The crystal structure of alanine racemase from Streptococcus pneumoniae, a target for structure-based drug design

<p>Abstract</p> <p>Background</p> <p><it>Streptococcus pneumoniae </it>is a globally important pathogen. The Gram-positive diplococcus is a leading cause of pneumonia, otitis media, bacteremia, and meningitis, and antibiotic resistant strains have become increasingly common over recent years.Alanine racemase is a ubiquitous enzyme among bacteria and provides the essential cell wall precursor, D-alanine. Since it is absent in humans, this enzyme is an attractive target for the development of drugs against <it>S. pneumoniae </it>and other bacterial pathogens.</p> <p>Results</p> <p>Here we report the crystal structure of alanine racemase from <it>S. pneumoniae </it>(Alr_SP). Crystals diffracted to a resolution of 2.0 Å and belong to the space group P3₁21 with the unit cell parameters a = b = 119.97 Å, c = 118.10 Å, α = β = 90° and γ = 120°. Structural comparisons show that Alr_SPshares both an overall fold and key active site residues with other bacterial alanine racemases. The active site cavity is similar to other Gram positive alanine racemases, featuring a restricted but conserved entryway.</p> <p>Conclusions</p> <p>We have solved the structure of Alr_SP, an essential step towards the development of an accurate pharmacophore model of the enzyme, and an important contribution towards our on-going alanine racemase structure-based drug design project. We have identified three regions on the enzyme that could be targeted for inhibitor design, the active site, the dimer interface, and the active site entryway.</p

Are health care professionals able to judge cancer patients' health care preferences correctly? A cross-sectional study

Background: Health care for cancer patients is primarily shaped by health care professionals. This raises the question to what extent health care professionals are aware of patients' preferences, needs and values. The aim of this study was to explore to what extent there is concordance between patients' preferences in cancer care and patients' preferences as estimated by health care professionals. We also examined whether there were gender differences between health care professionals with regard to the degree in which they can estimate patients' preferences correctly. Methods: To obtain unbiased insight into the specific preferences of cancer patients, we developed the 'Cancer patients' health care preferences' questionnaire'. With this questionnaire we assessed a large sample of cancer patients (n = 386). Next, we asked health care professionals (medical oncologists, nurses and policymakers, n = 60) to fill out this questionnaire and to indicate preferences they thought cancer patients would have. Mean scores between groups were compared using Mann-Whitney tests. Effect sizes (ESs) were calculated for statistically significant differences. Results: We found significant differences (ESs 0.31 to 0.90) between patients and professionals for eight out of twenty-one scales and two out of eight single items. Patients valued care aspects related to expertise and attitude of health care providers and accessibility of services as more important than the professionals thought they would do. Health care professionals overestimated the value that patients set on particularly organisational and environmental aspects. We found significant gender-related differences between the professionals (ESs 0.69 to 1.39) for eight out of twenty-one scales and two out of eight single items. When there were significant differences between male and female healthcare professionals in their estimation of patients health care preferences, female health care professionals invariably had higher scores. Generally, female health care professionals did not estimate patients' preferences and needs better than their male colleagues. Conclusions: Health care professionals are reasonably well able to make a correct estimation of patients preferences, but they should be aware of their own bias and use additional resources to gain a better understanding of patients' specific preferences for each patient is different and ultimately the care needs and preferences will also be unique to the person

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

New Zealand glowworm (Arachnocampa luminosa) bioluminescence is produced by a firefly-like luciferase but an entirely new luciferin

Abstract The New Zealand glowworm, Arachnocampa luminosa, is well-known for displays of blue-green bioluminescence, but details of its bioluminescent chemistry have been elusive. The glowworm is evolutionarily distant from other bioluminescent creatures studied in detail, including the firefly. We have isolated and characterised the molecular components of the glowworm luciferase-luciferin system using chromatography, mass spectrometry and 1H NMR spectroscopy. The purified luciferase enzyme is in the same protein family as firefly luciferase (31% sequence identity). However, the luciferin substrate of this enzyme is produced from xanthurenic acid and tyrosine, and is entirely different to that of the firefly and known luciferins of other glowing creatures. A candidate luciferin structure is proposed, which needs to be confirmed by chemical synthesis and bioluminescence assays. These findings show that luciferases can evolve independently from the same family of enzymes to produce light using structurally different luciferins

Crystallization of a protein using dehydration without a precipitant

Crystals grown by simple dehydration from a solution of hypoxic response protein I (HRPI) from M. tuberculosis diffract to a maximum resolution of 2.1 

Neutralizing TIMP1 Restores Fecundity in a Rat Model of Endometriosis and Treating Control Rats with TIMP1 Causes Anomalies in Ovarian Function and Embryo Development1

Human and rat endometriotic lesions synthesize and secrete tissue inhibitor of metalloproteinase 1 (TIMP1). More TIMP1 localizes in the ovarian theca in an established rat model for endometriosis (Endo) when compared to surgical controls (Sham). We hypothesized that endometriotic TIMP1 secreted into peritoneal fluid (PF) negatively affects ovarian function and embryogenesis by altering the balance of matrix metalloproteinases (MMPs) and TIMPs. Three experiments were performed modulating TIMP1 in vitro and in vivo to investigate ovarian and embryonic anomalies. The first experiment demonstrated control embryos treated in vitro with endometriotic PF concentrations of TIMP1 developed abnormally. In the second experiment where TIMP1 was modulated in vivo, TIMP1-treated Sham rats had fewer zygotes, ovarian follicles, and corpora lutea (CLs) and poorer embryo quality and development, which is analogous to the findings in Endo rats. Importantly, Endo rats treated with a TIMP1 function-blocking antibody had zygote, follicle, and CL numbers and embryo quality similar to Sham rats. In addition, more TIMP1 inhibitory activity was found in ovaries from Endo and TIMP1-treated Sham rats than in ovaries from Sham or TIMP1 antibody-treated Endo rats. In experiment three, control rats (no surgery) treated with Endo PF had fewer follicles and CLs and increased TIMP1 localization in the ovarian theca whereas treatment with Endo PF stripped of TIMP1 or with Sham PF had no effect, providing further evidence that endometriotic TIMP1 sequesters in the ovary and inhibits MMPs necessary for ovulation. Collectively, these results showed that excessive TIMP1 was deleterious to ovulation and embryo development. Thus, novel TIMP1-modulating therapies may be developed to alleviate infertility in women with endometriosis