Dancing Through Life: Allosteric Transitions and Structural Analysis of Hsp70 and Hsp110 Chaperone Proteins

The molecular chaperone protein Hsp70 is centrally involved in cellular homeostasis by assisting in the folding and degradation of protein substrates. Hsp70 is joined by co-chaperones, such as Hsp110, which contribute to specialized tasks of the Hsp70 complex. Imbalances of this heat shock protein system are believed to be involved with the deregulation of cancer pathways and other human diseases. Better understanding of how these heat shock proteins work at the molecular level, which has been investigated using molecular docking tools, will give more clues about biological function. Simulating the formation and function of Hsp70 based chaperone complexes could provide new information about the control and regulation of these processes and well as new areas of exploration for drug discovery

Dissecting Structure-Encoded Determinants of Allosteric Cross-Talk between Post-Translational Modification Sites in the Hsp90 Chaperones

Post-translational modifications (PTMs) represent an important regulatory instrument that modulates structure, dynamics and function of proteins. The large number of PTM sites in the Hsp90 proteins that are scattered throughout different domains indicated that synchronization of multiple PTMs through a combinatorial code can be invoked as an important mechanism to orchestrate diverse chaperone functions and recognize multiple client proteins. In this study, we have combined structural and coevolutionary analysis with molecular simulations and perturbation response scanning analysis of the Hsp90 structures to characterize functional role of PTM sites in allosteric regulation. The results reveal a small group of conserved PTMs that act as global mediators of collective dynamics and allosteric communications in the Hsp90 structures, while the majority of flexible PTM sites serve as sensors and carriers of the allosteric structural changes. This study provides a comprehensive structural, dynamic and network analysis of PTM sites across Hsp90 proteins, identifying specific role of regulatory PTM hotspots in the allosteric mechanism of the Hsp90 cycle. We argue that plasticity of a combinatorial PTM code in the Hsp90 may be enacted through allosteric coupling between effector and sensor PTM residues, which would allow for timely response to structural requirements of multiple modified enzymes

A Review of Rare Pion and Muon Decays

After a decade of no measurements of pion and muon rare decays, PIBETA, a new experimental program is producing its first results. We report on a new experimental study of the pion beta decay, Pi(+) -> Pi(0) e(+) Nu, the Pi(e2 gamma) radiative decay, Pi(+) -> e(+) Nu Gamma, and muon radiative decay, Mu -> e Nu Gamma. The new results represent four- to six-fold improvements in precision over the previous measurements. Excellent agreement with Standard Model predictions is observed in all channels except for one kinematic region of the Pi(e2 gamma) radiative decay involving energetic photons and lower-energy positrons.Comment: 10 pages, 6 figures, 2 tables, invited talk presented at MESON 2004, 8th Int'l. Workshop on Meson Production, Properties and Interaction, Krakow, Poland 4-8 June 200

Characteristics of Non-Fatal Attacks by Black Bears: Conterminous United States, 2000–2017

Attacks on humans by bears (Ursus spp.) have increased in recent decades, as both human and bear populations have increased. To help mitigate the risk of future attacks, it is important to understand the circumstances in past attacks. Information and analyses exist regarding fatal attacks by both American black bears (Ursus americanus) and brown bears (U. arctos) as well as non-fatal attacks by brown bears. No similarly thorough analyses on non-fatal attacks by black bears are available. Our study addressed this information gap by analyzing all (n = 210) agency-confirmed, non-fatal attacks by black bears in the 48 conterminous United States during 2000 to 2017. Most attacks were defensive (52%), while 15% were predatory and 33% were food-motivated. Of defensive attacks, 85% were by female bears, and 91% of those females had young. Of predatory attacks, 95% were by male bears, and of food-motivated attacks, 80% were by male bears. Forty percent of defensive attacks by female bears involved dogs (Canis lupus familiaris). Sixty-four percent had an attractant present during the attack and 74% indicated there were reports of property damage by bears or of bears getting a food-reward in the area prior to the attack. A classification and regression tree model show the highest proportion of severe attacks were among a female victim who was with a dog and who fought back during an attack. When compared with previous studies of fatal attacks by black bears, which are typically predatory attacks by male bears, our results illustrate clear differences between fatal and non-fatal attacks. Our study also lends evidence to the hypothesis that dogs can trigger defensive attacks by black bears. These results have implications for risk assessment, attack mitigation, and how we advise the public to respond to an attacking bear

Stipulations in Performance Contracting M&V: the Good, the Bad, and the Ugly

Performance contractors (PC) often use stipulations for part or all of their measurement & verification (M&V) efforts. The value of stipulations are low cost and easy implementation (good). Disadvantages include uncertain savings estimates (bad) and potential for disputes and lawsuits (ugly). PCs and customers sometimes misuse or abuse stipulations either by stipulating the savings directly or stipulating parameters based on limited or unreliable information. The purpose of M&V is to provide assurance that project savings exist. Improper and excessive reliance on stipulations may effectively nullify savings guarantees and also miss opportunities to assure measure performance by using verification data for feedback. A review of PCs in the federal sector shows significant reliance on stipulations; private-sector PCs are presumed similar. Recognized M&V guidelines such as ASHRAE 14-P, IPMVP, and FEMP discuss the use of stipulations. Recent changes to the IPMVP and FEMP guidelines resulted in diverging attitudes towards stipulations with the IPMVP now requiring some measurements. In response, FEMP is developing guidelines for using stipulations in federal-sector performance contracts that can be applied to privatesector PCs as well. Proper use of stipulations requires balancing costs with savings uncertainty

