Direct α-Hydroxy Acid Loading onto a Bacterial Thiotemplate Assembly Line via a Multienzyme Gateway.

Various nonribosomal peptide synthetases (NRPSs) create structural and functional diversity by incorporating α-hydroxy acids into peptide backbones. Trigonic acid, an unusual cyclopropanol-substituted hydroxy acid, is the source of the molecular warhead of malleicyprol, a critical virulence factor of human and animal pathogens of the Burkholderia pseudomallei (BP) group. The process of selecting and loading this building block remained enigmatic as the NRPS module designated for this task is incomplete. Using a combination of bioinformatics, mutational analyses, targeted metabolomics, and in vitro biochemical assays, we show that two trans-acting enzymes are required to load this central building block onto the modular assembly line. An adenylation-thiolation didomain enzyme (BurJ) activates trigonic acid, followed by the translocation of the enzyme-bound α-hydroxy acid thioester by an FkbH-like protein with a mutated phosphatase domain (BurH). This specialized gateway is the first reported direct loading of an α-hydroxy acid onto a bona fide NRPS module in bacteria and expands the synthetic biology toolbox for the site-specific incorporation of non-canonical building blocks. Moreover, insight into the biochemical basis of virulence factor biosynthesis can provide a foundation for developing enzyme inhibitors as anti-virulence therapeutics against BP pathogen infections.

Trapping of a Polyketide Synthase Module after C-C Bond Formation Reveals Transient Acyl Carrier Domain Interactions.

Modular polyketide synthases (PKSs) are giant assembly lines that produce an impressive range of biologically active compounds. However, our understanding of the structural dynamics of these megasynthases, specifically the delivery of acyl carrier protein (ACP)-bound building blocks to the catalytic site of the ketosynthase (KS) domain, remains severely limited. Using a multipronged structural approach, we report details of the inter-domain interactions after C-C bond formation in a chain-branching module of the rhizoxin PKS. Mechanism-based crosslinking of an engineered module was achieved using a synthetic substrate surrogate that serves as a Michael acceptor. The crosslinked protein allowed us to identify an asymmetric state of the dimeric protein complex upon C-C bond formation by cryo-electron microscopy (cryo-EM). The possible existence of two ACP binding sites, one of them a potential "parking position" for substrate loading, was also indicated by AlphaFold2 predictions. NMR spectroscopy showed that a transient complex is formed in solution, independent of the linker domains, and photochemical crosslinking/mass spectrometry of the standalone domains allowed us to pinpoint the interdomain interaction sites. The structural insights into a branching PKS module arrested after C-C bond formation allows a better understanding of domain dynamics and provides valuable information for the rational design of modular assembly lines.

Remote interpreting in primary care settings: a feasibility trial in Germany.

BACKGROUND: Global migration trends have led to a more diverse population in health care services everywhere, which in turn has set off a paradigm shift away from medical paternalism toward more patient autonomy. Consequently, physicians need to provide a more precise patient-centred healthcare. Professional interpreting appears to play a crucial part in tackling the challenges of language barriers adequately. The aim of this study was to conduct process evaluation through the implementing of video remote interpreting (VR) and telephone remote interpreting (TR) within primary care facilities in the northern German metropolis of Hamburg. METHODS: We conducted a three-armed exploratory pilot trial, which compared VR to TR and to a control group (CG) in different primary care settings. We assessed feasibility of implementation, as well as the acceptance of interpreting tools among their users. In addition, we compared the quality of communication as perceived by patients and physicians, as well as the enabling of patient-centred medicine over all three study groups using quantitative questionnaires. RESULTS: 13 practices (7 GPs, 3 Gynaecologists, 3 Paediatricians) took part in this trial. 183 interpreting calls were documented, 178 physicians as well as 127 patients answered their respective questionnaires. The implementation of the VR- und TR-tools went smoothly and they were broadly accepted by their users. However, the tools were used significantly less often than we had anticipated. With regards to quantitative questionnaires, VR scored significantly better than the control group in terms of the perceived quality of communication by both, patients and physicians and enabled of patient-centred medicine. CONCLUSION: Our main findings were the discrepancy between the assumed high demand of professional interpreting solutions on the one hand and the low willingness of practices to participate on the other. The rather low utilisation rates were also noteworthy. This discrepancy indicates a lack of awareness concerning the adverse effects of using informal or no interpreter in medical settings, which needs to be rectified. Due to the small sample size, all statistical results must be viewed with caution. However, our results show that remote interpreting represents a promising approach to tackling language barriers in primary care settings.

