702/1, BB/M017702/1Abstract: Spider silk spidroins consist of long repetitive protein strands, flanked by globular terminal domains. The globular domains are often omitted in recombinant spidroins, but are thought to be essential for the spiders’ natural spinning process. Mimicking this spinning process could be an essential step towards producing strong synthetic spider silk. Here we describe the production of a range of mini-spidroins with both terminal domains, and characterize their response to a number of biomimetic spinning triggers. Our results suggest that mini-spidroins which are able to form protein micelles due to the addition of both terminal domains exhibit shear-thinning, a property which native spidroins also show. Furthermore, our data also suggest that a pH drop alone is insufficient to trigger assembly in a wet-spinning process, and must be combined with salting-out for effective fiber formation. With these insights, we applied these assembly triggers for relatively biomimetic wet spinning. This work adds to the foundation of literature for developing improved biomimetic spinning techniques, which ought to result in synthetic silk that more closely approximates the unique properties of native spider silk

Substituting meat for mycoprotein reduces genotoxicity and increases the abundance of beneficial microbes in the gut: Mycomeat, a randomised crossover control trial

Purpose The high-meat, low-fibre Western diet is strongly associated with colorectal cancer risk. Mycoprotein, produced from Fusarium venanatum, has been sold as a high-fibre alternative to meat for decades. Hitherto, the effects of mycoprotein in the human bowel have not been well considered. Here, we explored the effects of replacing a high red and processed meat intake with mycoprotein on markers of intestinal genotoxicity and gut health. Methods Mycomeat (clinicaltrials.gov NCT03944421) was an investigator-blind, randomised, crossover dietary intervention trial. Twenty healthy male adults were randomised to consume 240 g day−1 red and processed meat for 2 weeks, with crossover to 2 weeks 240 g day−1 mycoprotein, separated by a 4-week washout period. Primary end points were faecal genotoxicity and genotoxins, while secondary end points comprised changes in gut microbiome composition and activity. Results The meat diet increased faecal genotoxicity and nitroso compound excretion, whereas the weight-matched consumption of mycoprotein decreased faecal genotoxicity and nitroso compounds. In addition, meat intake increased the abundance of Oscillobacter and Alistipes, whereas mycoprotein consumption increased Lactobacilli, Roseburia and Akkermansia, as well as the excretion of short chain fatty acids. Conclusion Replacing red and processed meat with the Fusarium-based meat alternative, mycoprotein, significantly reduces faecal genotoxicity and genotoxin excretion and increases the abundance of microbial genera with putative health benefits in the gut. This work demonstrates that mycoprotein may be a beneficial alternative to meat within the context of gut health and colorectal cancer prevention

An engineered cytidine deaminase for biocatalytic production of a key intermediate of the COVID-19 antiviral Molnupiravir

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Talking about human papillomavirus and cancer:protocol for a patient-centred study to develop scripted consultations

Introduction Persistent infection with sexually transmitted, high-risk human papillomavirus (HPV) types is the cause of all cervical cancers and some anogenital and oropharyngeal cancers. HPV is an extremely common asymptomatic infection but little known and poorly understood by the public. Patients with HPV-related cancers have new and challenging information needs due to the complex natural history of HPV and the stigma of sexual transmission. They may ask questions that are outside the remit of the traditional cancer consultation, and there is a lack of guidance on how to counsel them. This study aims to fulfil that need by developing and testing cancer site-specific scripted consultations. Methods and analysis A synthesis of findings generated from previous work, a systematic review of information-based interventions for patients with HPV-related cancers, and interviews with cancer clinicians will provide the evidence base underpinning provisional messages. These will be explored in three phases of face-to-face interviews with 75–90 purposively selected patients recruited in cancer clinics to: (1) select and prioritise the most salient messages, (2) phrase the messages appropriately in plain English and, (3) test their acceptability and usefulness. Phases 1 and 2 will draw on card-sorting methods used in website design. In phase three, we will create cancer site-specific versions of the script and test them using cognitive interviewing techniques. Ethics and dissemination The study has received ethical approval. Findings will be published in a peer-reviewed journal. The final product will be cancer-specific scripted consultations, most likely in the form of a two-sided information sheet with the most important messages to be conveyed in a consultation on one side, and frequently asked questions for later reading on the reverse. However, they will also be appropriate and readily adaptable to web-based uses

Why don't hospital staff activate the rapid response system (RRS)? How frequently is it needed and can the process be improved?

