The \u3cem\u3edapE\u3c/em\u3e-encoded \u3cem\u3eN\u3c/em\u3e-Succinyl-l,l-Diaminopimelic Acid Desuccinylase from \u3cem\u3eHaemophilus influenzae\u3c/em\u3e Is a Dinuclear Metallohydrolase

The Zn K-edge extended X-ray absorption fine structure (EXAFS) spectra, of the dapE-encoded N-succinyl-l,l-diaminopimelic acid desuccinylase (DapE) from Haemophilus influenzae have been recorded in the presence of one or two equivalents of Zn(II) (i.e. [Zn_(DapE)] and [ZnZn(DapE)]). The Fourier transforms of the Zn EXAFS are dominated by a peak at ca. 2.0 Å, which can be fit for both [Zn_(DapE)] and [ZnZn(DapE)], assuming ca. 5 (N,O) scatterers at 1.96 and 1.98 Å, respectively. A second-shell feature at ca. 3.34 Å appears in the [ZnZn(DapE)] EXAFS spectrum but is significantly diminished in [Zn_(DapE)]. These data show that DapE contains a dinuclear Zn(II) active site. Since no X-ray crystallographic data are available for any DapE enzyme, these data provide the first glimpse at the active site of DapE enzymes. In addition, the EXAFS data for DapE incubated with two competitive inhibitors, 2-carboxyethylphosphonic acid and 5-mercaptopentanoic acid, are also presented

Structural Evidence That the Methionyl Aminopeptidase from \u3cem\u3eEscherichia coli\u3c/em\u3e Is a Mononuclear Metalloprotease

The Co and Fe K-edge extended X-ray absorption fine structure (EXAFS) spectra of the methionyl aminopeptidase from Escherichia coli (EcMetAP) have been recorded in the presence of 1 and 2 equiv of either Co(II) or Fe(II) (i.e., [Co(II)_(EcMetAP)], [Co(II)Co(II)(EcMetAP)], [Fe(II)_(EcMetAP)], and [Fe(II)Fe(II)(EcMetAP)]). The Fourier transformed data of both [Co(II)_(EcMetAP)] and [Co(II)Co(II)(EcMetAP)] are dominated by a peak at ca. 2.05 Å, which can be fit assuming 5 light atom (N,O) scatterers at 2.04 Å. Attempts to include a Co−Co interaction (in the 2.4−4.0 Å range) in the curve-fitting parameters were unsuccessful. Inclusion of multiple-scattering contributions from the outer-shell atoms of a histidine−imidazole ring resulted in reasonable Debye−Waller factors for these contributions and a slight reduction in the goodness-of-fit value (f ‘). These data suggest that a dinuclear Co(II) center does not exist in EcMetAP and that the first Co atom is located in the histidine-ligated side of the active site. The EXAFS data obtained for [Fe(II)_(EcMetAP)] and [Fe(II)Fe(II)(EcMetAP)] indicate that Fe(II) binds to EcMetAP in a similar site to Co(II). Since no X-ray crystallographic data are available for any Fe(II)-substituted EcMetAP enzyme, these data provide the first glimpse at the Fe(II) active site of MetAP enzymes. In addition, the EXAFS data for [Co(II)Co(II)(EcMetAP)] incubated with the antiangiogenesis drug fumagillin are also presented

The Admissions Process in Occupational Therapy Education: Investigating Academic and Non-academic Metrics in the Applicant Selection Process

The overall goal for any admissions process is to analyze criteria and identify the prospective students that have the highest potential for success in the program’s curriculum and in the field as a practicing clinician. The purpose of this study was to examine common academic and non-academic criteria utilized in occupational therapy (OT) admission processes and determine what criteria are used by programs with 100% student pass ratings on their National Board for Certification in Occupational Therapy (NBCOT) exam following completion of an OT program. Admissions criteria components and NBCOT pass rates were collected from the top 107 OT programs, as reported by US News and World Report, using publicly available websites for each program and the NBCOT webpage. Descriptive statistics were recorded regarding the frequency of utilizing various admissions criteria. Chi-square tests were utilized to examine the relationship between each admissions criteria component and the NBCOT pass rate. Admissions criteria frequently utilized by the top OT programs included a bachelor’s degree prior to matriculation (90.99% programs), minimum undergraduate GPA (55.86%), personal statement (90.09%), letters of recommendation (97.30%), observation hours (74.77%), and an interview (61.26%). Few programs required applicants to submit a minimum math/science GPA (11.71%) or a writing sample (40.54%). Results did not reveal a statistically significant difference between analyzed criteria groups. It is likely that NBCOT pass rates are impacted by other factors that were not publicly available or included in this study