Experiences with remote interpreting tools in primary care settings: a qualitative evaluation of the implementation and usage of remote interpreting tools during a feasibility trial in Germany.

OBJECTIVE: This study aims to evaluate the usage and implementation of video remote (VR) interpreting and telephone remote (TR) interpreting in primary healthcare settings. DESIGN: This publication forms part of a larger three-pronged study in which we compared both remote interpreting modalities to each other and to a control group. This paper conveys the findings of the qualitative evaluation of the implementation and usage of both remote interpreting solutions. The quantitative evaluation of the 6-month intervention period (September 2018-February 2019) has been reported previously. After this period, we conducted focus groups with the healthcare professionals involved. The focus groups were recorded, transcribed verbatim and analysed using the structured qualitative content analysis. SETTING: We provided either VR or TR tools to 10 different primary healthcare practices (general medicine, gynaecology and paediatrics) in the city of Hamburg, Germany. PARTICIPANTS: Three physicians and two physician's assistants took part in the TR focus group. The VR focus group consisted of four physicians. RESULTS: The main topics identified were the importance of communication for diagnostic and therapeutic processes, previous solutions to language barriers, as well as advantages and disadvantages of the two remote interpreting solutions. Advantages included the possibility to adequately communicate with language discordant patients and the high quality of the interpreting. Disadvantages included the habituation time required for new technology as well as time constraints. CONCLUSION: Our evaluation found that these solutions were highly appreciated, if not considered indispensable, for the delivery of appropriate medical care to language-discordant patients. Differences between the two modalities were named and concrete suggestions for improvement were made. Policy-makers should consider providing VR or TR as an adequate and safe interpreting service alternative when professional in-person interpreters are not available or too expensive.

Bacterial Pathogen Channels Medium-Sized Fatty Acids into Malleicyprol Biosynthesis.

Bacterial pathogens of the Burkholderia pseudomallei (BP) group cause life-threatening infections in both humans and animals. Critical for the virulence of these often antibiotic-resistant pathogens is the polyketide hybrid metabolite malleicyprol, which features two chains, a short cyclopropanol-substituted chain and a long hydrophobic alkyl chain. The biosynthetic origin of the latter has remained unknown. Here, we report the discovery of novel overlooked malleicyprol congeners with varied chain lengths and identify medium-sized fatty acids as polyketide synthase (PKS) starter units that constitute the hydrophobic carbon tails. Mutational and biochemical analyses show that a designated coenzyme A-independent fatty acyl-adenylate ligase (FAAL, BurM) is essential for recruiting and activating fatty acids in malleicyprol biosynthesis. In vitro reconstitution of the BurM-catalyzed PKS priming reaction and analysis of ACP-bound building blocks reveal a key role of BurM in the toxin assembly. Insights into the function and role of BurM hold promise for the development of enzyme inhibitors as novel antivirulence therapeutics to combat infections with BP pathogens.

Rational Design of Flavonoid Production Routes Using Combinatorial and Precursor-Directed Biosynthesis.

Combinatorial biosynthesis has great potential for designing synthetic circuits and amplifying the production of new active compounds. Studies on multienzyme cascades are extremely useful for improving our knowledge on enzymatic catalysis. In particular, the elucidation of enzyme substrate promiscuity can be potentially used for bioretrosynthetic approaches, leading to the design of alternative and more convenient routes to produce relevant molecules. In this perspective, plant-derived polyketides are extremely adaptable to those synthetic biological applications. Here, we present a combination of an in vitro CoA ligase activity assay coupled with a bacterial multigene expression system that leads to precursor-directed biosynthesis of 21 flavonoid derivatives. When the vast knowledge from protein databases is exploited, the herein presented procedure can be easily repeated with additional plant-derived polyketides. Lastly, we report an efficient in vivo expression system that can be further exploited to heterologously express pathways not necessarily related to plant polyketide synthases.