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BioAutoMATED: An end-to-end automated machine learning tool for explanation and design of biological sequences. Cell Syst 2023; 14:525-542.e9. [PMID: 37348466 PMCID: PMC10700034 DOI: 10.1016/j.cels.2023.05.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 02/17/2023] [Accepted: 05/22/2023] [Indexed: 06/24/2023]
Abstract
The design choices underlying machine-learning (ML) models present important barriers to entry for many biologists who aim to incorporate ML in their research. Automated machine-learning (AutoML) algorithms can address many challenges that come with applying ML to the life sciences. However, these algorithms are rarely used in systems and synthetic biology studies because they typically do not explicitly handle biological sequences (e.g., nucleotide, amino acid, or glycan sequences) and cannot be easily compared with other AutoML algorithms. Here, we present BioAutoMATED, an AutoML platform for biological sequence analysis that integrates multiple AutoML methods into a unified framework. Users are automatically provided with relevant techniques for analyzing, interpreting, and designing biological sequences. BioAutoMATED predicts gene regulation, peptide-drug interactions, and glycan annotation, and designs optimized synthetic biology components, revealing salient sequence characteristics. By automating sequence modeling, BioAutoMATED allows life scientists to incorporate ML more readily into their work.
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Abstract 5001: Identification of a Six2/Sox2/Nanog stem cell axis that promotes breast cancer metastatic colonization. Cancer Res 2018. [DOI: 10.1158/1538-7445.am2018-5001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Although significant progress has been made in understanding the molecular mechanisms that lead to metastatic breast cancer, it remains the overwhelming cause of death for patients. Current studies primarily focus on the prevention of early stages of metastasis, such as migration and invasion. But at the time of diagnosis tumor cells have likely left the primary tumor, suggesting that inhibition of the early stages of metastasis may not be the most effective means of inhibiting metastatic burden. Instead, the identification and targeting of molecules required for establishment and survival of cells at secondary sites is imperative for advancing therapies. We are examining the role of the developmental transcription factor Six2 in promoting metastatic burden. Six2 is a member of the Six family of transcription factors and is responsible for the maintenance of stem/progenitor cells during nephrogenesis. Using knockdown (KD) and overexpression (OE) models in murine mammary cells, we demonstrated that Six2 promotes specifically late-stage metastasis (growth at the secondary site). RNA-Seq analysis on control and Six2 OE cells showed a dramatic enrichment in stem cell transcriptional programs downstream of Six2 in mammary/breast cancer cells. Flow cytometry analyses and tumorsphere assays demonstrate that Six2 OE leads to an increase, whereas Six2 KD leads to a decrease, in the mammary stem cell population and tumorsphere formation, respectively. Using an immune competent mouse model, in vivo orthotopic limiting-dilution experiments reveal that Six2 regulates tumor initiation. In addition, we show that Six2 regulates late-stage metastasis of human breast cancer cells in vivo, as measured by metastatic burden after tail vein injection. Thus, our data demonstrate that Six2 similarly promotes stem phenotypes in breast cancer cells as it does during kidney development, and suggest that this attribute may be critical for its ability to promote metastatic outgrowth. To determine the molecular mechanism by which Six2 mediates stem phenotypes and metastasis in breast cancer, we interrogated our RNA-seq data, which suggested that Six2 may control master regulators of stemness. We demonstrate that both Sox2 and Nanog are regulated by Six2. In human breast cancer gene expression datasets, Six2 significantly positively correlates with both Sox2 and Nanog, and combined OE of Six2 with either Sox2 or Nanog results in poor prognosis. Preliminary data suggest that loss of Sox2 downstream of Six2 inhibits metastatic outgrowth, and that Sox2 is upstream of Nanog in the pathway. Together, our data demonstrate that Six2 regulates cancer stem phenotypes to promote metastatic outgrowth, uncovering a novel Six2/Sox2/Nanog axis that is critical for metastatic colonization.
Citation Format: Michael U. Oliphant, Ahwan Pandey, Katherine Johnson, Rani Powers, Matthew Galbraith, James Costello, Heide L. Ford. Identification of a Six2/Sox2/Nanog stem cell axis that promotes breast cancer metastatic colonization [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5001.
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Abstract 4332: Meta-analysis of molecular features associated with aggressive prostate cancer. Cancer Res 2018. [DOI: 10.1158/1538-7445.am2018-4332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
The TMPRSS2:ERG fusion is the most common genomic alteration in prostate cancer, occurring in 40-50% of primary tumors. The frequency of the ERG fusion remains between 40-50% in metastatic tumors, supporting previous findings that the fusion can drive tumor development, but is not sufficient to drive aggressive, lethal disease. Large -omic datasets collected over thousands of patient tumors, such as The Cancer Genome Atlas (TCGA), paired with outcomes present the raw data needed to associate genetic aberrations with markers of aggressive disease. Accordingly, we performed a meta-analysis of over 2,000 patient samples to identify combinations of -omic features associated with aggressive ERG fusion-positive and ERG fusion-negative prostate cancer. The data were collected from 8 independent, publicly available prostate cancer cohorts and cover range of disease phenotypes (e.g., neuroendocrine, castration resistance). Our analysis consisted of training univariate Cox regression models separately for single genomic or pairs of genomic features within each independent dataset. Based on the availability, we explored gene expression, mutation, and copy number alterations, all used to build separate models. We then combined models for a genomic feature across all datasets by weighting individual coefficients by the inverse of their squared error in a fixed effects model; final results are reported as corrected p-values. We compared and contrasted results from combined models within data type (i.e., only gene expression) to models integrating multiple data types. Interestingly, we find that the genomic features associated with aggressive disease differed based on ERG status. We report genomic loci that are altered in all patients, but associate with aggressive disease only in patients with an ERG fusion. We also report loci that co-occur or are mutually exclusive of the ERG fusion and associated with aggressiveness. For example, SPOP mutations are known to be mutually exclusive of ERG fusions. We report a finer stratification of patients with SPOP mutations based on biochemical relapse. Our results present a compressive meta-analysis of molecular features in prostate cancer and identify novel molecular subtypes associated with aggressive disease.
