Structural snapshots of actively translating human ribosomes.

Macromolecular machines, such as the ribosome, undergo large-scale conformational changes during their functional cycles. Although their mode of action is often compared to that of mechanical machines, a crucial difference is that, at the molecular dimension, thermodynamic effects dominate functional cycles, with proteins fluctuating stochastically between functional states defined by energetic minima on an energy landscape. Here, we have used cryo-electron microscopy to image ex-vivo-derived human polysomes as a source of actively translating ribosomes. Multiparticle refinement and 3D variability analysis allowed us to visualize a variety of native translation intermediates. Significantly populated states include not only elongation cycle intermediates in pre- and post-translocational states, but also eEF1A-containing decoding and termination/recycling complexes. Focusing on the post-translocational state, we extended this assessment to the single-residue level, uncovering striking details of ribosome-ligand interactions and identifying both static and functionally important dynamic elements.

COVID-19 health information system assessments in eight European countries: identified gaps, best practices and recommendations.

BACKGROUND: Global threats, such as the coronavirus disease 2019 (COVID-19) pandemic, have highlighted the critical importance of robust and well-functioning health information systems (HIS) in effectively addressing public health emergencies. To enhance the understanding and the functioning of such systems, it is crucial to perform HIS assessments. This article explores key gaps and identifies best practices in the COVID-19 HIS of eight European countries. Furthermore, it provides recommendations to strengthen European systems for better pandemic preparedness. METHODS: Assessments were carried out in eight European countries using an adapted version of the WHO support tool to strengthen HIS and the Joint Action on Health Information assessment tool. The assessments took place between January 2022 and April 2023. RESULTS: Four main themes emerged regarding the gaps and best practices identified in the various HIS: organizational, technical, legal and resources. The results of these assessments show different approaches implemented by countries to improve their HIS and respond to the demands of the pandemic. CONCLUSIONS: It is imperative for countries to draw valuable insights from the COVID-19 pandemic and strengthen their HIS. This involves the adaptation or development of pandemic preparedness plans, strengthening legislative framework for data sharing and privacy protection, promotion of data standards and international definitions and implementation of a unique person identifier. Additionally, countries will have to act in this post-pandemic era and integrate the newly developed systems and innovations into existing structures, maintain and develop trust by citizens through transparent communication and engage in infodemic management and address resource gaps in the workforce.

Has the COVID-19 pandemic changed existing patterns of non-COVID-19 health care utilization? A retrospective analysis of six regions in Europe.

BACKGROUND: Resilience of national health systems in Europe remains a major concern in times of multiple crises and as more evidence is emerging relating to the indirect effects of the COVID-19 pandemic on health care utilization (HCU), resulting from de-prioritization of regular, non-pandemic healthcare services. Most extant studies focus on regional, disease specific or early pandemic HCU creating difficulties in comparing across multiple countries. We provide a comparatively broad definition of HCU across multiple countries, with potential to expand across regions and timeframes. METHODS: Using a cross-country federated research infrastructure (FRI), we examined HCU for acute cardiovascular events, elective surgeries and serious trauma. Aggregated data were used in forecast modelling to identify changes from predicted European age-standardized counts via fitted regressions (2017-19), compared against post-pandemic data. RESULTS: We found that elective surgeries were most affected, universally falling below predicted levels in 2020. For cardiovascular HCU, we found lower-than-expected cases in every region for heart attacks and displayed large sex differences. Serious trauma was the least impacted by the COVID-19 pandemic. CONCLUSION: The strength of this study comes from the use of the European Population Health Information Research Infrastructure's (PHIRI) FRI, allowing for rapid analysis of regional differences to assess indirect impacts of events such as pandemics. There are marked differences in the capacity of services to return to normal in terms of elective surgery; additionally, we found considerable differences between men and women which requires further research on potential sex or gender patterns of HCU during crises.

Non-Hydrolysable Analogues of Cyclic and Branched Condensed Phosphates: Chemistry and Chemical Proteomics.

