Characterization of the Preprocessed Copper Site Equilibrium in Amine Oxidase and Assignment of the Reactive Copper Site in Topaquinone Biogenesis.

Copper-dependent amine oxidases produce their redox active cofactor, 2,4,5-trihydroxyphenylalanine quinone (TPQ), via the CuII-catalyzed oxygenation of an active site tyrosine. This study addresses possible mechanisms for this biogenesis process by presenting the geometric and electronic structure characterization of the CuII-bound, prebiogenesis (preprocessed) active site of the enzyme Arthrobacter globiformis amine oxidase (AGAO). CuII-loading into the preprocessed AGAO active site is slow ( kobs = 0.13 h-1), and is preceded by CuII binding in a separate kinetically favored site that is distinct from the active site. Preprocessed active site CuII is in a thermal equilibrium between two species, an entropically favored form with tyrosine protonated and unbound from the CuII site, and an enthalpically favored form with tyrosine bound deprotonated to the CuII active site. It is shown that the CuII-tyrosinate bound form is directly active in biogenesis. The electronic structure determined for the reactive form of the preprocessed CuII active site is inconsistent with a biogenesis pathway that proceeds through a CuI-tyrosyl radical intermediate, but consistent with a pathway that overcomes the spin forbidden reaction of 3O2 with the bound singlet substrate via a three-electron concerted charge-transfer mechanism.

Formation of a Copper(II)-Tyrosyl Complex at the Active Site of Lytic Polysaccharide Monooxygenases Following Oxidation by H2O2.

Hydrogen peroxide is a cosubstrate for the oxidative cleavage of saccharidic substrates by copper-containing lytic polysaccharide monooxygenases (LPMOs). The rate of reaction of LPMOs with hydrogen peroxide is high, but it is accompanied by rapid inactivation of the enzymes, presumably through protein oxidation. Herein, we use UV-vis, CD, XAS, EPR, VT/VH-MCD, and resonance Raman spectroscopies, augmented with mass spectrometry and DFT calculations, to show that the product of reaction of an AA9 LPMO with H2O2 at higher pHs is a singlet Cu(II)-tyrosyl radical species, which is inactive for the oxidation of saccharidic substrates. The Cu(II)-tyrosyl radical center entails the formation of significant Cu(II)-(●OTyr) overlap, which in turn requires that the plane of the d(x2-y2) SOMO of the Cu(II) is orientated toward the tyrosyl radical. We propose from the Marcus cross-relation that the active site tyrosine is part of a "hole-hopping" charge-transfer mechanism formed of a pathway of conserved tyrosine and tryptophan residues, which can protect the protein active site from inactivation during uncoupled turnover.

The molecular basis of polysaccharide cleavage by lytic polysaccharide monooxygenases.

Lytic polysaccharide monooxygenases (LPMOs) are copper-containing enzymes that oxidatively break down recalcitrant polysaccharides such as cellulose and chitin. Since their discovery, LPMOs have become integral factors in the industrial utilization of biomass, especially in the sustainable generation of cellulosic bioethanol. We report here a structural determination of an LPMO-oligosaccharide complex, yielding detailed insights into the mechanism of action of these enzymes. Using a combination of structure and electron paramagnetic resonance spectroscopy, we reveal the means by which LPMOs interact with saccharide substrates. We further uncover electronic and structural features of the enzyme active site, showing how LPMOs orchestrate the reaction of oxygen with polysaccharide chains.

Spectroscopic Definition of the CuZ° Intermediate in Turnover of Nitrous Oxide Reductase and Molecular Insight into the Catalytic Mechanism.