Citation Format: James C. Costello, Rani Powers, Andrew Goodspeed, Scott D. Cramer. Meta-analysis of molecular features associated with aggressive prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4332.
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ABBV-085 is a novel antibody–drug conjugate (ADC) that targets LRRC15 in the tumor microenvironment. Eur J Cancer 2016. [DOI: 10.1016/s0959-8049(16)32622-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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OS075. Endothelial-dependent vascular function is significantly impaired in obesity and restored by overexpression of DDAH1: Evidence for the role of ADMA. Pregnancy Hypertens 2012; 2:218. [DOI: 10.1016/j.preghy.2012.04.076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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6
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Dial-a-size: Precision quantum dot nanopatterning using cheap, off-the-shelf copolymers. J Appl Polym Sci 2008. [DOI: 10.1002/app.27268] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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P-121. Fertil Steril 2006. [DOI: 10.1016/j.fertnstert.2006.07.467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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P-490. Fertil Steril 2006. [DOI: 10.1016/j.fertnstert.2006.07.854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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P-666. Fertil Steril 2006. [DOI: 10.1016/j.fertnstert.2006.07.1045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Abstract
The authors present two cases that provide the first autopsy findings in multifocal acquired demyelinating sensory and motor neuropathy (MADSAMN). Both cases documented multifocal but asymmetric demyelinating neuropathy with rare axonal degeneration. One case clearly documented an inflammatory polyradiculoplexoneuropathy, confirming the inflammatory nature of this neuropathy. This study showed that MADSAMN is an inflammatory demyelinating polyradiculoneuropathy that shares histologic features observed in chronic inflammatory demyelinating polyradiculoneuropathy and multifocal motor neuropathy (MMN), suggesting a similar immunopathogenesis for these entities.
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Analysis of Failed Fertilization in IVF and ICSI Patients Using the DNA Specific Stain Hoechst 33342. Fertil Steril 2005. [DOI: 10.1016/j.fertnstert.2005.07.736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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12
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Identification and validation of anti-TMEFF2-Auristatin E conjugated antibodies in the treatment of prostate cancer. J Clin Oncol 2004. [DOI: 10.1200/jco.2004.22.90140.2557] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Cholera on the plains: the epidemic of 1867 in Kansas. THE KANSAS HISTORICAL QUARTERLY 2001; 37:351-93. [PMID: 11632436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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14
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Maintaining temperature in IVF culture dishes: do aluminum warming blocks reduce the rate of cooling? Fertil Steril 2001. [DOI: 10.1016/s0015-0282(01)02681-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Abstract
Tumor necrosis factor receptor-1 death domain (TNFR-1 DD) is the intracellular functional domain responsible for the receptor signaling activities. The solution structure of the R347K mutant of TNFR-1 DD was solved by NMR spectroscopy. A total of 20 structures were calculated by means of hybrid distance geometry-simulated annealing using a total of 1167 distance constraints and 117 torsion angle constraints. The atomic rms distribution about the mean coordinate positions for the 20 structures for residues composing the secondary structure region is 0.40 A for the backbone atoms and 1.09 A for all atoms. The structure consists of six antiparallel alpha-helices arranged in a similar fashion to the other members of the death domain superfamily. The secondary structure and three-dimensional structure of R347K TNFR1-DD are very similar to the secondary structure and deduced topology of the R347A TNFR1-DD mutant. Mutagenesis studies identified critical residues located in alpha2 and part of alpha3 and alpha4 that are crucial for self-interaction and interaction with TRADD. Structural superposition with previously solved proteins in the death domain superfamily reveals that the major differences between the structures reside in alpha2, alpha3, and alpha4. Interestingly, these regions correspond to the binding sites of TNFR1-DD, providing a structural basis for the specificity of death domain interactions and its subsequent signaling event.
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Abstract
Interleukin-13 has been implicated as a key factor in asthma, allergy, atopy and inflammatory response, establishing the protein as a valuable therapeutic target. The high-resolution solution structure of human IL-13 has been determined by multidimensional NMR. The resulting structure is consistent with previous short-chain left-handed four-helix bundles, where a significant similarity in the folding topology between IL-13 and IL-4 was observed. IL-13 shares a significant overlap in biological function with IL-4, a result of the common alpha chain component (IL-4Ralpha) in their respective receptors. Based on the available structural and mutational data, an IL-13/IL-4Ralpha model and a sequential mechanism for forming the signaling heterodimer is proposed for IL-13.