Studies into the biology of condensed phosphates almost exclusively cover linear polyphosphates. However, there is evidence for the presence of cyclic polyphosphates (metaphosphates) in organisms and for enzymatic digestion of branched phosphates (ultraphosphates) with alkaline phosphatase. Further research of non-linear condensed phosphates in biology would profit from interactome data of such molecules, however, their stability in biological media is limited. Here we present syntheses of modified, non-hydrolysable analogues of cyclic and branched condensed phosphates, called meta- and ultraphosphonates, and their application in a chemical proteomics approach using yeast cell extracts. We identify putative interactors with overlapping hits for structurally related capture compounds underlining the quality of our results. The datasets serve as starting point to study the biological relevance and functions of meta- and ultraphosphates. In addition, we examine the reactivity of meta- and ultraphosphonates with implications for their "hydrolysable" analogues: Efforts to increase the ring-sizes of meta- or cyclic ultraphosphonates revealed a strong preference to form trimetaphosphate-analogue structures by cyclization and/or ring-contraction. Using carbodiimides for condensation, the so far inaccessible dianhydro product of ultraphosphonate, corresponding to P4 O11 2- , was selectively obtained and then ring-opened by different nucleophiles yielding modified cyclic ultraphosphonates.

Intramolecular activity regulation of adhesion GPCRs in light of recent structural and evolutionary information.

The class B2 of GPCRs known as adhesion G protein-coupled receptors (aGPCRs) has come under increasing academic and nonacademic research focus over the past decade due to their physiological importance as mechano-sensors in cell-cell and cell-matrix contexts. A major advance in understanding signal transduction of aGPCRs was achieved by the identification of the so-called Stachel sequence, which acts as an intramolecular agonist at the interface between the N terminus (Nt) and the seven-transmembrane helix domain (7TMD). Distinct extracellular signals received by the Nt are integrated at the Stachel into structural changes of the 7TMD towards an active state conformation. Until recently, little information was available on how the activation process of aGPCRs is realized at the molecular level. In the past three years several structures of the 7TMD plus the Stachel in complex with G proteins have been determined, which provide new insights into the architecture and molecular function of this receptor class. Herein, we review this structural information to extract common and distinct aGPCR features with particular focus on the Stachel binding site within the 7TMD. Our analysis extends the current view of aGPCR activation and exposes similarities and differences not only between diverse aGPCR members, but also compared to other GPCR classes.

Assessing European national health information systems in peer review format: lessons learnt.

BACKGROUND: Systematic assessments of a country's health information system (HIS) help identify strengths and weaknesses and may stimulate actions for improvement. They represent a capacity-building process for the country assessed as well as for the assessor. The joint action on HISs (InfAct) developed a peer-to-peer assessment methodology adapting an established WHO support tool. The aim of this study is to identify lessons learnt and the added value of the InfAct peer assessment for the assessors. METHODS: A qualitative evaluation of the peer HIS assessment was performed based on 12 semi-structured interviews: nine interviews were carried out with assessors from nine participating countries, and three with an observer (present during assessments). The interviews were carried out between May 2019 and January 2020. Interviews were analysed using qualitative content analysis. RESULTS: The interviews revealed the experiences of the assessors mainly occurred in five areas: assessors strengthened their understanding of what a population-based HIS is; they strengthened their understanding of how a HIS operates in different countries; they learnt how to carry out a HIS assessment; they strengthened their organization, communication, negotiation and reporting skills and they strengthened the networks in health information within and between countries. CONCLUSION: Since the assessors are key personnel in their respective national health systems, the impact of the assessment is not limited to the assessor alone but may extend to stakeholders in their country. The deployment of the InfAct HIS peer assessment, anchored in systematic HIS capacity building across European countries, is recommended.

A crisis like no other? Unmet needs in healthcare during the first wave of the COVID-19 crisis in Austria.

BACKGROUND: Many patients experienced restricted access to healthcare during the Coronavirus Disease 2019 (COVID-19) pandemic. This study is among the first to provide systematic evidence on the existence of subjective unmet needs (SUN) in different population groups during the pandemic. METHODS: Using data on individuals aged 20-64 and living in Austria from the AKCOVID survey (June 2020) and the 'European Social Survey' (2015), SUN were compared between 2015 and 2020, either related to the pandemic (fear of infection, provider closed or treatment postponed) or not (barriers related to knowledge, affordability, time and reachability). Multinomial logistic regression models identified determinants of SUN during the pandemic, adjusting for socio-demographics, socio-economic status and self-reported health. RESULTS: Shares of the population with SUN in 2020 substantially exceeded SUN in 2015. Excess unmet needs were mostly attributable to the pandemic. Postponed treatments and closed providers were the most important reasons for SUN in June 2020. Older age groups (50-64 years), inactive and retired people were most likely to report pandemic-related SUN. We did not find socio-economic differences in pandemic-related SUN. CONCLUSIONS: The pandemic resulted in a supply-side shock to healthcare, with vulnerabilities emerging especially among older people, people with poor health and/or people no longer active on the labour market. Further research could focus on health system resilience and the possibilities to improve management of healthcare services during pandemics without widening inequalities while maintaining population health.