The Relationship Between Holistic Admissions Criteria and Program Ranking Among Occupational Therapy Entry-Level Programs

Holistic admissions criteria are one strategy to be more inclusive of students with a variety of experiences, cultures, and beliefs. The purpose of this study is to evaluate the relationship between holistic admissions criteria and occupational therapy program ranking. We used a retrospective cross-sectional cohort descriptive study design of occupational therapy programs in the United States to understand whether top performing programs employ holistic admissions criteria. Secondary descriptive analysis from the top and bottom 50 ranked occupational therapy programs in 2020 U.S. News & World Report (Morse et al., 2020) was completed. We used a nominal scale to classify programs into two groups based on use of holistic measures. Overall, 54.95% (n = 61) of the programs used holistic admissions criteria. Of these, 36 were among the top 50 ranked programs, and 25 were among the bottom 50 ranked schools. Occupational therapy programs using holistic admissions criteria were not statistically different from the programs that did not use holistic admissions criteria on their overall ranking (χ2 = 0.55, p = 0.46). The bottom- and top-ranked programs were not statistically different regarding use of holistic admissions criteria, which suggests that implementation of holistic admission criteria is not associated with program ranking. Therefore, this research should encourage universities to implement holistic admissions criteria, as it is not associated with lowered program ranking, but has been associated with increasing both diversity and academic performance in other health professional programs (Glazer et al., 2014; Witzburg & Sondheimer, 2013; Price & Mills, 2010)

Kinetic and Structural Characterization of Manganese(II)-Loaded Methionyl Aminopeptidases

Manganese(II) activation of the methionyl aminopeptidases from Escherichia coli (EcMetAP-I) and the hyperthermophilic archaeon Pyrococcus furiosus (PfMetAP-II) was investigated. Maximum catalytic activity for both enzymes was obtained with 1 equiv of Mn(II), and the dissociation constants (Kd) for the first metal binding site were found to be 6 ± 0.5 and 1 ± 0.5 μM for EcMetAP-I and PfMetAP-II, respectively. These Kd values were verified by isothermal titration calorimetry (ITC) and found to be 3.0 ± 0.2 and 1.4 ± 0.2 μM for EcMetAP-I and PfMetAP-II, respectively. The hydrolysis of MGMM was measured in triplicate between 25 and 85 °C at eight substrate concentrations ranging from 2 to 20 mM for PfMetAP-II. Both specific activity and Km values increased with increasing temperature. An Arrhenius plot was constructed from the kcat values and was found to be linear over the temperature range 25−85 °C. The activation energy for the Mn(II)-loaded PfMetAP-II hydrolysis of MGMM was found to be 25.7 kJ/mol while the remaining thermodynamic parameters calculated at 25 °C are ΔG⧧ = 50.1 kJ/mol, ΔH⧧ = 23.2 kJ/mol, and ΔS⧧ = −90.2 J·mol-1·K-1

Sexual dimorphism in cancer.

The incidence of many types of cancer arising in organs with non-reproductive functions is significantly higher in male populations than in female populations, with associated differences in survival. Occupational and/or behavioural factors are well-known underlying determinants. However, cellular and molecular differences between the two sexes are also likely to be important. In this Opinion article, we focus on the complex interplay that sex hormones and sex chromosomes can have in intrinsic control of cancer-initiating cell populations, the tumour microenvironment and systemic determinants of cancer development, such as the immune system and metabolism. A better appreciation of these differences between the two sexes could be of substantial value for cancer prevention as well as treatment