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MESH Headings
- Amino Acid Sequence
- Crystallography, X-Ray
- Dimerization
- Humans
- Interleukin-13/chemistry
- Interleukin-13/genetics
- Interleukin-13/metabolism
- Interleukin-13 Receptor alpha1 Subunit
- Interleukin-4/chemistry
- Interleukin-4/metabolism
- Models, Biological
- Models, Molecular
- Molecular Sequence Data
- Mutation
- Nuclear Magnetic Resonance, Biomolecular
- Protein Structure, Secondary
- Receptors, Interleukin/metabolism
- Receptors, Interleukin-13
- Receptors, Interleukin-4/chemistry
- Receptors, Interleukin-4/genetics
- Receptors, Interleukin-4/metabolism
- Sequence Alignment
- Signal Transduction
- Solutions
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Validity of using the radius of gyration as a restraint in NMR protein structure determination. J Am Chem Soc 2001; 123:3834-5. [PMID: 11457122 DOI: 10.1021/ja005770p] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
BACKGROUND Acyl carrier protein (ACP) is a fundamental component of fatty acid biosynthesis in which the fatty acid chain is elongated by the fatty acid synthetase system while attached to the 4'-phosphopantetheine prosthetic group (4'-PP) of ACP. Activation of ACP is mediated by holo-acyl carrier protein synthase (ACPS) when ACPS transfers the 4'-PP moiety from coenzyme A (CoA) to Ser36 of apo-ACP. Both ACP and ACPS have been identified as essential for E. coli viability and potential targets for development of antibiotics. RESULTS The solution structure of B. subtilis ACP (9 kDa) has been determined using two-dimensional and three-dimensional heteronuclear NMR spectroscopy. A total of 22 structures were calculated by means of hybrid distance geometry-simulated annealing using a total of 1,050 experimental NMR restraints. The atomic rmsd about the mean coordinate positions for the 22 structures is 0.45 +/- 0.08 A for the backbone atoms and 0.93 +/- 0.07 A for all atoms. The overall ACP structure consists of a four alpha-helical bundle in which 4'-PP is attached to the conserved Ser36 that is located in alpha helix II. CONCLUSIONS Structural data were collected for both the apo and holo forms of ACP that suggest that the two forms of ACP are essentially identical. Comparison of the published structures for E. coli ACP and actinorhodin polyketide synthase acyl carrier protein (act apo-ACP) from Streptomyces coelicolor A3(2) with B. subtilis ACP indicates similar secondary structure elements but an extremely large rmsd between the three ACP structures (>4.3 A). The structural difference between B. subtilis ACP and both E. coli and act apo-ACP is not attributed to an inherent difference in the proteins, but is probably a result of a limitation in the methodology available for the analysis for E. coli and act apo-ACP. Comparison of the structure of free ACP with the bound form of ACP in the ACP-ACPS complex reveals a displacement of helix II in the vicinity of Ser36. The induced perturbation of ACP by ACPS positions Ser36 proximal to coenzyme A and aligns the dipole of helix II to initiate transfer of 4'-PP to ACP.
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MS/NMR: a structure-based approach for discovering protein ligands and for drug design by coupling size exclusion chromatography, mass spectrometry, and nuclear magnetic resonance spectroscopy. Anal Chem 2001; 73:571-81. [PMID: 11217765 DOI: 10.1021/ac0006270] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A protocol is described for rapidly screening small organic molecules for their ability to bind a target protein while obtaining structure-related information as part of a structure-based drug discovery and design program. The methodology takes advantage of and combines the inherent strengths of size exclusion gel chromatography, mass spectrometry, and NMR to identify bound complexes in a relatively universal high-throughput screening approach. Size exclusion gel chromatography in the spin column format provides the high-speed separation of a protein-ligand complex from free ligands. The spin column eluent is then analyzed under denaturing conditions by electrospray ionization mass spectrometry (MS) for the presence of small molecular weight compounds formerly bound to the protein. Hits identified by MS are then individually assayed by chemical shift perturbations in a 2D 1H-15N HSQC NMR spectrum to verify specific interactions of the compound with the protein and identification of the binding site on the protein. The utility of the MS/NMR assay is demonstrated with the use of the catalytic fragment of human fibroblast collagenase (MMP-1) as a target protein and the screening of a library consisting of approximately 32 000 compounds for the identification of molecules that exhibit specific binding to the RGS4 protein.
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Abstract
A novel series of anthranilic acid-based inhibitors of MMP-1, MMP-9, and MMP-13 was prepared and evaluated both in vitro and in vivo. The most potent compound, 6e, has in vivo activity in a rat sponge-wrapped cartilage model.
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Evaluation of the utility of NMR structures determined from minimal NOE-based restraints for structure-based drug design, using MMP-1 as an example. Biochemistry 2000; 39:13365-75. [PMID: 11063573 DOI: 10.1021/bi001658s] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The application of deuterium labeling and residual dipolar coupling constants in combination with other structural information has demonstrated the potential for significantly expanding the range of viable protein targets for structural analysis by NMR. A previous study by Clore et al. [(1999) J. Am. Chem. Soc. 121, 6513-6514] demonstrated that a significant improvement in the overall protein structure occurs with the combination of residual dipolar coupling constants and minimal tertiary long-range distance restraints. The analysis of NMR protein structures determined with minimal structural information is extended with a particular interest in the utility of these structures for a structure-based drug design program. As an example, the catalytic fragment of human fibroblast collagenase (MMP-1) was used to follow the effect of minimal restraint sets on the protein structure and its utility in drug design with a particular interest in the effect on the active site conformation. An MMP-1 structure that was calculated with the maximal number of restraints attainable with the constraint of a deuterated protein was shown to be very similar to a high-quality MMP-1 structure that was calculated from a complete set of restraints. The superposition of the active site backbone atoms for the high-quality and minimal restraint MMP-1 structures yielded an rmsd of 0.68 A where the size and shape of the S1' pocket are nearly identical. Additionally, an MMP-1-CGS-27023A complex based on a minimal set of NOE-based restraints reliably reproduced the structure of the complex, establishing the usefulness of the structures for drug design.