Barriers to accessing health care for people with chronic conditions: a qualitative interview study.

BACKGROUND: There is a growing interest in redesigning healthcare systems to increase access to and coordination across care settings for people with chronic conditions. We aim to gain a better understanding of the barriers faced by (1) children with chronic bronchial asthma, (2) adults with non-specific chronic back pain, and (3) older people with pre-existing mental illness/es in Austria's fragmented social health insurance system. METHODS: Using a qualitative design, we conducted semi-structured interviews face-to-face and by telephone with health service providers, researchers, experts by experience (persons with lived/ personal experience, i.e., service users, patient advocates or family members/carers), and employees in public health administration between July and October 2019. The analysis and interpretation of data were guided by Levesque's model of access, a conceptual framework used to evaluate access broadly according to different dimensions of accessibility to care: approachability, acceptability, availability and accommodation, affordability, and appropriateness. RESULTS: The findings from the 25 expert interviews were organised within Levesque's conceptual framework. They highlight a lack of coordination and defined patient pathways, particularly at the onset of the condition, when seeking a diagnosis, and throughout the care process. On the supply side, patterns of poor patient-provider communication, lack of a holistic therapeutic approach, an urban-rural divide, strict separation between social care and the healthcare system and limited consultation time were among the barriers identified. On the demand side, patients' ability to perceive a need and to subsequently seek and reach healthcare services was an important barrier, closely linked to a patient's socio-economic status, health literacy and ability to pay. CONCLUSIONS: While studies on unmet needs suggest a very low level of barriers to accessing health care in the Austrian context, our study highlights potential 'invisible' barriers. Barriers to healthcare access are of concern for patients with chronic conditions, underlining existing findings about the need to improve health services according to patients' specific needs. Research on how to structure timely and integrated care independent of social and economic resources, continuity of care, and significant improvements in patient-centred communication and coordination of care would be paramount.

Reappraisal of a 2-Cm Cut-off Size for the Management of Cystic Pancreatic Neuroendocrine Neoplasms: A Multicenter International Study.

OBJECTIVE: The aim of this study was to characterize an international cohort of resected cystic pancreatic neuroendocrine neoplasms (cPanNENs) and identify preoperative predictors of aggressive behavior. BACKGROUND: The characteristics of cPanNENs are unknown and their clinical management remains unclear. An observational strategy for asymptomatic cPanNENs ≤2 cm has been proposed by recent guidelines, but evidence is scarce and limited to single-institutional series. METHODS: Resected cPanNENs (1995-2017) from 16 institutions worldwide were included. Solid lesions (>50% solid component), functional tumors, and MEN-1 patients were excluded. Aggressiveness was defined as lymph node (LN) involvement, G3 grading, distant metastases, and/or recurrence. RESULTS: Overall, 263 resected cPanNENs were included, among which 177 (63.5%) were >2 cm preoperatively. A preoperative diagnosis of cPanNEN was established in 162 cases (61.6%) and was more frequent when patients underwent endoscopic ultrasound [EUS, odds ratio (OR) 2.69, 95% confidence interval (CI) 1.52-4.77] and somatostatin-receptor imaging (OR 3.681, 95% CI 1.809-7.490), and for those managed in specialized institutions (OR 3.12, 95% CI 1.57-6.21). Forty-one cPanNENs (15.6%) were considered aggressive. In the whole cohort, LN involvement on imaging, age >65 years, preoperative size >2 cm, and pancreatic duct dilation were independently associated with aggressive behavior. In asymptomatic patients, older age and a preoperative size >2 cm remained independently associated with aggressiveness. Only 1 of 61 asymptomatic cPanNENs ≤2 cm displayed an aggressive behavior. CONCLUSIONS: The diagnostic accuracy of cPanNENs is increased by the use of EUS and somatostatin-receptor imaging and is higher in specialized institutions. Preoperative size >2 cm is independently associated with aggressive behavior. Consequently, a watch-and-wait policy for sporadic asymptomatic cPanNENs ≤2 cm seems justified and safe for most patients.

