Visualizing the molecular recognition trajectory of an intrinsically disordered protein using multinuclear relaxation dispersion NMR

Despite playing important roles throughout biology, molecular recognition mechanisms in intrinsically disordered proteins remain poorly understood. We present a combination of (1)H(N), (13)C', and (15)N relaxation dispersion NMR, measured at multiple titration points, to map the interaction between the disordered domain of Sendai virus nucleoprotein (NT) and the C-terminal domain of the phosphoprotein (PX). Interaction with PX funnels the free-state equilibrium of NT by stabilizing one of the previously identified helical substates present in the prerecognition ensemble in a nonspecific and dynamic encounter complex on the surface of PX. This helix then locates into the binding site at a rate coincident with intrinsic breathing motions of the helical groove on the surface of PX. The binding kinetics of complex formation are thus regulated by the intrinsic free-state conformational dynamics of both proteins. This approach, providing high-resolution structural and kinetic information about a complex folding and binding interaction trajectory, can be applied to a number of experimental systems to provide a general framework for understanding conformational disorder in biomolecular function

Stres i radna sposobnost radnika u naftnoj industriji

This cross-sectional study conducted between March and June 2006 examined stress at work and work ability of 180 people with different workplaces within an oil company. Office, laboratory, and oil-field workers were invited to complete the “Occupational Stress Assessment Questionnaire – the Oil Industry Version and Work Ability Index (WAI) Questionnaire”. The overall response rate was 69.4 %, and the final sample size was 125 workers who completed the questionnaires (57 office, 41 laboratory, 27 oil-field workers). Office, laboratory, and oil-field workers differed significantly with respect to age (P<0.001). The oldest were oil-field workers and the youngest were office workers. The average WAI score for office workers was 44.9, for laboratory workers 43.2 and for field workers 39.7, indicating satisfying work ability. After adjusting for age, the difference in WAI score between the groups of workers was still significant (P<0.001). Over 75 % of all workers believed their job was stressful, but the perception of specific stressors depended on the workplace.Cilj ovog ispitivanja bio je procijeniti doživljaj stresa na radnome mjestu i radnu sposobnost zaposlenih u različitim dijelovima radnog procesa naftne industrije. Presječno istraživanje provedeno je u hrvatskoj naftnoj industriji, u razdoblju od ožujka do lipnja 2006. s uzorkom od 180 prigodno odabranih zaposlenika. Zaposlenici u uredu, laboratoriju za preradu nafte i naftnom pogonu trebali su ispuniti Upitnik o stresu na radu – verzija za naftnu industriju i Upitnik za procjenu indeksa radne sposobnosti (WAI). Ukupni odaziv ispitanika bio je 69,4 % te je obrađeno 125 ispunjenih upitnika (57 radnika iz ureda, 41 iz laboratorija i 27 iz naftnog pogona). Radnici iz ureda, laboratorija i naftnih pogona značajno su se razlikovali u dobi (P<0,001). Najstariji su bili radnici u naftnim pogonima, dok su najmlađi bili radnici u uredu. Prosječni WAI za uredske zaposlenike bio je 44,9, za laboratorijske 43,2, a za zaposlenike u naftnom pogonu 39,7, što upućuje na zadovoljavajuću radnu sposobnost. Uzevši u obzir utjecaj dobi pri testiranju razlika, utvrđeno je kako se WAI promatranih skupina statistički značajno razlikuju (P<0,001). Više od tri četvrtine svih ispitanika procjenjuje svoj posao kao stresan, no vrste stresora koje doživljavaju razlikuju se ovisno o radnome mjestu

Obesity prevalence from a European perspective: a systematic review

<p>Abstract</p> <p>Background</p> <p>Obesity has been recognised as an important contributing factor in the development of various diseases, but comparative data on this condition are limited. We therefore aimed to identify and discuss current epidemiological data on the prevalence of obesity in European countries.</p> <p>Methods</p> <p>We identified relevant published studies by means of a MEDLINE search (1990–2008) supplemented by information obtained from regulatory agencies. We only included surveys that used direct measures of weight and height and were representative of each country's overall population.</p> <p>Results</p> <p>In Europe, the prevalence of obesity (body mass index ≥ 30 kg/m²) in men ranged from 4.0% to 28.3% and in women from 6.2% to 36.5%. We observed considerable geographic variation, with prevalence rates in Central, Eastern, and Southern Europe being higher than those in Western and Northern Europe.</p> <p>Conclusion</p> <p>In Europe, obesity has reached epidemic proportions. The data presented in our review emphasise the need for effective therapeutic and preventive strategies.</p

Small-angle X-ray scattering- and nuclear magnetic resonance-derived conformational ensemble of the highly flexible antitoxin PaaA2.

International audienceAntitoxins from prokaryotic type II toxin-antitoxin modules are characterized by a high degree of intrinsic disorder. The description of such highly flexible proteins is challenging because they cannot be represented by a single structure. Here, we present a combination of SAXS and NMR data to describe the conformational ensemble of the PaaA2 antitoxin from the human pathogen E. coli O157. The method encompasses the use of SAXS data to filter ensembles out of a pool of conformers generated by a custom NMR structure calculation protocol and the subsequent refinement by a block jackknife procedure. The final ensemble obtained through the method is validated by an established residual dipolar coupling analysis. We show that the conformational ensemble of PaaA2 is highly compact and that the protein exists in solution as two preformed helices, connected by a flexible linker, that probably act as molecular recognition elements for toxin inhibition

Targeting the disordered C terminus of PTP1B with an allosteric inhibitor

PTP1B, a validated therapeutic target for diabetes and obesity, has a critical positive role in HER2 signaling in breast tumorigenesis. Efforts to develop therapeutic inhibitors of PTP1B have been frustrated by the chemical properties of the active site. We define a new mechanism of allosteric inhibition that targets the C-terminal, noncatalytic segment of PTP1B. We present what is to our knowledge the first ensemble structure of PTP1B containing this intrinsically disordered segment, within which we identified a binding site for the small-molecule inhibitor MSI-1436. We demonstrate binding to a second site close to the catalytic domain, with cooperative effects between the two sites locking PTP1B in an inactive state. MSI-1436 antagonized HER2 signaling, inhibited tumorigenesis in xenografts and abrogated metastasis in the NDL2 mouse model of breast cancer, validating inhibition of PTP1B as a therapeutic strategy in breast cancer. This new approach to inhibition of PTP1B emphasizes the potential of disordered segments of proteins as specific binding sites for therapeutic small molecules

Characterizing Protein-Protein Interactions Using Solution NMR Spectroscopy

In this chapter, we describe how NMR chemical shift titrations can be used to study the interaction between two proteins with emphasis on mapping the interface of the complex and determining the bind- ing affinity from a quantitative analysis of the experimental data. In particular, we discuss the appearance of NMR spectra in different chemical exchange regimes (fast, intermediate, and slow) and how these regimes affect NMR data analysis