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Abstract
OBJECTIVE The objective of this study was to determine the exposure of premature infants to lead from blood transfusions. STUDY DESIGN Blood lead concentrations were determined for 19 very premature infants at the time of admission, at 4 weeks of life, and before and after transfusions and in the donor packed red blood cells of 79 transfusions. RESULTS The number of transfusions per patient was 4. 2 +/- 2.8 (mean +/- SD) with 15.7 +/- 1.9 mL/kg packed red blood cells for a lead dose of 1.56 +/- 1.77 microg/dL. The total dose of lead from these transfusions over the 4-week period was 4.0 +/- 2.8 microg/kg (range, 0.9-10.6 microg/kg). Increases in post-transfusion blood lead concentration were linear with doses higher than 1.5 microg/dL. Packed red blood cells with a blood lead concentration of > or = 5 microg/dL resulted in an elevated post-transfusion blood lead concentration in some infants. CONCLUSIONS The lead exposure to these infants through blood transfusion exceeds the acceptable daily intake values for lead and may result in unacceptably high post-transfusion blood lead concentrations. Use of packed red blood cells with lead concentrations <3.3 microg/dL is one cost-effective means to reduce exposure.
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High-resolution solution structure of the catalytic fragment of human collagenase-3 (MMP-13) complexed with a hydroxamic acid inhibitor. J Mol Biol 2000; 302:671-89. [PMID: 10986126 DOI: 10.1006/jmbi.2000.4082] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The high-resolution solution structure of the catalytic fragment of human collagenase-3 (MMP-13) complexed with a sulfonamide derivative of a hydroxamic acid compound (WAY-151693) has been determined by multidimensional heteronuclear NMR. A total of 30 structures were calculated for residues 7-164 by means of hybrid distance geometry-simulated annealing using a total of 3280 experimental NMR restraints. The atomic rms distribution about the mean coordinate positions for the 30 structures is 0.43(+/-0.05) A for the backbone atoms, 0.80(+/-0.09) A for all atoms, and 0.47(+/-0.04) A for all atoms excluding disordered side-chains. The overall structure of MMP-13 is composed of a beta-sheet consisting of five beta-strands in a mixed parallel and anti-parallel arrangement and three alpha-helices where its overall fold is consistent with previously solved MMP structures. A comparison of the NMR structure of MMP-13 with the published 1.6 A resolution X-ray structure indicates that the major differences between the structures is associated with loop dynamics and crystal-packing interactions. The side-chains of some active-site residues for the NMR and X-ray structures of MMP-13 adopt distinct conformations. This is attributed to the presence of unique inhibitors in the two structures that encounter distinct interactions with MMP-13. The major structural difference observed between the MMP-13 and MMP-1 NMR structures is the relative size and shape of the S1' pocket where this pocket is significantly longer for MMP-13, nearly reaching the surface of the protein. Additionally, MMP-1 and MMP-13 exhibit different dynamic properties for the active-site loop and the structural Zn-binding region. The inhibitor WAY-151693 is well defined in the MMP-13 active-site based on a total of 52 distance restraints. The binding motif of WAY-151693 in the MMP-13 complex is consistent with our previously reported MMP-1:CGS-27023A NMR structure and is similar to the MMP-13: RS-130830 X-ray structure.
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Structural relatedness of distinct determinants recognized by monoclonal antibody TP25.99 on beta 2-microglobulin-associated and beta 2-microglobulin-free HLA class I heavy chains. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 165:3275-83. [PMID: 10975844 DOI: 10.4049/jimmunol.165.6.3275] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The association of HLA class I heavy chains with beta2-microglobulin (beta2m) changes their antigenic profile. As a result, Abs react with either beta2m-free or beta2m-associated HLA class I heavy chains. An exception to this rule is the mAb TP25.99, which reacts with both beta2m-associated and beta2m-free HLA class I heavy chains. The reactivity with beta2m-associated HLA class I heavy chains is mediated by a conformational determinant expressed on all HLA-A, -B, and -C Ags. This determinant has been mapped to amino acid residues 194-198 in the alpha3 domain. The reactivity with beta2m-free HLA class I heavy chains is mediated by a linear determinant expressed on all HLA-B Ags except the HLA-B73 allospecificity and on <50% of HLA-A allospecificities. The latter determinant has been mapped to amino acid residues 239-242, 245, and 246 in the alpha3 domain. The conformational and the linear determinants share several structural features, but have no homology in their amino acid sequence. mAb TP25.99 represents the first example of a mAb recognizing two distinct and spatially distant determinants on a protein. The structural homology of a linear and a conformational determinant on an antigenic entity provides a molecular mechanism for the sharing of specificity by B and TCRs.