Spectroscopic methods and density functional theory (DFT) calculations are used to determine the geometric and electronic structure of CuZ°, an intermediate form of the Cu4S active site of nitrous oxide reductase (N2OR) that is observed in single turnover of fully reduced N2OR with N2O. Electron paramagnetic resonance (EPR), absorption, and magnetic circular dichroism (MCD) spectroscopies show that CuZ° is a 1-hole (i.e., 3CuICuII) state with spin density delocalized evenly over CuI and CuIV. Resonance Raman spectroscopy shows two Cu-S vibrations at 425 and 413 cm-1, the latter with a -3 cm-1 O18 solvent isotope shift. DFT calculations correlated to these spectral features show that CuZ° has a terminal hydroxide ligand coordinated to CuIV, stabilized by a hydrogen bond to a nearby lysine residue. CuZ° can be reduced via electron transfer from CuA using a physiologically relevant reductant. We obtain a lower limit on the rate of this intramolecular electron transfer (IET) that is >104 faster than the unobserved IET in the resting state, showing that CuZ° is the catalytically relevant oxidized form of N2OR. Terminal hydroxide coordination to CuIV in the CuZ° intermediate yields insight into the nature of N2O binding and reduction, specifying a molecular mechanism in which N2O coordinates in a µ-1,3 fashion to the fully reduced state, with hydrogen bonding from Lys397, and two electrons are transferred from the fully reduced µ4S2- bridged tetranuclear copper cluster to N2O via a single Cu atom to accomplish N-O bond cleavage.

Determination of the active form of the tetranuclear copper sulfur cluster in nitrous oxide reductase.

N2OR has been found to have two structural forms of its tetranuclear copper active site, the 4CuS Cu(Z)* form and the 4Cu2S Cu(Z) form. EPR, resonance Raman, and MCD spectroscopies have been used to determine the redox states of these sites under different reductant conditions, showing that the Cu(Z)* site accesses the 1-hole and fully reduced redox states, while the Cu(Z) site accesses the 2-hole and 1-hole redox states. Single-turnover reactions of N2OR for Cu(Z) and Cu(Z)* poised in these redox states and steady-state turnover assays with different proportions of Cu(Z) and Cu(Z)* show that only fully reduced Cu(Z)* is catalytically competent in rapid turnover with N2O.

Advancing primary care: Establishing family medicine specialty in Tanzania.

Family medicine has existed as a training pathway through a private university in Tanzania since 2004. As global calls have increased to embrace primary health care as a pathway to ensuring universal health coverage, so has Tanzania recently turned to explore family medicine as a specialty to improve access to comprehensive, high-quality healthcare for her entire population. This article outlines ongoing efforts to define competencies and skills of a family medicine physician in Tanzania, engage government support and open the first public university training programme for family medicine postgraduate education.

A pragmatic approach to equitable global health partnerships in academic health sciences.

Global partnerships offer opportunities for academic departments in the health sciences to achieve mutual benefits. However, they are often challenged by inequities in power, privilege and finances between partners that have plagued the discipline of global health since its founding. In this article, a group of global health practitioners in academic medicine offer a pragmatic framework and practical examples for designing more ethical, equitable and effective collaborative global relationships between academic health science departments, building on the principles laid out by the coalition Advocacy for Global Health Partnerships in the Brocher declaration.

Building the foundation for universal healthcare: Academic family medicine's ability to train family medicine practitioners to meet the needs of their community across the globe.

BACKGROUND:  The Declaration of Astana marked a revived global interest in investing in primary care as a means to achieve universal healthcare. Family medicine clinicians are uniquely trained to provide high-quality, comprehensive primary care throughout the lifespan. Yet little focus has been placed on understanding the needs of family medicine training programs. AIM:  This study aims to assess broad patterns of strengths and resource challenges faced by academic programs that train family medicine clinicians. METHODS:  An anonymous online survey was sent to family medicine faculty using World Organization of Family Doctors (WONCA) listservs. RESULTS:  Twenty-nine representatives of academic family medicine programs from around the globe answered the survey. Respondents cited funding for the program and/or individual trainees as one of either their greatest resources or greatest limitations. Frequently available resources included quality and quantity of faculty and reliable clinical training sites. Frequently noted limitations included recruitment capacity and social capital. Over half of respondents reported their program had at some point faced a disruption or gap in its ability to recruit or train, most often because of loss of government recognition. Reflecting on these patterns, respondents expressed strong interest in partnerships focusing on faculty development and research collaboration. LESSONS LEARNT:  This study provides a better understanding of the challenges family medicine training programs face and how to contribute to their sustainability and growth, particularly in terms of areas for investment, opportunities for government policy and action and areas of collaboration.

Development and Implementation of an Antimicrobial Stewardship Checklist in Sub-Saharan Africa: A Co-Creation Consensus Approach.

