SECIS elements in the coding regions of selenoprotein transcripts are functional in higher eukaryotes

Expression of selenocysteine (Sec)-containing proteins requires the presence of a cis-acting mRNA structure, called selenocysteine insertion sequence (SECIS) element. In bacteria, this structure is located in the coding region immediately downstream of the Sec-encoding UGA codon, whereas in eukaryotes a completely different SECIS element has evolved in the 3′-untranslated region. Here, we report that SECIS elements in the coding regions of selenoprotein mRNAs support Sec insertion in higher eukaryotes. Comprehensive computational analysis of all available viral genomes revealed a SECIS element within the ORF of a naturally occurring selenoprotein homolog of glutathione peroxidase 4 in fowlpox virus. The fowlpox SECIS element supported Sec insertion when expressed in mammalian cells as part of the coding region of viral or mammalian selenoproteins. In addition, readthrough at UGA was observed when the viral SECIS element was located upstream of the Sec codon. We also demonstrate successful de novo design of a functional SECIS element in the coding region of a mammalian selenoprotein. Our data provide evidence that the location of the SECIS element in the untranslated region is not a functional necessity but rather is an evolutionary adaptation to enable a more efficient synthesis of selenoproteins

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

Diversity of Protein and mRNA Forms of Mammalian Methionine Sulfoxide Reductase B1 Due to Intronization and Protein Processing

Background: Methionine sulfoxide reductases (Msrs) are repair enzymes that protect proteins from oxidative stress by catalyzing stereospecific reduction of oxidized methionine residues. MsrB1 is a selenocysteine-containing cytosolic/nuclear Msr with high expression in liver and kidney. Principal Findings: Here, we identified differences in MsrB1 gene structure among mammals. Human MsrB1 gene consists of four, whereas the corresponding mouse gene of five exons, due to occurrence of an additional intron that flanks the stop signal and covers a large part of the 3′-UTR. This intron evolved in a subset of rodents through intronization of exonic sequences, whereas the human gene structure represents the ancestral form. In mice, both splice forms were detected in liver, kidney, brain and heart with the five-exon form being the major form. We found that both mRNA forms were translated and supported efficient selenocysteine insertion into MsrB1. In addition, MsrB1 occurs in two protein forms that migrate as 14 and 5 kDa proteins. We found that each mRNA splice form generated both protein forms. The abundance of the 5 kDa form was not influenced by protease inhibitors, replacement of selenocysteine in the active site or mutation of amino acids in the cleavage site. However, mutation of cysteines that coordinate a structural zinc decreased the levels of 5 and 14 kDa forms, suggesting importance of protein structure for biosynthesis and/stability of these forms. Conclusions: This study characterized unexpected diversity of protein and mRNA forms of mammalian selenoprotein MsrB1

Different Catalytic Mechanisms in Mammalian Selenocysteine- and Cysteine-Containing Methionine-R-Sulfoxide Reductases

Selenocysteine (Sec) is found in active sites of several oxidoreductases in which this residue is essential for catalytic activity. However, many selenoproteins have fully functional orthologs, wherein cysteine (Cys) occupies the position of Sec. The reason why some enzymes evolve into selenoproteins if the Cys versions may be sufficient is not understood. Among three mammalian methionine-R-sulfoxide reductases (MsrBs), MsrB1 is a Sec-containing protein, whereas MsrB2 and MsrB3 contain Cys in the active site, making these enzymes an excellent system for addressing the question of why Sec is used in biological systems. In this study, we found that residues, which are uniquely conserved in Cys-containing MsrBs and which are critical for enzyme activity in MsrB2 and MsrB3, were not required for MsrB1, but increased the activity of its Cys mutant. Conversely, selenoprotein MsrB1 had a unique resolving Cys reversibly engaged in the selenenylsulfide bond. However, this Cys was not necessary for activities of either MsrB2, MsrB3, or the Cys mutant of MsrB1. We prepared Sec-containing forms of MsrB2 and MsrB3 and found that they were more than 100-fold more active than the natural Cys forms. However, these selenoproteins could not be reduced by the physiological electron donor, thioredoxin. Yet, insertion of the resolving Cys, which was conserved in MsrB1, into the selenoprotein form of MsrB3 restored the thioredoxin-dependent activity of this enzyme. These data revealed differences in catalytic mechanisms between selenoprotein MsrB1 and non-selenoproteins MsrB2 and MsrB3, and identified catalytic advantages and disadvantages of Sec- and Cys-containing proteins. The data also suggested that Sec- and Cys-containing oxidoreductases require distinct sets of active-site features that maximize their catalytic efficiencies and provide strategies for protein design with improved catalytic properties