Structural elements of metal selectivity in metal sensor proteins

Staphylococcus aureus CzrA and Mycobacterium tuberculosis NmtR are homologous zinc/cobalt-responsive and nickel/cobalt-responsive transcriptional repressors in vivo, respectively, and members of the ArsR/SmtB superfamily of prokaryotic metal sensor proteins. We show here that Zn(II) is the most potent negative allosteric regulator of czr operator/promoter binding in vitro with the trend Zn(II)>Co(II)≫Ni(II), whereas the opposite holds for the binding of NmtR to the nmt operator/promoter, Ni(II)>Co(II)>Zn(II). Characterization of the metal coordination complexes of CzrA and NmtR by UV/visible and x-ray absorption spectroscopies reveals that metals that form four-coordinate tetrahedral complexes with CzrA [Zn(II) and Co(II)] are potent regulators of DNA binding, whereas metals that form five- or six-coordinate complexes with NmtR [Ni(II) and Co(II)] are the strongest allosteric regulators in this system. Strikingly, the Zn(II) coordination complexes of CzrA and NmtR cannot be distinguished from one another by x-ray absorption spectroscopy, with the best fit a His-3-carboxylate complex in both cases. Inspection of the primary structures of CzrA and NmtR, coupled with previous functional data, suggests that three conserved His and one Asp from the C-terminal α5 helix donate ligands to create a four-coordinate complex in both CzrA and NmtR, with NmtR uniquely capable of expanding its coordination number in the Ni(II) and Co(II) complexes by recruiting additional His ligands from a C-terminal extension of the α5 helix

A combined computational and experimental investigation of the [2Fe–2S] cluster in biotin synthase

Biotin synthase was the first example of what is now regarded as a distinctive enzyme class within the radical S-adenosylmethionine superfamily, the members of which use Fe/S clusters as the sulphur source in radical sulphur insertion reactions. The crystal structure showed that this enzyme contains a [2Fe–2S] cluster with a highly unusual arginine ligand, besides three normal cysteine ligands. However, the crystal structure is at such a low resolution that neither the exact coordination mode nor the role of this exceptional ligand has been elucidated yet, although it has been shown that it is not essential for enzyme activity. We have used quantum refinement of the crystal structure and combined quantum mechanical and molecular mechanical calculations to explore possible coordination modes and their influences on cluster properties. The investigations show that the protonation state of the arginine ligand has little influence on cluster geometry, so even a positively charged guanidinium moiety would be in close proximity to the iron atom. Nevertheless, the crystallised enzyme most probably contains a deprotonated (neutral) arginine coordinating via the NH group. Furthermore, the Fe···Fe distance seems to be independent of the coordination mode and is in perfect agreement with distances in other structurally characterised [2Fe–2S] clusters. The exceptionally large Fe···Fe distance found in the crystal structure could not be reproduced

Harmful algal blooms and eutrophication : examining linkages from selected coastal regions of the United States

Author Posting. © Elsevier B.V., 2008. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Harmful Algae 8 (2008): 39-53, doi:10.1016/j.hal.2008.08.017.Coastal waters of the United States (U.S.) are subject to many of the major harmful algal bloom (HAB) poisoning syndromes and impacts. These include paralytic shellfish poisoning (PSP), neurotoxic shellfish poisoning (NSP), amnesic shellfish poisoning (ASP), ciguatera fish poisoning (CFP) and various other HAB phenomena such as fish kills, loss of submerged vegetation, shellfish mortalities, and widespread marine mammal mortalities. Here, the occurrences of selected HABs in a selected set of regions are described in terms of their relationship to eutrophication, illustrating a range of responses. Evidence suggestive of changes in the frequency, extent or magnitude of HABs in these areas is explored in the context of the nutrient sources underlying those blooms, both natural and anthropogenic. In some regions of the U.S., the linkages between HABs and eutrophication are clear and well documented, whereas in others, information is limited, thereby highlighting important areas for further research.Support was provided through the Woods Hole Center for Oceans and Human Health (to DMA), National Science Foundation (NSF) grants OCE-9808173 and OCE-0430724 (to DMA), OCE-0234587 (to WPC), OCE04-32479 (to MLP), OCE-0138544 (to RMK), OCE-9981617 (to PMG); National Institute of Environmental Health Sciences (NIEHS) grants P50ES012742-01 (to DMA) and P50ES012740 (to MLP); NOAA Grants NA96OP0099 (to DMA), NA16OP1450 (to VLT), NA96P00084 (to GAV and CAH), NA160C2936 and NA108H-C (to RMK), NA860P0493 and NA04NOS4780241 (to PMG), NA04NOS4780239-02 (to RMK), NA06NOS4780245 (to DWT). Support was also provided from the West Coast Center for Oceans and Human Health (to VLT and WPC), USEPA Grant CR826792-01-0 (to GAV and CAH), and the State of Florida Grant S7701617826 (to GAV and CAH)