A Little Autonomy Support Goes a Long Way: Daily Autonomy-Supportive Parenting, Child Well-Being, Parental Need Fulfillment, and Change in Child, Family, and Parent Adjustment Across the Adaptation to the COVID-19 Pandemic.

This study examined the effects of daily parental autonomy support on changes in child behavior, family environment, and parental well-being across 3 weeks during the COVID-19 pandemic in Germany. Day-to-day associations among autonomy-supportive parenting, parental need fulfillment, and child well-being were also assessed. Parents (longitudinal N = 469; Mage  = 42.93, SDage  = 6.40) of school children (6-19 years) reported on adjustment measures at two measurement occasions and completed up to 21 daily online questionnaires in the weeks between these assessments. Results from dynamic structural equation models suggested reciprocal positive relations among autonomy-supportive parenting and parental need fulfillment. Daily parental autonomy support, parental need fulfillment, and child well-being partially predicted change in adjustment measures highlighting the central role of daily parenting for children's adjustment during the pandemic.

Change in mental health symptoms during the COVID-19 pandemic: The role of appraisals and daily life experiences.

OBJECTIVE: When confronted with major threats, people often experience decline in well-being. The central purpose of this study was to identify mechanisms underlying change of well-being in times of threat, using the example of the COVID-19 pandemic, with a focus on appraisals of the pandemic and affective states, stress, as well as mindfulness in daily life. METHOD: We conducted a study across 3.5 weeks, including pretest, posttest, and a diary phase in-between. We worked with a sample of 460 adults, pre- and post-test information, as well as 7,189 observations from the diary phase. RESULTS: Results showed that deterioration in mental health symptoms across the duration of the study was associated with (a) change towards less fortunate appraisals of the pandemic and (b), more negative affect and less mindfulness in daily life. Furthermore, appraisals of the pandemic at pretest predicted experiences in daily life, with more negative appraisals of the pandemic predicting more negative affect and stressor occurrence as well as less mindfulness. CONCLUSIONS: These findings speak to the dynamic nature of well-being and appraisals in times of threat, and highlight the role of experiences in daily life in changes in well-being.

Tracking the route of molecular oxygen in O2-tolerant membrane-bound [NiFe] hydrogenase.

[NiFe] hydrogenases catalyze the reversible splitting of H2 into protons and electrons at a deeply buried active site. The catalytic center can be accessed by gas molecules through a hydrophobic tunnel network. While most [NiFe] hydrogenases are inactivated by O2, a small subgroup, including the membrane-bound [NiFe] hydrogenase (MBH) of Ralstonia eutropha, is able to overcome aerobic inactivation by catalytic reduction of O2 to water. This O2 tolerance relies on a special [4Fe3S] cluster that is capable of releasing two electrons upon O2 attack. Here, the O2 accessibility of the MBH gas tunnel network has been probed experimentally using a "soak-and-freeze" derivatization method, accompanied by protein X-ray crystallography and computational studies. This combined approach revealed several sites of O2 molecules within a hydrophobic tunnel network leading, via two tunnel entrances, to the catalytic center of MBH. The corresponding site occupancies were related to the O2 concentrations used for MBH crystal derivatization. The examination of the O2-derivatized data furthermore uncovered two unexpected structural alterations at the [4Fe3S] cluster, which might be related to the O2 tolerance of the enzyme.

Phthalocyanines: An Old Dog Can Still Have New (Photo)Tricks!

Phthalocyanines have enjoyed throughout the years the benefits of being exquisite compounds with many favorable properties arising from the straightforward and diverse possibilities of their structural modulation. Last decades appreciated a steady growth in applications for phthalocyanines, particularly those dependent on their great photophysical properties, now used in several cutting-edge technologies, particularly in photonic applications. Judging by the vivid reports currently provided by many researchers around the world, the spotlight remains assured. This review deals with the use of phthalocyanine molecules in innovative materials in photo-applications. Beyond a comprehensive view on the recent discoveries, a critical review of the most acclaimed/considered reports is the driving force, providing a brief and direct insight on the latest milestones in phthalocyanine photonic-based science.

Intramolecular Proton Transfer Controls Protein Structural Changes in Phytochrome.