Abstract Background The rapid response system (RRS) is a process of accessing help for health professionals when a patient under their care becomes severely ill. Recent studies and meta-analyses show a reduction in cardiac arrests by a one-third in hospitals that have introduced a rapid response team, although the effect on overall hospital mortality is less clear. It has been suggested that the difficulty in establishing the benefit of the RRS has been due to implementation difficulties and a reluctance of clinical staff to call for additional help. This assertion is supported by the observation that patients continue to have poor outcomes in our institution despite an established RRS being available. In many of these cases, the patient is often unstable for many hours or days without help being sought. These poor outcomes are often discovered in an ad hoc fashion, and the real numbers of patients who may benefit from the RRS is currently unknown. This study has been designed to answer three key questions to improve the RRS: estimate the scope of the problem in terms of numbers of patients requiring activation of the RRS; determine cognitive and socio-cultural barriers to calling the Rapid Response Team; and design and implement solutions to address the effectiveness of the RRS. Methods The extent of the problem will be addressed by establishing the incidence of patients who meet abnormal physiological criteria, as determined from a point prevalence investigation conducted across four hospitals. Follow-up review will determine if these patients subsequently require intensive care unit or critical care intervention. This study will be grounded in both cognitive and socio-cultural theoretical frameworks. The cognitive model of situation awareness will be used to determine psychological barriers to RRS activation, and socio-cultural models of interprofessional practice will be triangulated to inform further investigation. A multi-modal approach will be taken using reviews of clinical notes, structured interviews, and focus groups. Interventions will be designed using a human factors analysis approach. Ongoing surveillance of adverse outcomes and surveys of the safety climate in the clinical areas piloting the interventions will occur before and after implementation

Insights Into the Biogeochemical Cycling of Iron, Nitrate, and Phosphate Across a 5,300 km South Pacific Zonal Section (153°E–150°W)

Iron, phosphate and nitrate are essential nutrients for phytoplankton growth and hence their supply into the surface ocean controls oceanic primary production. Here, we present a GEOTRACES zonal section (GP13; 30-33oS, 153oE-150oW) extending eastwards from Australia to the oligotrophic South Pacific Ocean gyre outlining the concentrations of these key nutrients. Surface dissolved iron concentrations are elevated at >0.4 nmol L-1 near continental Australia (west of 165°E) and decreased eastward to ≤0.2 nmol L-1 (170oW-150oW). The supply of dissolved iron into the upper ocean (<100m) from the atmosphere and vertical diffusivity averaged 11 ±10 nmol m-2 d-1. In the remote South Pacific Ocean (170oW-150oW) atmospherically sourced iron is a significant contributor to the surface dissolved iron pool with average supply contribution of 23 ± 17% (range 3% to 55%). Surface-water nitrate concentrations averaged 5 ±4 nmol L-1 between 170oW and 150oW whilst surface-water phosphate concentrations averaged 58 ±30 nmol L-1. The supply of nitrogen into the upper ocean is primarily from deeper waters (24-1647 μmol m-2 d-1) with atmospheric deposition and nitrogen fixation contributing <1% to the overall flux, in remote South Pacific waters. The deep water N:P ratio averaged 16 ±3 but declined to <1 above the deep chlorophyll maximum (DCM) indicating a high N:P assimilation ratio by phytoplankton leading to almost quantitative removal of nitrate. The supply stoichiometry for iron and nitrogen relative to phosphate at and above the DCM declines eastward leading to two biogeographical provinces: one with diazotroph production and the other without diazotroph production