Probing the Structure of [NiFeSe] Hydrogenase with QM/MM Computations

The geometry and vibrational behavior of selenocysteine [NiFeSe] hydrogenase isolated from Desulfovibrio vulgaris Hildenborough have been investigated using a hybrid quantum mechanical (QM)/ molecular mechanical (MM) approach. Structural models have been built based on the three conformers identified in the recent crystal structure resolved at 1.3 Å from X-ray crystallography. In the models, a diamagnetic Ni2+ atom was modeled in combination with both Fe2+ and Fe3+ to investigate the effect of iron oxidation on geometry and vibrational frequency of the nonproteic ligands, CO and CN-, coordinated to the Fe atom. Overall, the QM/MM optimized geometries are in good agreement with the experimentally resolved geometries. Analysis of computed vibrational frequencies, in comparison with experimental Fourier-transform infrared (FTIR) frequencies, suggests that a mixture of conformers as well as Fe2+ and Fe3+ oxidation states may be responsible for the acquired vibrational spectra.DFG, 390540038, EXC 2008: UniSysCatDFG, 414044773, Open Access Publizieren 2019 - 2020 / Technische Universität BerlinEC/H2020/810856/EU/Twin to Illuminate Metals in Biology and Biocatalysis through Biospectroscopy/TIMB

Editorial: Face Perception across the Life-Span

Face perception is a highly evolved visual skills in humans. This complex ability develops across the life-span, steeply rising in infancy, refining across childhood and adolescence, reaching highest levels in adulthood and declining in old age. As such, the development of face perception comprises multiple skills, including sensory (e.g., mechanisms of holistic, configural and featural perception), cognitive (e.g., memory, processing speed, attentional control), and also emotional and social (e.g., reading and interpreting facial expression) domains. Whereas our understanding of specific functional domains involved in face perception is growing, there is further pressing demand for a multidisciplinary approach toward a more integrated view, describing how face perception ability relates to and develops with other domains of sensory and cognitive functioning. In this research topic we bring together a collection of papers that provide a shot of the current state of the art of theorizing and investigating face perception from the perspective of multiple ability domains. We would like to thank all authors for their valuable contributions that advanced our understanding of face and emotion perception across development

Structural and electronic properties of the active site of [ZnFe] SulE

The function of the recently isolated sulerythrin (SulE) has been investigated using a combination of structural and electronic analyses based on quantum mechanical calculations. In the SulE structure of Fushinobu et al. (2003), isolated from a strictly aerobic archaeon, Sulfolobus tokadaii, a dioxygen-containing species was tentatively included at the active site during crystallographic refinement although the substrate specificity of SulE remains unclear. Studies have suggested that a structurally related enzyme, rubrerythrin, functions as a hydrogen peroxide reductase. Since SulE is a truncated version of rubrerythrin, the enzymes are hypothesized to function similarly. Hence, using available X-ray crystallography data (1.7 Å), we constructed various models of SulE containing a ZnII–Fe active site, differing in the nature of the substrate specificity (O2, H2O2), the oxidation level and the spin state of the iron ion, and the protonation states of the coordinating glutamate residues. Also, the substrate H2O2 is modeled in two possible configurations, differing in the orientation of the hydrogen atoms. Overall, the optimized geometries with an O2 substrate do not show good agreement with the experimentally resolved geometry. In contrast, excellent agreement between crystal structure arrangement and optimized geometries is achieved considering a H2O2 substrate and FeII in both spin states, when Glu92 is protonated. These results suggest that the dioxo species detected at the [ZnFe] active site of sulerythrin is H2O2, rather than an O2 molecule in agreement with experimental data indicating that only the diferrous oxidation state of the dimetal site in rubrerythrin reacts rapidly with H2O2. Based on our computations, we proposed a possible reaction pathway for substrate binding at the ZnFeII site of SulE with a H2O2 substrate. In this reaction pathway, Fe or another electron donor, such as NAD(P)H, catalyzes the reduction of H2O2 to water at the zinc–iron site

Effect of stress factors associated with postharvest citrus conditions on the viability and biocontrol activity of Clavispora lusitaniae strain 146

Only quite recently, we have shown that yeast strains Clavispora lusitaniae 146 and Pichia fermentans 27 can act as efficient biocontrol agents for combating postharvest fungal diseases in lemons. During postharvest and storage conditions, microorganisms are subject to different stress factors that could affect both their survival and their protective capacity. Understanding the tolerance of yeasts to environmental stress factors could support the future development and commercial application of biological control formulations based on such organisms. Thus, the impact of different stressors on the viability and protection efficiency of C. lusitaniae strain 146 and P. fermentans strain 27 was evaluated, and the yeasts were subjected to oxidative stress, thermal treatments, exposure to NaOCl, osmotic stress, and ultraviolet irradiation. Candida oleophila strain O served as the reference control. C. lusitaniae 146 was more resistant to H2O2 in plate assays; however, in liquid media there was no significant difference to the other strains. Strain 146 was less affected by NaOCl, being able to survive with 300 ppm. P. fermentans 27 was the strain most heavily affected by osmotic pressure, while strains 146 and strain O showed a similar adaptation. UV-B irradiation severely affected C. oleophila and P. fermentans, while C. lusitaniae was the most resistant. Strains 146 and 27 were similarly tolerant to thermal shocks, compared to the reference strain, which was less viable. In in vivo tests, exposure to 10 mM H2O2, 45 °C or 200 ppm NaOCl prior to fruit inoculation, reduced the antagonistic activity against the pathogen Penicillium digitatum. However, in no case was the biocontrol efficiency reduced to less than 50%. As C. lusitaniae 146 demonstrated a great potential to combat P. digitatum under a wide range of conditions, the organism is a promising candidate as an effective and valuable alternative to toxic fungicides.Fil: Pereyra, Martina María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Diaz, Mariana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Meinhardt, Friedhelm. Münster Universität; AlemaniaFil: Dib, Julian Rafael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina. Universidad Nacional de Tucumán; Argentin