Pion double charge exchange on 4He

The doubly differential cross sections for the $^4$He$(\pi^+,\pi^-) 4p$ reaction were calculated using both a two-nucleon sequential single charge exchange model and an intranuclear cascade code. Final state interactions between the two final protons which were the initial neutrons were included in both methods. At incident pion energies of 240 and 270 MeV the low-energy peak observed experimentally in the energy spectrum of the final pions can be understood only if the contribution of pion production is included. The calculated cross sections are compared with data.Comment: 25 pages, 9 figure

Estimating Grizzly and Black Bear Population Abundance and Trend in Banff National Park Using Noninvasive Genetic Sampling

We evaluated the potential of two noninvasive genetic sampling methods, hair traps and bear rub surveys, to estimate population abundance and trend of grizzly (Ursus arctos) and black bear (U. americanus) populations in Banff National Park, Alberta, Canada. Using Huggins closed population mark-recapture models, we obtained the first precise abundance estimates for grizzly bears ( = 73.5, 95% CI = 64–94 in 2006;  = 50.4, 95% CI = 49–59 in 2008) and black bears ( = 62.6, 95% CI = 51–89 in 2006;  = 81.8, 95% CI = 72–102 in 2008) in the Bow Valley. Hair traps had high detection rates for female grizzlies, and male and female black bears, but extremely low detection rates for male grizzlies. Conversely, bear rubs had high detection rates for male and female grizzlies, but low rates for black bears. We estimated realized population growth rates, lambda, for grizzly bear males ( = 0.93, 95% CI = 0.74–1.17) and females ( = 0.90, 95% CI = 0.67–1.20) using Pradel open population models with three years of bear rub data. Lambda estimates are supported by abundance estimates from combined hair trap/bear rub closed population models and are consistent with a system that is likely driven by high levels of human-caused mortality. Our results suggest that bear rub surveys would provide an efficient and powerful means to inventory and monitor grizzly bear populations in the Central Canadian Rocky Mountains

Exploring working conditions as determinants of job satisfaction: an empirical test among Catalonia service workers

Job satisfaction is particularly important in the service industry since it involves direct contact with customers and thus has a direct influence on company performance. We analyzed the impact of ten working conditions on job satisfaction by means of structural equation modelling in a representative stratified random sample of 1553 service sector employees in Catalonia (Spain). We found significant effects in social aspects (recognition of a job well done and social support), followed by psychological loads (emotional demands and job insecurity) and by task contents (development & meaning and predictability). These variables explained 50% of the variance in job satisfaction

Evaluation of a new arterial pressure-based cardiac output device requiring no external calibration

<p>Abstract</p> <p>Background</p> <p>Several techniques have been discussed as alternatives to the intermittent bolus thermodilution cardiac output (CO_PAC) measurement by the pulmonary artery catheter (PAC). However, these techniques usually require a central venous line, an additional catheter, or a special calibration procedure. A new arterial pressure-based cardiac output (CO_AP) device (FloTrac™, Vigileo™; Edwards Lifesciences, Irvine, CA, USA) only requires access to the radial or femoral artery using a standard arterial catheter and does not need an external calibration. We validated this technique in critically ill patients in the intensive care unit (ICU) using CO_PACas the method of reference.</p> <p>Methods</p> <p>We studied 20 critically ill patients, aged 16 to 74 years (mean, 55.5 ± 18.8 years), who required both arterial and pulmonary artery pressure monitoring. CO_PACmeasurements were performed at least every 4 hours and calculated as the average of 3 measurements, while CO_APvalues were taken immediately at the end of bolus determinations. Accuracy of measurements was assessed by calculating the bias and limits of agreement using the method described by Bland and Altman.</p> <p>Results</p> <p>A total of 164 coupled measurements were obtained. Absolute values of CO_PACranged from 2.80 to 10.80 l/min (mean 5.93 ± 1.55 l/min). The bias and limits of agreement between CO_PACand CO_APfor unequal numbers of replicates was 0.02 ± 2.92 l/min. The percentage error between CO_PACand CO_APwas 49.3%. The bias between percentage changes in CO_PAC(ΔCO_PAC) and percentage changes in CO_AP(ΔCO_AP) for consecutive measurements was -0.70% ± 32.28%. CO_PACand CO_APshowed a Pearson correlation coefficient of 0.58 (<it>p </it>< 0.01), while the correlation coefficient between ΔCO_PACand ΔCO_APwas 0.46 (<it>p </it>< 0.01).</p> <p>Conclusion</p> <p>Although the CO_APalgorithm shows a minimal bias with CO_PACover a wide range of values in an inhomogeneous group of critically ill patients, the scattering of the data remains relative wide. Therefore, the used algorithm (V 1.03) failed to demonstrate an acceptable accuracy in comparison to the clinical standard of cardiac output determination.</p

Hsp90 middle domain phosphorylation initiates a complex conformational program to recruit the ATPase-stimulating cochaperone Aha1

Complex conformational dynamics are essential for function of the dimeric molecular cha- perone heat shock protein 90 (Hsp90), including transient, ATP-biased N-domain dimer- ization that is necessary to attain ATPase competence. The intrinsic, but weak, ATP hydrolyzing activity of human Hsp90 is markedly enhanced by the co-chaperone Aha1. However, the cellular concentration of Aha1 is substoichiometric relative to Hsp90. Here we report that initial recruitment of this cochaperone to Hsp90 is markedly enhanced by phosphorylation of a highly conserved tyrosine (Y313 in Hsp90α) in the Hsp90 middle domain. Importantly, phosphomimetic mutation of Y313 promotes formation of a transient complex in which both N- and C-domains of Aha1 bind to distinct surfaces of the middle domains of opposing Hsp90 protomers prior to ATP-directed N-domain dimerization. Thus, Y313 represents a phosphorylation-sensitive conformational switch, engaged early after client loading, that affects both local and long-range conformational dynamics to facilitate initial recruitment of Aha1 to Hsp90