Expanding our knowledge of protein tyrosine phosphatase-like phytases : mechanism, substrate specificity and pathways of myo-inositol hexakisphosphate dephosphorylation

x, 138 leaves ; 29 cm.A novel bacterial protein tyrosine phosphatase (PTP)-like enzyme has recently been isolated that has a PTP-like active site and fold and the ability to dephosphorylate myo-inositol hexakisphosphate. In order to expand our knowledge of this novel class of enzyme, four new representative genes were cloned from 3 different anaerobic bacteria related to clostridia and the recombinant gene products were examined. A combination of site-directed mutagenesis, kinetic, and high-performance ion-pair chromatography studies were used to elucidate the mechanism of hydrolysis, substrate specificity, and pathways of Ins P6 dephosphorylation. The data indicate that these enzymes follow a classical PTP mechanism of hydrolysis and have a general specificity for polyphosphorylated myo-inositol substrates. These enzymes dephosphorylate Ins P6 in a distributive manner, and have the most highly ordered pathways of sequential dephosphorylation of InsP6 characterized to date. Bioinformatic analyses have indicated homologues that are involved in the regulation of cellular function

Kinetic and structural analysis of a bacterial protein tyrosine phosphatase-like myo-inositol polyphosphatase. Protein Sci

Abstract PhyA from Selenomonas ruminantium (PhyAsr), is a bacterial protein tyrosine phosphatase (PTP)-like inositol polyphosphate phosphatase (IPPase) that is distantly related to known PTPs. PhyAsr has a second substrate binding site referred to as a standby site and the P-loop (HCX 5 R) has been observed in both open (inactive) and closed (active) conformations. Site-directed mutagenesis and kinetic and structural studies indicate PhyAsr follows a classical PTP mechanism of hydrolysis and has a broad specificity toward polyphosphorylated myo-inositol substrates, including phosphoinositides. Kinetic and molecular docking experiments demonstrate PhyAsr preferentially cleaves the 3-phosphate position of Ins P 6 and will produce Ins(2)P via a highly ordered series of sequential dephosphorylations: D-Ins(1,2,4,5,6)P 5 , Ins(2,4,5,6)P 4 , D-Ins(2,4,5)P 3 , and D-Ins(2,4)P 2 . The data support a distributive enzyme mechanism and suggest the PhyAsr standby site is involved in the recruitment of substrate. Structural studies at physiological pH and high salt concentrations demonstrate the ''closed'' or active P-loop conformation can be induced in the absence of substrate. These results suggest PhyAsr should be reclassified as a D-3 myo-inositol hexakisphosphate phosphohydrolase and suggest the PhyAsr reaction mechanism is more similar to that of PTPs than previously suspected. Keywords: inositol polyphosphate phosphatase; protein tyrosine phosphatase; phosphoinositide phosphatase; phytase; myo-inositol; P-loop; hydrolysis pathway Supplemental material: see www.proteinscience.org Protein tyrosine phosphatase (PTP) superfamily enzymes have been discovered in a range of prokaryotes, and most appear to serve roles that mimic their better-known eukaryotic counterparts as regulators of cellular function The X-ray crystallographic structure of PhyAsr Article published online ahead of print. Article and publication date are at http://www.proteinscience.org/cg

An Examination of the Observed Placebo Effect Associated with the Treatment of Low Back Pain – A Systematic Review

OBJECTIVE: To determine whether the nonspecific effects that occur following the use of sham interventions to treat nonspecific low back pain (LBP) are large enough to be considered clinically meaningful

Associations between demographics and clinical ideology, beliefs, and practice patterns: a secondary analysis of a survey of randomly sampled United States chiropractors

Abstract Background The chiropractic profession in the United States (US) has a long history of intra-professional discourse surrounding ideology and beliefs. Large-scale efforts have evaluated 3 distinctive subgroups of US chiropractors focused on these areas of practice: spine/neuromusculoskeletal, primary care, and vertebral subluxation. To our knowledge, there have not been any prior studies exploring the factors associated with these ideology and belief characteristics of these subgroups. The purpose of this study was to explore, describe, and characterize the association of US chiropractors’ ideology, beliefs, and practice patterns with: 1) chiropractic degree program of graduation, 2) years since completion of chiropractic degree, and 3) US geographic region of primary practice. Methods This was a secondary analysis of a cross-sectional survey of a random sample of US licensed chiropractors (n = 8975). A 10% random sample was extracted from each of the 50 states and District of Columbia chiropractic regulatory board lists. The survey was conducted between March 2018-January 2020. The survey instrument consisted of 7 items that were developed to elicit these differentiating ideologies, beliefs, and practice patterns: 1) clinical examination/assessment, 2) health conditions treated, 3) role of chiropractors in the healthcare system, 4) the impact of chiropractic adjustments [spinal manipulation] in treating patients with cancer, 5) vaccination attitudes, 6) detection of subluxation on x-ray, and 7) x-ray utilization rates. Multinomial regression was used to analyze associations between these 7 ideology and practice characteristic items from the survey (dependent variables) and the 3 demographic items listed above (independent variables). Results Data from 3538 respondents (74.6% male) were collected with an overall response rate of 39.4%. Patterns of responses to the 7 survey items for ideologies, beliefs, and practice characteristics were significantly different based on chiropractic degree program of graduation, years since completion of chiropractic degree, and geographic region of primary practice. Conclusions Among US chiropractors, chiropractic program of graduation, years since completion of chiropractic degree, and geographic region of primary practice are associated with variations in clinical ideology, beliefs, and practice patterns. The wide variation and inconsistent beliefs of US chiropractors could result in public confusion and impede interprofessional integration

Recommendations for the development, implementation, and reporting of control interventions in efficacy and mechanistic trials of physical, psychological, and self-management therapies: the CoPPS Statement

Control interventions (often called “sham,” “placebo,” or “attention controls”) are essential for studying the efficacy or mechanism of physical, psychological, and self-management interventions in clinical trials. This article presents core recommendations for designing, conducting, and reporting control interventions to establish a quality standard in non-pharmacological intervention research. A framework of additional considerations supports researchers’ decision making in this context. We also provide a reporting checklist for control interventions to enhance research transparency, usefulness, and rigour