Antimicrobial stewardship (AMS) initiatives promote the responsible use of antimicrobials in healthcare settings as a key measure to curb the global threat of antimicrobial resistance (AMR). Defining the core elements of AMS is essential for developing and evaluating comprehensive AMS programmes. This project used co-creation and Delphi consensus procedures to adapt and extend the existing published international AMS checklist. The overall objective was to arrive at a contextualised checklist of core AMS elements and key behaviours for use within healthcare settings in Sub-Saharan Africa, as well as to implement the checklist in health institutions in four African countries. The AMS checklist tool was developed using a modified Delphi approach to achieve local expert consensus on the items to be included on the checklist. Fourteen healthcare/public health professionals from Tanzania, Zambia, Uganda, Ghana and the UK were invited to review, score and comment on items from a published global AMS checklist. Following their feedback, 8 items were rephrased, and 25 new items were added to the checklist. The final AMS checklist tool was deployed across 19 healthcare sites and used to assess AMS programmes before and after an AMS intervention in 14 of the 19 sites. The final tool comprised 54 items. Across the 14 sites, the completed checklists consistently showed improvements for all the AMS components following the intervention. The greatest improvements observed were the presence of formal multidisciplinary AMS structures (79%) and the execution of a point-prevalence survey (72%). The elements with the least improvement were access to laboratory/imaging services (7%) and the presence of adequate financial support for AMS (14%). In addition to capturing the quantitative and qualitative changes associated with the AMS intervention, project evaluation suggested that administering the AMS checklist made unique contributions to ongoing AMS activities. Furthermore, 29 additional AMS activities were reported as a direct result of the prompting checklist questions. Contextualised, co-created AMS tools are necessary for managing antimicrobial use across healthcare settings and increasing local AMS ownership and commitment. This study led to the development of a new AMS checklist, which proved successful in capturing AMS improvements in Tanzania, Zambia, Uganda, and Ghana. The tool also made unique contributions to furthering local AMS efforts. This study extends the existing AMS materials for low- and middle-income countries and provides empirical evidence for successful use in practice.

An Assessment of International Family Medicine Faculty Development Priorities: Perspectives From the American Academy of Family Physicians Global Health Workshop.

INTRODUCTION: The proliferation of new family medicine training programs across the globe has increased the demand for faculty development (FD) opportunities in international settings. US-based faculty may partner with international colleagues to support FD. In 2016, the Society of Teachers of Family Medicine Global Health Educators Collaborative (STFM-GHEC) began to develop a toolkit of low-cost FD resources for this purpose. To ensure that the resources appropriately target current FD needs, STFM-GHEC organized a session at the 2016 American Academy of Family Physicians (AAFP) Global Health Workshop (GHW) to collect feedback from internationally-based and US-based faculty. METHODS: The authors presented a list of faculty development topics to attendees of an AAFP GHW session entitled "Global Faculty Development Tool Kit" on September 8, 2016, in Atlanta, Georgia. Workshop participants voted up to five times each using sticky notes for the topics they felt were of greatest need. RESULTS: Forty-five participants cast 157 votes (34 from internationally-based faculty, 123 from US-based faculty). The combined group ranked curriculum development, program evaluation, and teaching methods as the most important FD needs. Both groups identified assessment strategy and time management among the least important FD needs. Other topics such as technology training and research design varied widely between the two groups in relative importance. CONCLUSIONS: This pilot demonstrates that US-based and internationally-based family medicine faculty may differ in their perceived FD needs. This exercise may be utilized by future members in global health partnerships to understand and prioritize faculty development needs.

The Global Health Service Partnership: An Academic-Clinical Partnership to Build Nursing and Medical Capacity in Africa.

