Weak Intra-Ring Allosteric Communications of the Archaeal Chaperonin Thermosome Revealed by Normal Mode Analysis

Chaperonins are molecular machines that use ATP-driven cycles to assist misfolded substrate proteins to reach the native state. During the functional cycle, these machines adopt distinct nucleotide-dependent conformational states, which reflect large-scale allosteric changes in individual subunits. Distinct allosteric kinetics has been described for the two chaperonin classes. Bacterial (group I) chaperonins, such as GroEL, undergo concerted subunit motions within each ring, whereas archaeal and eukaryotic chaperonins (group II) undergo sequential subunit motions. We study these distinct mechanisms through a comparative normal mode analysis of monomer and double-ring structures of the archaeal chaperonin thermosome and GroEL. We find that thermosome monomers of each type exhibit common low-frequency behavior of normal modes. The observed distinct higher-frequency modes are attributed to functional specialization of these subunit types. The thermosome double-ring structure has larger contribution from higher-frequency modes, as it is found in the GroEL case. We find that long-range intersubunit correlation of amino-acid pairs is weaker in the thermosome ring than in GroEL. Overall, our results indicate that distinct allosteric behavior of the two chaperonin classes originates from different wiring of individual subunits as well as of the intersubunit communications.     

A pilot study to stabilize normoglycemia during an educational camp for children and adolescents with type 1 diabetes mellitus

Background: Children and adolescents with type 1 diabetes mellitus (DM) who participate in diabetes camps do not often achieve stable, normoglycemic control, largely because changes in the campers' activity levels and food options necessitate adjustments to their insulin use and nutritional therapies. It would seem logical, with the abundance of diabetes education and professional consultation freely available at these camps, that the glycemic levels of these young campers could approach normal values.Objective: This informal study was designed to explore the feasibility of safely achieving stable, short-term normo-glycemic control in children and adolescents with recent-onset type 1 DM attending a diabetes camp.Methods: A multidisciplinary team worked with children and adolescents 6 to 18 years of age during a residential 3-day/2-night diabetes camp. Demographic data were compiled from the application forms completed by the campers and signed by the campers and their parents. The staff functioned in 2 distinct roles: as managers (securing time, task, technique, and territory boundaries) and as consultants (addressing participants' educational, social, and emotional needs). The staff supported the campers in their attempts to quickly and safely achieve tight normoglycemic control (ie, 71–99 mg/dL) and stability (ie, an estimated mean amplitude of glycemic excursion [eMAGE] score ≤95) through their firsthand experience with self-directed learning methods, basal-bolus insulin analogue therapy, and a diet low in concentrated carbohydrates (CHOs). Campers chose foods from meal buffets, calculated preprandial and complementary doses of ultra-rapid insulin, and participated in physical exercise and self-monitoring of blood glucose (SMBG) at will. SMBG values retained in each camper's combined glucose/ketone monitor furnished statistical data. Initial and final glycosylated hemoglobin values were not measured because 3 days of glycemic control—at any BG level—would not be expected and have not been reported to produce significant changes. No follow-up of the campers was planned or possible.Results: Six boys and 3 girls (aged 8–17 years; mean [SD] age, 11.8 [2.6] years; mean duration of diabetes, 1.62 [0.88] years) agreed to participate in the study. All but 1 of the campers were preadolescents. Mean BG levels on arrival and departure were 209 (101.5) and 81 (12.8) mg/dL, respectively (P < 0.003). The mean 3-day BG level was 95 (21.2) mg/dL. The 3-day mean eMAGE score (66.5 [28.1]) indicated stable glycemic control. Seven of the 9 campers (78%) returned to the camp the following year (2007).Conclusions: Combining self-directed educational methods for learning diabetes self-management with insulin analogues in a basal-bolus therapy regimen, ad libitum physical activity and SMBG, and a diet low in concentrated CHOs, campers rapidly established routinely normal daily mean BG levels and glycemic stability.     

Adaptations and responses of Dasymutilla occidentalis (Hymenoptera: Mutillidae) to predators

The mutillid wasp Dasymutilla occidentalis possesses several adaptations and exhibits a number of responses wich appear to be of defensive value: a long mobile sting with powerful venom; a strong, rounded and slippery cuticle; an ability to run very rapidly and evasively; an aposematic warning coloration pattern; and the ability to respond to an attack by making stridulatory sounds and by releasing a chemical secretion or both. The effectiveness of these defenses is supported by tests utilizing various vertebrate and arthropod predators. The raison d'être of the multiple lines of defense possessed by D. occidentalis and the relative value of each line of defense are discussed. It is postulated that aposematic coloration, audible stridulation, and a volatile defensive exudate all function primarily as part of an early warning system enabling a predator to recognize this wasp-with its very algogenic venom-as unpalatable and potentially dangerous.