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Analysis by NMR spectroscopy of the structural homology between the linear and the cyclic peptide recognized by anti-human leukocyte antigen class I monoclonal antibody TP25.99*. J Biol Chem 2000; 275:24679-85. [PMID: 10825172 DOI: 10.1074/jbc.m003647200] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The anti-human leukocyte antigen (HLA) class I monoclonal antibody (mAb) TP25.99 has a unique specificity since it recognizes both a conformational and a linear determinant expressed on the beta(2)-mu-associated and beta(2)-mu-free HLA class I heavy chains, respectively. Previously, we reported the identification of a cyclic and a linear peptide that inhibits mAb TP25.99 binding to the beta(2)-mu-associated and beta(2)-mu-free HLA class I heavy chains (S. A. Desai, X. Wang, E. J. Noronha, Q. Zhou, V. Rebmann, H. Grosse-Wilde, F. J. Moy, R. Powers, and S. Ferrone, submitted for publication). The linear X(19) and cyclic LX-8 peptides contain sequence homologous to residues 239-242, 245, and 246 and to residues 194-198, respectively, of HLA class I heavy chain alpha(3) domain. Analysis by two-dimensional transfer nuclear Overhauser effect spectroscopy of the induced solution structures of the linear X(19) and cyclic LX-8 peptides in the presence of mAb TP25.99 showed that the two peptides adopt a similar structural motif despite the lack of sequence homology. The backbone fold is suggestive of a short helical segment followed by a tight turn, reminiscent of the determinant loop region (residues 194-198) on beta(2)-mu-associated HLA class I heavy chains. The structural similarity between the linear X(19) and cyclic LX-8 peptides and the lack of sequence homology suggests that mAb TP25.99 predominantly recognizes a structural motif instead of a consensus sequence.
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Abstract
ZipA, an essential component of cell division in Escherichia coli, interacts with the FtsZ protein at the midcell in one of the initial steps of septum formation. The high-resolution solution structure of the 144-residue C-terminal domain of E. coli ZipA (ZipA(185)(-)(328)) has been determined by multidimensional heteronuclear NMR. A total of 30 structures were calculated by means of hybrid distance geometry-simulated annealing using a total of 2758 experimental NMR restraints. The atomic root means square distribution about the mean coordinate positions for residues 6-142 for the 30 structures is 0.37 +/- 0.04 A for the backbone atoms, 0. 78 +/- 0.05 A for all atoms, and 0.45 +/- 0.04 A for all atoms excluding disordered side chains. The NMR solution structure of ZipA(185)(-)(328) is composed of three alpha-helices and a beta-sheet consisting of six antiparallel beta-strands where the alpha-helices and the beta-sheet form surfaces directly opposite each other. A C-terminal peptide from FtsZ has been shown to bind ZipA(185)(-)(328) in a hydrophobic channel formed by the beta-sheet providing insight into the ZipA-FtsZ interaction. An unexpected similarity between the ZipA(185)(-)(328) fold and the split beta-alpha-beta fold observed in many RNA binding proteins may further our understanding of the critical ZipA-FtsZ interaction.
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Mutational analysis and NMR studies of the death domain of the tumor necrosis factor receptor-1. J Mol Biol 2000; 300:1323-33. [PMID: 10903872 DOI: 10.1006/jmbi.2000.3899] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Tumor necrosis factor receptor-1 (TNFR-1) death domain (DD) is the intracellular functional domain responsible for the receptor signaling activities. To understand the transduction mechanism of TNFR-1 signaling we performed structural and functional analysis of the TNFR-DD. The secondary structure of the TNFR-DD shows that it consists of six anti-parallel alpha-helices. The determination of the topological fold and an extensive mutagenesis analysis revealed that there are two opposite faces that are involved in self-association and interaction with the TRADD death domain. Interestingly, the same critical residues in TNFR-DD are involved in both interactions. There is a good correlation between the binding activities of the mutant proteins and their cytotoxic activities. These results provide important insight into the molecular interactions mediating TNFR-DD self-association and subsequent recruitment of TRADD in the signaling activity of TNFR-1.
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MESH Headings
- Amino Acid Sequence
- Amino Acid Substitution/genetics
- Antigens, CD/chemistry
- Antigens, CD/genetics
- Antigens, CD/metabolism
- Binding Sites
- Dimerization
- Humans
- Models, Molecular
- Molecular Sequence Data
- Nuclear Magnetic Resonance, Biomolecular
- Osmolar Concentration
- Peptide Fragments/chemistry
- Peptide Fragments/genetics
- Peptide Fragments/metabolism
- Point Mutation/genetics
- Protein Binding
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Proteins/chemistry
- Proteins/metabolism
- Receptors, Tumor Necrosis Factor/chemistry
- Receptors, Tumor Necrosis Factor/genetics
- Receptors, Tumor Necrosis Factor/metabolism
- Receptors, Tumor Necrosis Factor, Type I
- Recombinant Proteins/chemistry
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Sequence Alignment
- Signal Transduction
- Structure-Activity Relationship
- TNF Receptor-Associated Factor 1
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Letter to the editor: 1H, 15N, 13C, and 13CO assignments and secondary structure determination of collagenase-3 (MMP-13) complexed with a hydroxamic acid inhibitor. JOURNAL OF BIOMOLECULAR NMR 2000; 17:269-270. [PMID: 10959634 DOI: 10.1023/a:1008305025043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Letter to the editor: 1H, 15N, 13C, and 13CO assignments and secondary structure determination of ZipA. JOURNAL OF BIOMOLECULAR NMR 2000; 17:275-276. [PMID: 10959637 DOI: 10.1023/a:1008331924928] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Abstract
