Insights into Coupled Folding and Binding Mechanisms from Kinetic Studies.

Intrinsically disordered proteins (IDPs) are characterized by a lack of persistent structure. Since their identification more than a decade ago, many questions regarding their functional relevance and interaction mechanisms remain unanswered. Although most experiments have taken equilibrium and structural perspectives, fewer studies have investigated the kinetics of their interactions. Here we review and highlight the type of information that can be gained from kinetic studies. In particular, we show how kinetic studies of coupled folding and binding reactions, an important class of signaling event, are needed to determine mechanisms.This work was supported by the Wellcome Trust (WT 095195MA). M.D.C. is supported by a BBSRC studentship; L.D. by an EPSRC studentship B.I.M.W. by the Cambridge Trust. JC is a Senior Wellcome Trust Research Fellow.This is the final version of the article. It first appeared from the American Society for Biochemistry and Molecular Biology via https://doi.org/10.1074/jbc.R115.69271

Extrinsic conditions influence the self-association and structure of IF1, the regulatory protein of mitochondrial ATP synthase.

The endogenous inhibitor of ATP synthase in mitochondria, called IF1, conserves cellular energy when the proton-motive force collapses by inhibiting ATP hydrolysis. Around neutrality, the 84-amino-acid bovine IF1 is thought to self-assemble into active dimers and, under alkaline conditions, into inactive tetramers and higher oligomers. Dimerization is mediated by formation of an antiparallel α-helical coiled-coil involving residues 44-84. The inhibitory region of each monomer from residues 1-46 is largely α-helical in crystals, but disordered in solution. The formation of the inhibited enzyme complex requires the hydrolysis of two ATP molecules, and in the complex the disordered region from residues 8-13 is extended and is followed by an α-helix from residues 14-18 and a longer α-helix from residue 21, which continues unbroken into the coiled-coil region. From residues 21-46, the long α-helix binds to other α-helices in the C-terminal region of predominantly one of the β-subunits in the most closed of the three catalytic interfaces. The definition of the factors that influence the self-association of IF1 is a key to understanding the regulation of its inhibitory properties. Therefore, we investigated the influence of pH and salt-types on the self-association of bovine IF1 and the folding of its unfolded region. We identified the equilibrium between dimers and tetramers as a potential central factor in the in vivo modulation of the inhibitory activity and suggest that the intrinsically disordered region makes its inhibitory potency exquisitely sensitive and responsive to physiological changes that influence the capability of mitochondria to make ATP

Comments on a class of orthogonality relations relevant to fluid-structure interaction

Copyright @ 2011 Springer Science+Business Media B.V

How do African grey parrots (Psittacus erithacus) perform on a delay of gratification task?

Humans and other animals often find it difficult to choose a delayed reward over an immediate one, even when the delay leads to increased pay-offs. Using a visible incremental reward procedure, we tested the ability of three grey parrots to maintain delay of gratification for an increasingly valuable food pay-off. Up to 5 sunflower seeds were placed within the parrot’s reach, one at a time, at a rate of 1 seed per second. When the parrot took a seed the trial was ended and the birds consumed the accumulated seeds. Parrots were first tested in daily sessions of 10 trials and then with single daily trials. For multiple trial sessions, all three parrots showed some limited improvement across 30 sessions. For single trial sessions, only one parrot showed any increase in seed acquisition across trials. This parrot was also able to consistently obtain two or more seeds per trial (across both multiple and single trial conditions) but was unable to able to wait 5 seconds to obtain the maximum number of seeds. This parrot was also tested on a slower rate of seed presentation, and this significantly reduced her mean seed acquisition in both multiple and single trial conditions, suggesting that both value of reward available and delay duration impact upon self-control. Further manipulation of both the visibility and proximity of seeds during delay maintenance had little impact upon tolerance of delays for both parrots tested in this condition. This task demanded not just a choice of delayed reward but the maintenance of delayed gratification and was clearly difficult for the parrots to learn; additional training or alternative paradigms are required to better understand the capacity for self-control in this species

Ovarian cancer symptom awareness and anticipated delayed presentation in a population sample

Background: While ovarian cancer is recognised as having identifiable early symptoms, understanding of the key determinants of symptom awareness and early presentation is limited. A population-based survey of ovarian cancer awareness and anticipated delayed presentation with symptoms was conducted as part of the International Cancer Benchmarking Partnership (ICBP). Methods: Women aged over 50 years were recruited using random probability sampling (n = 1043). Computer-assisted telephone interviews were used to administer measures including ovarian cancer symptom recognition, anticipated time to presentation with ovarian symptoms, health beliefs (perceived risk, perceived benefits/barriers to early presentation, confidence in symptom detection, ovarian cancer worry), and demographic variables. Logistic regression analysis was used to identify the contribution of independent variables to anticipated presentation (categorised as < 3 weeks or ≥ 3 weeks). Results: The most well-recognised symptoms of ovarian cancer were post-menopausal bleeding (87.4%), and persistent pelvic (79.0%) and abdominal (85.0%) pain. Symptoms associated with eating difficulties and changes in bladder/bowel habits were recognised by less than half the sample. Lower symptom awareness was significantly associated with older age (p ≤ 0.001), being single (p ≤ 0.001), lower education (p ≤ 0.01), and lack of personal experience of ovarian cancer (p ≤ 0.01). The odds of anticipating a delay in time to presentation of ≥ 3 weeks were significantly increased in women educated to degree level (OR = 2.64, 95% CI 1.61 – 4.33, p ≤ 0.001), women who reported more practical barriers (OR = 1.60, 95% CI 1.34 – 1.91, p ≤ 0.001) and more emotional barriers (OR = 1.21, 95% CI 1.06 – 1.40, p ≤ 0.01), and those less confident in symptom detection (OR = 0.56, 95% CI 0.42 – 0.73, p ≤ 0.001), but not in those who reported lower symptom awareness (OR = 0.99, 95% CI 0.91 – 1.07, p = 0.74). Conclusions: Many symptoms of ovarian cancer are not well-recognised by women in the general population. Evidence-based interventions are needed not only to improve public awareness but also to overcome the barriers to recognising and acting on ovarian symptoms, if delays in presentation are to be minimised