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Zusammenfassung Die Mutillide Wespe Dasymutilla occidentalis besitzt verschiedene Anpassungen und zeigt eine Anzahl von Reaktionen, die für die Verteidigung von Wert sind: ein langer, beweglicher Stachel mit starkem Gift, eine starke, runde und glatte Kutikula, die Möglichkeit, sehr schnell und ausweichend zu laufen sowie ein aposematisches Warn-Farben-Muster. Desweiteren ist sie fähig, einem Angriff mit einem knisternden Ton entgegenzutreten sowie ein chemisches Sekret abzugeben oder auch beides. Im Labor durchgeführte Zusammenstöße zwischen vertebraten und invertebraten Räubern und D. occidentalis beweisen klar den Wert der ganzen Anzahl von Verteidigungsmechanismen für die Wespe.Diese Zusammenstöße liefern auch einen Einblick in die raison d'être der vielseitigen Verteidigung. die stärkere Kutikula und ihre Glätte, Haupteigenschaften zum überleben gegen Räuber, funktionieren gleichzeitig mit dem Stich zum Schutz gegen Vertebraten und mit schneller Fluchtmöglichkeit zum Schutz gegen die meisten Invertebraten. Das akustische Geräusch scheint eine Hilfsverteidigung zu sein wenigstens gegen einige Spinnen und vermutlich auch gegen einige Vertebraten. Die chemische Sekretion, die hauptsächlich aus 4-methyl-3-heptanon besteht, scheint möglicherweise direkten Verteidigungswert gegen einige Eidechsen zu haben und funktioniert höchstwahrscheinlich hauptsächlich im Zusammenhang mit der roten und schwarzen aposematischen Färbung und dem knisternden Ton als vielseitiges Warnsystem, das fähig ist, durch Signalisieren allen potentiellen vertebraten Räubern mitzuteilen, daß dieses Insekt ungenießbar ist.

     

Attenuation of SARS‐CoV‐2 replication and associated inflammation by concomitant targeting of viral and host cap 2'‐O‐ribose methyltransferases

The SARS‐CoV‐2 infection cycle is a multistage process that relies on functional interactions between the host and the pathogen. Here, we repurposed antiviral drugs against both viral and host enzymes to pharmaceutically block methylation of the viral RNA 2''‐O‐ribose cap needed for viral immune escape. We find that the host cap 2''‐O‐ribose methyltransferase MTr1 can compensate for loss of viral NSP16 methyltransferase in facilitating virus replication. Concomitant inhibition of MTr1 and NSP16 efficiently suppresses SARS‐CoV‐2 replication. Using in silico target‐based drug screening, we identify a bispecific MTr1/NSP16 inhibitor with anti‐SARS‐CoV‐2 activity in vitro and in vivo but with unfavorable side effects. We further show antiviral activity of inhibitors that target independent stages of the host SAM cycle providing the methyltransferase co‐substrate. In particular, the adenosylhomocysteinase (AHCY) inhibitor DZNep is antiviral in in vitro, in ex vivo, and in a mouse infection model and synergizes with existing COVID‐19 treatments. Moreover, DZNep exhibits a strong immunomodulatory effect curbing infection‐induced hyperinflammation and reduces lung fibrosis markers ex vivo. Thus, multispecific and metabolic MTase inhibitors constitute yet unexplored treatment options against COVID‐19.     

Insulin and glucose in neonatal calves after peroral insulin and intravenous glucose administration.

Effects of peroral insulin on plasma concentrations of immunoreactive insulin (IRI) and glucose in newborn calves were studied. Bovine insulin was administered in amounts of 0.5 mg/kg body weight immediately preceding first colostrum. Thereafter, neither an increased IRI response nor a lowering of blood glucose level were observed, indicating that insulin was either not absorbed from the intestine or possibly retained in the liver. Feeding of whole milk was followed by a higher rise in IRI and glucose concentrations than feeding of colostrum after po insulin. However, when compared with 1-3-month old calves, IRI responses to feeding and to iv infused glucose were markedly smaller on the first and second day of life respectively, while glucose responses were similar. This indicates that insulin secretory mechanisms are not fully developed in the newborn calf.     

Inhibition of melanoma development in the Nras(Q61K)::Ink4a−/− mouse model by the small molecule BI‐69A11

To date, there are no effective therapies for tumors bearing NRAS mutations, which are present in 15–20% of human melanomas. Here we extend our earlier studies where we demonstrated that the small molecule BI‐69A11 inhibits the growth of melanoma cell lines. Gene expression analysis revealed the induction of interferon‐ and cell death‐related genes that were associated with responsiveness of melanoma cell lines to BI‐69A11. Strikingly, the administration of BI‐69A11 inhibited melanoma development in genetically modified mice bearing an inducible form of activated Nras and a deletion of the Ink4a gene (Nras^(Q61K)::Ink4a^?/?). Biweekly administration of BI‐69A11 starting at 10 weeks or as late as 24 weeks after the induction of mutant Nras expression inhibited melanoma development (100 and 36%, respectively). BI‐69A11 treatment did not inhibit the development of histiocytic sarcomas, which constitute about 50% of the tumors in this model. BI‐69A11‐resistant Nras^(Q61K)::Ink4a^?/? tumors exhibited increased CD45 expression, reflective of immune cell infiltration and upregulation of gene networks associated with the cytoskeleton, DNA damage response, and small molecule transport. The ability to attenuate the development of NRAS mutant melanomas supports further development of BI‐69A11 for clinical assessment.