Heterotrimeric guanine nucleotide-binding proteins (G-proteins) are transducers in many cellular transmembrane signaling systems where regulators of G-protein signaling (RGS) act as attenuators of the G-protein signal cascade by binding to the Galpha subunit of G-proteins (G(i)(alpha)(1)) and increasing the rate of GTP hydrolysis. The high-resolution solution structure of free RGS4 has been determined using two-dimensional and three-dimensional heteronuclear NMR spectroscopy. A total of 30 structures were calculated by means of hybrid distance geometry-simulated annealing using a total of 2871 experimental NMR restraints. The atomic rms distribution about the mean coordinate positions for residues 5-134 for the 30 structures is 0.47 +/- 0.05 A for the backbone atoms, 0. 86 +/- 0.05 A for all atoms, and 0.56 +/- 0.04 A for all atoms excluding disordered side chains. The NMR solution structure of free RGS4 suggests a significant conformational change upon binding G(i)(alpha)(1) as evident by the backbone atomic rms difference of 1. 94 A between the free and bound forms of RGS4. The underlying cause of this structural change is a perturbation in the secondary structure elements in the vicinity of the G(i)(alpha)(1) binding site. A kink in the helix between residues K116-Y119 is more pronounced in the RGS4-G(i)(alpha)(1) X-ray structure relative to the free RGS4 NMR structure, resulting in a reorganization of the packing of the N-terminal and C-terminal helices. The presence of the helical disruption in the RGS4-G(i)(alpha)(1) X-ray structure allows for the formation of a hydrogen-bonding network within the binding pocket for G(i)(alpha)(1) on RGS4, where RGS4 residues D117, S118, and R121 interact with residue T182 from G(i)(alpha)(1). The binding pocket for G(i)(alpha)(1) on RGS4 is larger and more accessible in the free RGS4 NMR structure and does not present the preformed binding site observed in the RGS4-G(i)(alpha)(1) X-ray structure. This observation implies that the successful complex formation between RGS4 and G(i)(alpha)(1) is dependent on both the formation of the bound RGS4 conformation and the proper orientation of T182 from G(i)(alpha)(1). The observed changes for the free RGS4 NMR structure suggest a mechanism for its selectivity for the Galpha-GTP-Mg(2+) complex and a means to facilitate the GTPase cycle.
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Computer voice recognition. Am J Orthod Dentofacial Orthop 2000; 117:504-6. [PMID: 10756281 DOI: 10.1016/s0889-5406(00)70007-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Densitometric analysis of Galphao protein subunit levels from postmortem Alzheimer disease hippocampal and prefrontal cortical membranes. Alzheimer Dis Assoc Disord 2000; 14:53-7. [PMID: 10718205 DOI: 10.1097/00002093-200001000-00007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
An immunoblotting method using prefrontal cortical and hippocampal membranes from control and Alzheimer disease postmortem brains was employed to detect three subtypes of Galphao protein. In the membranes from control subjects, the density of Galphao1 in hippocampus and cortex was the highest, whereas the density of Galphao2 was the lowest and that of Galphao3 was intermediate. In the Alzheimer disease membranes from hippocampus, the density of total Galphao and all three subtype forms was not changed significantly when compared with control values. There were statistically significant alterations in Galphao in cortical membranes from Alzheimer disease when compared with controls. The density of Galphao1 was decreased by approximately 85%, density of Galphao3 was decreased by approximately 95%, and total Galphao density was decreased by approximately 84% of control value. However, Galphao2 density was decreased by approximately 44% but was found not to be statistically different from controls.
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1H, 15N, 13C, and 13CO assignments and secondary structure determination of RGS4. JOURNAL OF BIOMOLECULAR NMR 1999; 15:339-340. [PMID: 10685342 DOI: 10.1023/a:1008343609739] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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35
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HYPER: a hierarchical algorithm for automatic determination of protein dihedral-angle constraints and stereospecific C beta H2 resonance assignments from NMR data. JOURNAL OF BIOMOLECULAR NMR 1999; 15:251-264. [PMID: 10677828 DOI: 10.1023/a:1008331216581] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A new computer program, HYPER, has been developed for automated analysis of protein dihedral angle values and C beta H2 stereospecific assignments from NMR data. HYPER uses a hierarchical grid-search algorithm to determine allowed values of phi, psi, and chi 1 dihedral angles and C beta H2 stereospecific assignments based on a set of NMR-derived distance and/or scalar-coupling constraints. Dihedral-angle constraints are valuable for restricting conformational space and improving convergence in three-dimensional structure calculations. HYPER computes the set of phi, psi, and chi 1 dihedral angles and C beta H2 stereospecific assignments that are consistent with up to nine intraresidue and sequential distance bounds, two pairs of relative distance bounds, thirteen homo- and heteronuclear scalar coupling bounds, and two pairs of relative scalar coupling constant bounds. The program is designed to be very flexible, and provides for simple user modification of Karplus equations and standard polypeptide geometries, allowing it to accommodate recent and future improved calibrations of Karplus curves. The C code has been optimized to execute rapidly (0.3-1.5 CPU-sec residue-1 using a 5 degrees grid) on Silicon Graphics R8000, R10000 and Intel Pentium CPUs, making it useful for interactive evaluation of inconsistent experimental constraints. The HYPER program has been tested for internal consistency and reliability using both simulated and real protein NMR data sets.