Complete Genome Sequence of pAP13, a Large Linear Plasmid of a Brevibacterium Strain Isolated from a Saline Lake at 4,200 Meters above Sea Level in Argentina

pAP13 is an 89 kb-linear plasmid hosted by Brevibacterium sp. Ap13, an actinobacterium isolated from the feces of a flamingo from an extremely high-altitude lake in Argentina. Because of the ecological importance of the genus Brevibacterium, the absolute lack of information concerning Brevibacterium linear plasmids, as well as the as the possible ecological significance of this unusual plasmid, pAP13 was completely sequenced, including the inversely oriented termini.Fil: Dib, Julian Rafael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Schuldes, Jörg. Georg August Universität; AlemaniaFil: Thürner, Andrea. Georg August Universität; AlemaniaFil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Daniel, Rolf. Georg August Universität; AlemaniaFil: Meinhardt, Friedhelm. No especifíca

Killer yeasts for the biological control of postharvest fungal crop diseases

Every year and all over the world the fungal decay of fresh fruit and vegetables frequently generates substantial economic losses. Synthetic fungicides, traditionally used to efficiently combat the putrefactive agents, emerged, however, as the cause of environmental and human health issues. Given the need to seek for alternatives, several biological approaches were followed, among which those with killer yeasts stand out. Here, after the elaboration of the complex of problems, we explain the hitherto known yeast killer mechanisms and present the implementation of yeasts displaying such phenotype in biocontrol strategies for pre-or postharvest treatments to be aimed at combating postharvest fungal decay in numerous agricultural products.Fil: Díaz, Mariana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Pereyra, Martina María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Picón Montenegro, Ernesto. Universidad Nacional de Tucumán; ArgentinaFil: Meinhardt, Friedhelm. Universidad Nacional de Tucumán; ArgentinaFil: Dib, Julian Rafael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina. Universidad Nacional de Tucumán; Argentin

First Complete Sequence of a Giant Linear Plasmid from a Micrococcus Strain Isolated from an Extremely High-Altitude Lake

Micrococcus sp. V7, an actinobacterial strain adapted to the extreme conditions of the Laguna Vilama, an extremely high-altitude (4,600mabove sea level) lake in the Argentinian Puna, was found to carry the giant linear plasmid pLMV7. We determined its sequence (92,815 bp) as a prerequisite to the investigation of its role for survival in such a harsh environment.Fil: Dib, Julian Rafael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Schuldes, Jörg. Georg August Universität Göttingen; AndorraFil: Thürner, Andrea. Georg August Universität Göttingen; AndorraFil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Daniel, Rolf. Georg August Universität Göttingen; AndorraFil: Meinhardt, Friedhelm. No especifíca

Screening methods for isolation of biocontrol epiphytic yeasts against penicillium digitatum in lemons

Worldwide, the green rot caused by Penicillium digitatum is one of the most aggressive postharvest diseases of lemons. Searching for sustainable alternatives to chemical fungicides, epi-phytic yeasts as potential biocontrol agents were isolated from citrus fruits using a tailor-made selective medium. For disclosing their antagonistic potential against P. digitatum, obtained isolates were subjected to direct screening methods, both in vitro and in vivo. In the course of the primary in vitro screening that comprised dual culture assays, 43 yeast strains displaying antagonistic activities against the pathogen were selected. Subsequently, such strains were subjected to an in vivo screening that consisted of a microscale test, allowing the selection of six yeast strains for further analysis. In the final screening using macroscale in vivo tests, three strains (AcL2, AgL21, and AgL2) displaying the highest efficiencies to control P. digitatum were identified. The protection efficiencies in lemons were 80 (AcL2), 76.7 (AgL21), and 75% (AgL2). Based on sequence analysis of the PCR amplified D1/D2 domains of the 26S rRNA genes, they were identified as representatives of the species Clavispora lusitaniae. Interestingly, the strains exhibited a broad action spectrum among citrus fruits as they were also able to combat the green mold disease in grapefruit and two orange varieties. The direct screening methods applied in this study favored the recovery of effi-cient candidates for application as biological control agents to combat fungal infestations of citrus fruits.Fil: Pereyra, Martina María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Diaz, Mariana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Soliz Santander, Fabricio Fabián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Poehlein, Anja. Universität Göttingen; AlemaniaFil: Meinhardt, Friedhelm. Westfälische Wilhelms Universität; AlemaniaFil: Daniel, Rolf. Universität Göttingen; AlemaniaFil: Dib, Julian Rafael. Universidad Nacional de Tucumán; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentin

Optical properties of the human round window membrane

Optical techniques are effective tools for diagnostic applications in medicine and are particularly attractive for the noninvasive analysis of biological tissues and fluids in vivo. Noninvasive examinations of substances via a fiber optic probe need to consider the optical properties of biological tissues obstructing the optical path. This applies to the analysis of the human perilymph, which is located behind the round window membrane. The composition of this inner ear liquid is directly correlated to inner ear hearing loss. In this work, experimental methods for studying the optical properties of the human round window membrane ex vivo are presented. For the first time, a comprehensive investigation of this tissue is performed, including optical transmission, forward scattering, and Raman scattering. The results obtained suggest the application of visible wavelengths (>400nm) for investigating the perilymph behind the round window membrane in future. © 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)