Phytochromes are biological photoswitches that interconvert between two parent states (Pr and Pfr). The transformation is initiated by photoisomerization of the tetrapyrrole chromophore, followed by a sequence of chromophore and protein structural changes. In the last step, a phytochrome-specific peptide segment (tongue) undergoes a secondary structure change, which in prokaryotic phytochromes is associated with the (de)activation of the output module. The focus of this work is the Pfr-to-Pr photoconversion of the bathy bacteriophytochrome Agp2 in which Pfr is the thermodynamically stable state. Using spectroscopic techniques, we studied the structural and functional consequences of substituting Arg211, Tyr165, His278, and Phe192 close to the biliverdin (BV) chromophore. In Pfr, substitutions of these residues do not affect the BV structure. The characteristic Pfr properties of bathy phytochromes, including the protonated propionic side chain of ring C (propC) of BV, are preserved. However, replacing Arg211 or Tyr165 blocks the photoconversion in the Meta-F state, prior to the secondary structure transition of the tongue and without deprotonation of propC. The Meta-F state of these variants displays low photochemical activity, but electronic excitation causes ultrafast alterations of the hydrogen bond network surrounding the chromophore. In all variants studied here, thermal back conversion from the photoproducts to Pfr is decelerated but substitution of His278 or Phe192 is not critical for the Pfr-to-Pr photoconversion. These variants do not impair deprotonation of propC or the α-helix/ß-sheet transformation of the tongue during the Meta-F-to-Pr decay. Thus, we conclude that propC deprotonation is essential for restructuring of the tongue.

Molecular architecture of the ribosome-bound Hepatitis C Virus internal ribosomal entry site RNA.

Internal ribosomal entry sites (IRESs) are structured cis-acting RNAs that drive an alternative, cap-independent translation initiation pathway. They are used by many viruses to hijack the translational machinery of the host cell. IRESs facilitate translation initiation by recruiting and actively manipulating the eukaryotic ribosome using only a subset of canonical initiation factor and IRES transacting factors. Here we present cryo-EM reconstructions of the ribosome 80S- and 40S-bound Hepatitis C Virus (HCV) IRES. The presence of four subpopulations for the 80S•HCV IRES complex reveals dynamic conformational modes of the complex. At a global resolution of 3.9 Šfor the most stable complex, a derived atomic model reveals a complex fold of the IRES RNA and molecular details of its interaction with the ribosome. The comparison of obtained structures explains how a modular architecture facilitates mRNA loading and tRNA binding to the P-site. This information provides the structural foundation for understanding the mechanism of HCV IRES RNA-driven translation initiation.

Benchmarking of a checklist for the identification of familial risk for breast and ovarian cancers in a prospective cohort.

The detection of deleterious germline mutations in BRCA1 and BRCA2 considerably influences the clinical management of healthy and diseased carriers. Therefore, the identification of persons at risk who could uptake genetic counseling and testing is pivotal. We developed a checklist with validated criteria to improve the identification, and prospectively evaluate the incidence, of familial cancer history in 5091 breast cancer patients. The rate of 30.4% of patients at high genetic risk underpins the demand for care in risk identification and counseling. The easy-to-use instrument promotes the implementation and dissemination of risk counseling by physicians.

Crystal structure and functional characterization of selenocysteine-containing glutathione peroxidase 4 suggests an alternative mechanism of peroxide reduction.

Glutathione peroxidases (GPX) are anti-oxidative enzymes that reduce organic and inorganic hydroperoxides to the corresponding alcohols at the expense of reduced glutathione. The human genome involves eight GPX genes and five of them encode for selenocysteine-containing enzymes. Among the human GPX-isoforms, GPX4 is unique since it is capable of reducing complex hydroperoxy ester lipids such as hydroperoxy phospholipids and hydroperoxy cholesterolesters. Using a number of genetically modified mouse strains the biological role of GPX4 has comprehensively characterized but the molecular enzymology is less well explored. This lack of knowledge is partly related to the fact that mammalian selenoproteins are not high-level expressed in conventional overexpression systems. To explore the structural and functional properties of human GPX4 we expressed this selenoprotein in a cysteine-auxotrophic E. coli strain using a semi-chemical expression strategy. The recombinant enzyme was purified in mg amounts from the bacterial lysate to electrophoretic homogeneity and characterized with respect to its protein-chemical and enzymatic properties. Its crystal structure was solved at 1.3 Šresolution and the X-ray data indicated a monomeric protein, which contains the catalytic selenium at the redox level of the seleninic acid. These data suggest an alternative reaction mechanism involving three different redox states (selenol, selenenic acid, seleninic acid) of the catalytically active selenocysteine.