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NMR solution structure of the catalytic fragment of human fibroblast collagenase complexed with a sulfonamide derivative of a hydroxamic acid compound. Biochemistry 1999; 38:7085-96. [PMID: 10353819 DOI: 10.1021/bi982576v] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The solution structure of the catalytic fragment of human fibroblast collagenase (MMP-1) complexed with a sulfonamide derivative of a hydroxamic acid compound (CGS-27023A) has been determined using two-dimensional and three-dimensional heteronuclear NMR spectroscopy. The solution structure of the complex was calculated by means of hybrid distance geometry-simulated annealing using a combination of experimental NMR restraints obtained from the previous refinement of the inhibitor-free MMP-1 (1) and recent restraints for the MMP-1:CGS-27023A complex. The hydroxamic acid moiety of CGS-27023A was found to chelate to the "right" of the catalytic zinc where the p-methoxyphenyl sits in the S1' active-site pocket, the isopropyl group is in contact with H83 and N80, and the pyridine ring is solvent exposed. The sulfonyl oxygens are in hydrogen-bonding distance to the backbone NHs of L81 and A82. This is similar to the conformation determined by NMR of the inhibitor bound to stromelysin (2, 3). A total of 48 distance restraints were observed between MMP-1 and CGS-27023A from 3D 13C-edited/12C-filtered NOESY and 3D 15N-edited NOESY experiments. An additional 18 intramolecular restraints were observed for CGS-27023A from a 2D 12C-filtered NOESY experiment. A minimal set of NMR experiments in combination with the free MMP-1 assignments were used to assign the MMP-1 (1)H, 13C, and 15N resonances in the MMP-1:CGS-27023A complex. The assignments of CGS-27023A in the complex were obtained from 2D 12C-filtered NOESY and 2D 12C-filtered TOCSY experiments.
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37
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Opioid withdrawal in neonates after continuous infusions of morphine or fentanyl during extracorporeal membrane oxygenation. Am J Crit Care 1998. [DOI: 10.4037/ajcc1998.7.5.364] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
BACKGROUND: Complications of opioid analgesia include tolerance and withdrawal. OBJECTIVES: To determine the effects of morphine and fentanyl on the prevalence of withdrawal after extracorporeal membrane oxygenation. METHODS: Two groups of neonates were compared during and after extracorporeal membrane oxygenation: a prospective group receiving a continuous infusion of morphine for analgesia and sedation and a retrospective group who had received a continuous infusion of fentanyl. RESULTS: Neonates receiving morphine required significantly less supplemental analgesia (P < .001) than did neonates who had received fentanyl and had a significantly lower prevalence of withdrawal after the therapy (P = .01). Neonates receiving morphine were discharged from the hospital a mean of 9.6 days sooner (P = .01) than neonates who had received fentanyl. CONCLUSIONS: Morphine may offer marked advantages over fentanyl for providing continuous analgesia and sedation in neonates.
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Concomitant rash and blood dyscrasias in geriatric psychiatry patients treated with carbamazepine. Ann Pharmacother 1998; 32:884-7. [PMID: 9762374 DOI: 10.1345/aph.17445] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND Rashes and blood dyscrasias are disconcerting adverse effects associated with carbamazepine therapy. Rashes are quite common, as are mild blood dyscrasias, such as mild leukopenias. Fortunately, severe rashes and blood dyscrasias are rare. There are few reports on the relationship between carbamazepine-induced rashes and blood dyscrasias, including a prospective study in which rash appeared concomitantly with leukopenia and/or thrombocytopenia in 10 patients, two case reports in which simultaneous rash and agranulocytosis occurred, and two case reports in which rashes served as harbingers of fatal aplastic anemia. CASE REPORTS We report two cases of concomitant rashes and blood dyscrasias in geriatric psychiatry patients receiving carbamazepine therapy for bipolar disorder. One patient was found to have a severe leukopenia within several days after rash onset. The other patient was discovered to have a severe leukopenia and thrombocytopenia within about a month after rash onset. DISCUSSION Current hematologic monitoring guidelines for carbamazepine rely heavily on the recognition of signs and symptoms of blood dyscrasias by clinicians and patients. We believe that our cases support the suggestion that patients who develop rashes receive more vigilant monitoring of the complete blood count, should carbamazepine therapy by continued. Given the currently available case reports and the fact that the incidence of drug-induced blood dyscrasias increases with advanced age, this recommendation may be particularly relevant for geriatric patients. CONCLUSIONS Further study is required to establish whether carbamazepine-induced concomitant rashes and blood dyscrasias are valid associations insofar as monitoring is concerned.
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Opioid withdrawal in neonates after continuous infusions of morphine or fentanyl during extracorporeal membrane oxygenation. Am J Crit Care 1998; 7:364-9. [PMID: 9740886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND Complications of opioid analgesia include tolerance and withdrawal. OBJECTIVES To determine the effects of morphine and fentanyl on the prevalence of withdrawal after extracorporeal membrane oxygenation. METHODS Two groups of neonates were compared during and after extracorporeal membrane oxygenation: a prospective group receiving a continuous infusion of morphine for analgesia and sedation and a retrospective group who had received a continuous infusion of fentanyl. RESULTS Neonates receiving morphine required significantly less supplemental analgesia (P < .001) than did neonates who had received fentanyl and had a significantly lower prevalence of withdrawal after the therapy (P = .01). Neonates receiving morphine were discharged from the hospital a mean of 9.6 days sooner (P = .01) than neonates who had received fentanyl. CONCLUSIONS Morphine may offer marked advantages over fentanyl for providing continuous analgesia and sedation in neonates.
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Abstract
Oncostatin M (OM) is a member of the cytokine family which regulates the proliferation and differentiation of a variety of cell types and includes interleukin-6 (IL-6), leukemia inhibitory factor (LIF), and granulocyte-colony stimulating factor (G-CSF). This family of proteins adopts a four-helix bundle fold with up-up-down-down topology and contains intramolecular disulfide bonds. Since an X-ray or NMR structure for OM is not currently available, a homology model for OM was determined from the X-ray structures of human growth hormone (hGH), LIF, and G-CSF where the alignment was based on secondary structure instead of sequence. The OM secondary structure was determined from NMR structural data, and the secondary structures for hGH, LIF, and G-CSF were obtained from the reported X-ray structures. The resulting homology model was refined using sequential NOE distance 13C restraints, chemical shift information, and a conformational database.