The World Health Organization estimates a global deficit of about 12.9 million skilled health professionals (midwives, nurses, and physicians) by 2035. These shortages limit the ability of countries, particularly resource-constrained countries, to deliver basic health care, to respond to emerging and more complex needs, and to teach, graduate, and retain their future health professionals-a vicious cycle that is perpetuated and has profound implications for health security. The Global Health Service Partnership (GHSP) is a unique collaboration between the Peace Corps, President's Emergency Plan for AIDS Relief, Seed and host-country institutions, which aims to strengthen the breadth and quality of medical and nursing education and care delivery in places with dire shortages of health professionals. Nurse and physician educators are seconded to host institutions to serve as visiting faculty alongside their local colleagues. They serve for 1 year with many staying longer. Educational and clinical best practices are shared, emphasis is placed on integration of theory and practice across the academic-clinical domains and the teaching and learning environment is expanded to include implementation science and dissemination of locally tailored and sustainable practice innovations. In the first 3 years (2013-2016) GHSP placed 97 nurse and physician educators in three countries (Malawi, Tanzania, and Uganda). These educators have taught 454 courses and workshops to 8,321 trainees, faculty members, and practicing health professionals across the curriculum and in myriad specialties. Mixed-methods evaluation included key stakeholder interviews with host institution faculty and students who indicate that the addition of GHSP enhanced clinical teaching (quality and breadth) resulting in improved clinical skills, confidence, and ability to connect theory to practice and critical thinking. The outputs and outcomes from four exemplars which focus on the translation of evidence to practice through implementation science are included. Findings from the first 3 years of GHSP suggest that an innovative, locally tailored and culturally appropriate multi-country academic-clinical partnership program that addresses national health priorities is feasible and generated new knowledge and best practices relevant to capacity building for nursing and medical education. This in turn has implications for improving the health of populations who suffer a disproportionate burden of global disease.

Protonation state of the Cu4S2 CuZ site in nitrous oxide reductase: redox dependence and insight into reactivity.

Spectroscopic and computational methods have been used to determine the protonation state of the edge sulfur ligand in the Cu4S2 CuZ form of the active site of nitrous oxide reductase (N2OR) in its 3CuICuII (1-hole) and 2CuI2CuII (2-hole) redox states. The EPR, absorption, and MCD spectra of 1-hole CuZ indicate that the unpaired spin in this site is evenly delocalized over CuI, CuII, and CuIV. 1-hole CuZ is shown to have a µ2-thiolate edge ligand from the observation of S-H bending modes in the resonance Raman spectrum at 450 and 492 cm-1 that have significant deuterium isotope shifts (-137 cm-1) and are not perturbed up to pH 10. 2-hole CuZ is characterized with absorption and resonance Raman spectroscopies as having two Cu-S stretching vibrations that profile differently. DFT models of the 1-hole and 2-hole CuZ sites are correlated to these spectroscopic features to determine that 2-hole CuZ has a µ2-sulfide edge ligand at neutral pH. The slow two electron (+1 proton) reduction of N2O by 1-hole CuZ is discussed and the possibility of a reaction between 2-hole CuZ and O2 is considered.

Lytic Polysaccharide Monooxygenases in Biomass Conversion.

The derivation of second-generation biofuels from non-edible biomass is viewed as crucial for establishing a sustainable bio-based economy for the future. The inertness of lignocellulosic biomass makes its breakdown for conversion into fuels and other compounds a challenge. Enzyme cocktails can be utilized in the bio-refinery for lignocellulose deconstruction but until recently their costs were regarded as high. Lytic polysaccharide monooxygenases (LPMOs) offer tremendous promise for further process improvements owing to their ability to boost the activity of biomass-degrading enzyme consortia. Combining data from multiple disciplines, progress has been made in understanding the biochemistry of LPMOs. We review the academic literature in this area and highlight some of the key questions that remain.

Structure-function characterization reveals new catalytic diversity in the galactose oxidase and glyoxal oxidase family.

Alcohol oxidases, including carbohydrate oxidases, have a long history of research that has generated fundamental biological understanding and biotechnological applications. Despite a long history of study, the galactose 6-oxidase/glyoxal oxidase family of mononuclear copper-radical oxidases, Auxiliary Activity Family 5 (AA5), is currently represented by only very few characterized members. Here we report the recombinant production and detailed structure-function analyses of two homologues from the phytopathogenic fungi Colletotrichum graminicola and C. gloeosporioides, CgrAlcOx and CglAlcOx, respectively, to explore the wider biocatalytic potential in AA5. EPR spectroscopy and crystallographic analysis confirm a common active-site structure vis-à-vis the archetypal galactose 6-oxidase from Fusarium graminearum. Strikingly, however, CgrAlcOx and CglAlcOx are essentially incapable of oxidizing galactose and galactosides, but instead efficiently catalyse the oxidation of diverse aliphatic alcohols. The results highlight the significant potential of prospecting the evolutionary diversity of AA5 to reveal novel enzyme specificities, thereby informing both biology and applications.