Income-rich and wealth-poor? The impact of measures of socio-economic status in the analysis of the distribution of long-term care use among older people.

This article aims to investigate the impact of using 2 measures of socio-economic status on the analysis of how informal care and home care use are distributed among older people living in the community. Using data from the Survey of Health, Ageing and Retirement in Europe for 14 European countries, we estimate differences in corrected concentration indices for use of informal care and home care, using equivalised household net income and equivalised net worth (as a proxy for wealth). We also calculate horizontal inequity indices using both measures of socio-economic status and accounting for differences in need. The findings show that using wealth as a ranking variable results, as a rule, in a less pro-poor inequality of use for both informal and home care. Once differences in need are controlled for (horizontal inequity), wealth still results in a less pro-poor distribution for informal care, in comparison with income, whereas the opposite is observed for home care. Possible explanations for these differences and research and policy implications are discussed.

The predominance of a naive T helper cell subset in the immune response of experimental acute pancreatitis.

INTRODUCTION: In necrotizing acute pancreatitis (NAP), systemic inflammatory response syndrome (SIRS) and the compensatory anti-inflammatory response syndrome (CARS) decide overall outcome and mortality. In patients, low lymphocyte counts were found, but T-helper cells seemed to conversely increase. Our aim was to further categorize T-helper cells within the context of NAP induced SIRS and CARS. METHODS: NAP was induced by injection of sodium-taurocholate into the common bile duct of male BALB/c mice; sham treated animals received saline infusion. The animals were sacrificed at 6, 12, 24 and 48 h later. Lymphocytes from blood, liver and spleen were isolated and examined by flow cytometry. Staining was performed for CD4, CD8, CD19, CD45RB, CD25, CD69, and CD152. CD4+ cells were sorted for their CD45RB expression and sought for gene regulation associated to TH1/TH2 cells by quantitative RT-PCR. RESULTS: In NAP, CD4+ was solely increased in all compartments. CD8+ remained without substantial alterations. CD45RB showed significant expression in RBhigh in T-helper cells, confirmed by the CD45RBhigh/low ratio (Liver, 24 h: NAP 2.2, SHAM 0.6; p < 0.001). CD45RBhigh and -low cells were not associated to patterns of TH1/TH2 expression. In NAP, CCR4 expression was significantly decreased within RBhigh cells (fold change: 0.04, p < 0.05), while TLR6 showed significant overexpression (fold change: 2.36, p < 0.05). CONCLUSION: T-helper cells increase in NAP, leaning towards CD45RBhigh expression. They resemble naive T-cells, in which NAP leads to expression profiles associated with an innate immune response. This suggests new findings in immunological pathomechanisms of NAP.

Vacuolar SNARE protein transmembrane domains serve as nonspecific membrane anchors with unequal roles in lipid mixing.

Membrane fusion is induced by SNARE complexes that are anchored in both fusion partners. SNAREs zipper up from the N to C terminus bringing the two membranes into close apposition. Their transmembrane domains (TMDs) might be mere anchoring devices, deforming bilayers by mechanical force. Structural studies suggested that TMDs might also perturb lipid structure by undergoing conformational transitions or by zipping up into the bilayer. Here, we tested this latter hypothesis, which predicts that the activity of SNAREs should depend on the primary sequence of their TMDs. We replaced the TMDs of all vacuolar SNAREs (Nyv1, Vam3, and Vti1) by a lipid anchor, by a TMD from a protein unrelated to the membrane fusion machinery, or by artificial leucine-valine sequences. Individual exchange of the native SNARE TMDs against an unrelated transmembrane anchor or an artificial leucine-valine sequence yielded normal fusion activities. Fusion activity was also preserved upon pairwise exchange of the TMDs against unrelated peptides, which eliminates the possibility for specific TMD-TMD interactions. Thus, a specific primary sequence or zippering beyond the SNARE domains is not a prerequisite for fusion. Lipid-anchored Vti1 was fully active, and lipid-anchored Nyv1 permitted the reaction to proceed up to hemifusion, and lipid-anchored Vam3 interfered already before hemifusion. The unequal contribution of proteinaceous TMDs on Vam3 and Nyv1 suggests that Q- and R-SNAREs might make different contributions to the hemifusion intermediate and the opening of the fusion pore. Furthermore, our data support the view that SNARE TMDs serve as nonspecific membrane anchors in vacuole fusion.