Invasive Lionfish Drive Atlantic Coral Reef Fish Declines

Indo-Pacific lionfish (Pterois volitans and P. miles) have spread swiftly across the Western Atlantic, producing a marine predator invasion of unparalleled speed and magnitude. There is growing concern that lionfish will affect the structure and function of invaded marine ecosystems, however detrimental impacts on natural communities have yet to be measured. Here we document the response of native fish communities to predation by lionfish populations on nine coral reefs off New Providence Island, Bahamas. We assessed lionfish diet through stomach contents analysis, and quantified changes in fish biomass through visual surveys of lionfish and native fishes at the sites over time. Lionfish abundance increased rapidly between 2004 and 2010, by which time lionfish comprised nearly 40% of the total predator biomass in the system. The increase in lionfish abundance coincided with a 65% decline in the biomass of the lionfish's 42 Atlantic prey fishes in just two years. Without prompt action to control increasing lionfish populations, similar effects across the region may have long-term negative implications for the structure of Atlantic marine communities, as well as the societies and economies that depend on them

Survival of Influenza A(H1N1) on Materials Found in Households: Implications for Infection Control

The majority of influenza transmission occurs in homes, schools and workplaces, where many frequently touched communal items are situated. However the importance of transmission via fomites is unclear since few data exist on the survival of virus on commonly touched surfaces. We therefore measured the viability over time of two H1N1 influenza strains applied to a variety of materials commonly found in households and workplaces.Influenza A/PuertoRico/8/34 (PR8) or A/Cambridge/AHO4/2009 (pandemic H1N1) viruses were inoculated onto a wide range of surfaces used in home and work environments, then sampled at set times following incubation at stabilised temperature and humidity. Virus genome was measured by RT-PCR; plaque assay (for PR8) or fluorescent focus formation (for pandemic H1N1) was used to assess the survival of viable virus.The genome of either virus could be detected on most surfaces 24 h after application with relatively little drop in copy number, with the exception of unsealed wood surfaces. In contrast, virus viability dropped much more rapidly. Live virus was recovered from most surfaces tested four hours after application and from some non-porous materials after nine hours, but had fallen below the level of detection from all surfaces at 24 h. We conclude that influenza A transmission via fomites is possible but unlikely to occur for long periods after surface contamination (unless re-inoculation occurs). In situations involving a high probability of influenza transmission, our data suggest a hierarchy of priorities for surface decontamination in the multi-surface environments of home and hospitals

A New NO-Releasing Nanoformulation for the Treatment of Pulmonary Arterial Hypertension

Copyright The Author(s) 2016. This article is published with open access at Springerlink.com. Open Access - This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were madePulmonary arterial hypertension (PAH) is a chronic and progressive disease which continues to carry an unacceptably high mortality and morbidity. The nitric oxide (NO) pathway has been implicated in the pathophysiology and progression of the disease. Its extremely short half-life and systemic effects have hampered the clinical use of NO in PAH. In an attempt to circumvent these major limitations, we have developed a new NO-nanomedicine formulation. The formulation was based on hydrogel-like polymeric composite NO-releasing nanoparticles (NO-RP). The kinetics of NO release from the NO-RP showed a peak at about 120 min followed by a sustained release for over 8 h. The NO-RP did not affect the viability or inflammation responses of endothelial cells. The NO-RP produced concentration-dependent relaxations of pulmonary arteries in mice with PAH induced by hypoxia. In conclusion, NO-RP drugs could considerably enhance the therapeutic potential of NO therapy for PAH.Peer reviewedFinal Published versio

Upregulation of CENP-H in tongue cancer correlates with poor prognosis and progression

<p>Abstract</p> <p>Background</p> <p>Centromere protein H (CENP-H) is one of the fundamental components of the human active kinetochore. Recently, CENP-H was identified to be associated with tumorigenesis. This study was aimed to investigate the clinicopathologic significance of CENP-H in tongue cancer.</p> <p>Methods</p> <p>RT-PCR, real time RT-PCR and Western blot were used to examine the expression of CENP-H in tongue cancer cell lines and biopsies. CENP-H protein level in paraffin-embedded tongue cancer tissues were tested by immunohistochemical staining and undergone statistical analysis. CENP-H-knockdown stable cell line was established by infecting cells with a retroviral vector pSuper-retro-CENP-H-siRNA. The biological function of CENP-H was tested by MTT assay, colony formation assay, and Bromodeoxyuridine (BrdU) incorporation assay.</p> <p>Results</p> <p>CENP-H expression was higher in tongue cancer cell lines and cancer tissues (T) than that in normal cell and adjacent noncancerous tongue tissues (N), respectively. It was overexpressed in 55.95% (94/168) of the paraffin-embedded tongue cancer tissues, and there was a strong correlation between CENP-H expression and clinical stage, as well as T classification. CENP-H can predict the prognosis of tongue cancer patients especially those in early stage. Depletion of CENP-H can inhibit the proliferation of tongue cancer cells (Tca8113) and downregulate the expression of Survivin.</p> <p>Conclusion</p> <p>These findings suggested that CENP-H involves in the development and progression of tongue cancer. CENP-H might be a valuable prognostic indicator for tongue cancer patients within early stage.</p