Office of Research and Graduate Studies -- Annual Report 2003-2004

Contents Science and Engineering page Recombinant Bandage 02 Advanced Computing, Everyday Life 04 Software Engineering 05 Silicon Nanotubes. 06 Nutritional Genomics and Nanomaterials. 08 Genetics of Virulence 09 Rapid PCR Device. 10 Selenium, Cancer and Aging 12 Education Math in the Middle Institute. 14 Project Fulcrum 16 School Readiness for Parents 17 Behavioral Science Assessing Threatening Behavior 18 Family Dynamics of Infertility 19 Arts & Humanities Encyclopedia of the Great Plains 20 Global Politics 22 Sculpture Conservation. 22 Commission with Philip Glass 23 Rising Stars page Luminescence. 24 Giant Thunderstorms 24 Debugging Software 25 Technology Development Robotic Traffic Barrels 26 Buffalograss for Turf 26 Textiles from Cornhusks 27 Graduate Studies Undergraduate Research 28 Professional Development 29 Interactive Economics Education 29 Extending Our Reach The Nebraska Lectures 30 Research Fair 2004 30 Water Law, Science and Policy 31 Financials: FY 2003-2004 3

From prediction to function: Polyamine biosynthesis and formate metabolism in the α- and ε-Proteobacteria

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Office of Research and Graduate Studies -- Annual Report 2002/2003

Contents 01 Introduction 03 Nanomagnetics & Mesospin Structures 05 Redox Biology 07 Virology & Infectious Diseases 09 Bioprocessing & Vaccine Development 11 Plant Genomics 13 Complex Environmental Systems 15 Behavioral Sciences 17 Education in the 21st Century 19 Digital Texts & Contemporary Writing 21 Nanomanufacturing & Advanced Materials 23 Initiatives 25 Future 27 Graduate Studies 29 Technology Development 31 University of Nebraska Press 32 Financials 33 Inspiring Excellenc

Selenium and selenoproteins in viral infection with potential relevance to COVID-19

Selenium is a trace element essential to human health largely because of its incorporation into selenoproteins that have a wide range of protective functions. Selenium has an ongoing history of reducing the incidence and severity of various viral infections; for example, a German study found selenium status to be significantly higher in serum samples from surviving than non-surviving COVID-19 patients. Furthermore, a significant, positive, linear association was found between the cure rate of Chinese patients with COVID-19 and regional selenium status. Moreover, the cure rate continued to rise beyond the selenium intake required to optimise selenoproteins, suggesting that selenoproteins are probably not the whole story. Nonetheless, the significantly reduced expression of a number of selenoproteins, including those involved in controlling ER stress, along with increased expression of IL-6 in SARS-CoV-2 infected cells in culture suggests a potential link between reduced selenoprotein expression and COVID-19-associated inflammation. In this comprehensive review, we describe the history of selenium in viral infections and then go on to assess the potential benefits of adequate and even supra-nutritional selenium status. We discuss the indispensable function of the selenoproteins in coordinating a successful immune response and follow by reviewing cytokine excess, a key mediator of morbidity and mortality in COVID-19, and its relationship to selenium status. We comment on the fact that the synthetic redox-active selenium compound, ebselen, has been found experimentally to be a strong inhibitor of the main SARS-CoV-2 protease that enables viral maturation within the host. That finding suggests that redox-active selenium species formed at high selenium intake might hypothetically inhibit SARS-CoV-2 proteases. We consider the tactics that SARS-CoV-2 could employ to evade an adequate host response by interfering with the human selenoprotein system. Recognition of the myriad mechanisms by which selenium might potentially benefit COVID-19 patients provides a rationale for randomised, controlled trials of selenium supplementation in SARS-CoV-2 infection

Discovery and Molecular Characterization of Selenoprotein M in the Salivary Glands of \u3ci\u3eAmblyomma maculatum\u3c/i\u3e, the Gulf Coast Tick

The Gulfcoast ticks transmit disease-causing pathogens to humans and animals. Rickettsia parkeri is notable among the pathogens transmitted by A. maculatum to humans. Heavy infestations of A. maculatum on animal ears cause them to become thickened and curled, a condition commonly called gotch ear. The tick\u27s multifunctional salivary glands are vital to their biological success and likely also play a critical role in transmission of disease; tick saliva contains a broad array of secretory products that facilitate prolonged tick attachment and feeding; disrupting tick blood feeding or inactivating key tick salivary proteins presents a novel strategy for tick-borne disease prevention. Sequencing of A. maculatum salivary gland normalized eDNA library revealed a gene sequence homologous to SelenoproteinM. Trace element Selenium exhibits a variety of functions in the form of Selenoproteins, most importantly, as an antioxidant enzyme. SelenoproteinM is expressed in A. maculatum salivary glands in almost all the feeding phases. RNA interference (RNAi) was used to assess the role of this molecule for tick feeding success. Silencing of was demonstrated by reduced transcript in salivary glands removed from partially fed ticks. Disrupting expression of SelenoproteinM by RNAi induced rapid weight gain in engorging female ticks in early phase of feeding. Since many Selenoproteins are involved in antioxidant activities, we further evaluated the antioxidant capacity of tick tissues treated with SeiM-dsRNA. There was a significant reduction in the antioxidant capacity in SelenoproteinM silenced tick tissues

Identification of Host Cellular Protein Substrates of SARS-COV-2 Main Protease

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