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Abstract
The primary purpose of this investigation was to determine the oral health status of individual's undergoing renal dialysis in southeastern Virginia. A sample was identified for this cross-sectional study via a local health maintenance organization. Three subgroups of the population were studied: 1) those who have been on renal dialysis for less than a year; 2) those on renal dialysis for 1 to 3 years; and 3) those on renal dialysis for longer than 3 years. Three dental indices the Periodontal Disease Index; the Decayed, Missing. Filled index; and the Simplified Oral Hygiene Index--were used to identify periodontal disease, dental caries activity, and oral hygiene status. Data were compiled and analyzed by using the parametric test, 1-way analysis of variance. Results suggested that 100% (n = 45) of the individuals undergoing renal dialysis presented with some form of periodontal disease (X = 3.15, SD = 1.41). The majority (64%) of the sample displayed either severe gingivitis (28%) or early periodontitis (36%). Sixty-four percent of the sample displayed a high DMF index (X = 11.77, SD = 7.55), while 98% of the sample accumulated calculus. Oral debris was present in 100% of the sample, resulting in a high Simplified Oral Hygiene Index score (X = 3.24, SD = 1.26), suggesting an increased need for oral care instruction. Findings led to the conclusion that the renal dialysis population in southeastern Virginia, regardless of length of time on dialysis, is in need of comprehensive professional oral care and self-care instruction. Oral disease was present and is a source of active infection in these medically compromised individuals and, as such, has dire implication for morbidity and mortality.
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High-resolution solution structure of the inhibitor-free catalytic fragment of human fibroblast collagenase determined by multidimensional NMR. Biochemistry 1998; 37:1495-504. [PMID: 9484219 DOI: 10.1021/bi972181w] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The high-resolution solution structure of the inhibitor-free catalytic fragment of human fibroblast collagenase (MMP-1), a protein of 18.7 kDa, which is a member of the matrix metalloproteinase family, has been determined using three-dimensional heteronuclear NMR spectroscopy. A total of 30 structures were calculated by means of hybrid distance geometry-simulated annealing using a total of 3333 experimental NMR restraints, consisting of 2409 approximate interproton distance restraints, 84 distance restraints for 42 backbone hydrogen bonds, 426 torsion angle restraints, 125 3JNH alpha restraints, 153 C alpha restraints, and 136 C beta restraints. The atomic rms distribution about the mean coordinate positions for the 30 structures for residues 7-137 and 145-163 is 0.42 +/- 0.04 A for the backbone atoms, 0.80 +/- 0.04 A for all atoms, and 0.50 +/- 0.03 A for all atoms excluding disordered side chains. The overall structure of MMP-1 is composed of a beta-sheet consisting of five beta-strands in a mixed parallel and anti-parallel arrangement and three alpha-helices. A best-fit superposition of the NMR structure of inhibitor-free MMP-1 with the 1.56 A resolution X-ray structure by Spurlino et al. [Spurlino, J. C., Smallwood, A. M., Carlton, D. D., Banks, T. M., Vavra, K. J., Johnson, J. S., Cook, E. R., Falvo, J., and Wahl, R. C., et al. (1994) Proteins: Struct., Funct., Genet. 19, 98-109] complexed with a hydroxamate inhibitor yields a backbone atomic rms difference of 1.22 A. The majority of differences between the NMR and X-ray structure occur in the vicinity of the active site for MMP-1. This includes an increase in mobility for residues 138-144 and a displacement for the Ca(2+)-loop (residues 74-80). Distinct differences were observed for side-chain torsion angles, in particular, the chi 1 for N80 is -60 degrees in the NMR structure compared to 180 degrees in the X-ray. This results in the side chain of N80 occupying and partially blocking access to the active site of MMP-1.
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Assignments, secondary structure and dynamics of the inhibitor-free catalytic fragment of human fibroblast collagenase. JOURNAL OF BIOMOLECULAR NMR 1997; 10:9-19. [PMID: 9335112 DOI: 10.1023/a:1018362914316] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Fibroblast collagenase (MMP-1), a 169-residue protein with a molecular mass of 18.7 kDa, is a matrix metalloproteinase which has been associated with pathologies such as arthritis and cancer. The assignments of the 1H, 15N, 13CO and 13C resonances, determination of the secondary structure and analysis of 15N relaxation data of the inhibitor-free catalytic fragment of recombinant human fibroblast collagenase (MMP-1) are presented. It is shown that MMP-1 is composed of a beta-sheet consisting of five beta-strands in a mixed parallel and antiparallel arrangement (residues 13-19, 48-53, 59-65, 82-85 and 94-99) and three alpha-helices (residues 27-43, 112-124 and 150-160). This is nearly identical to the secondary structure determined from the refined X-ray crystal structures of inhibited MMP-1. The major difference observed between the NMR solution structure of inhibitor-free MMP-1 and the X-ray structures of inhibited MMP-1 is the dynamics of the active site. The 2D 15N-1H HSQC spectra, the lack of information in the 15N-edited NOESY spectra, and the generalized order parameters (S2) determined from 15N T1, T2 and NOE data suggest a slow conformational exchange for residues comprising the active site (helix B, zinc ligated histidines and the nearby loop region) and a high mobility for residues Pro138-Gly144 in the vicinity of the active site for inhibitor-free collagenase. In contrast to the X-ray structures, only the slow conformational exchange is lost in the presence of an inhibitor.
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Abstract
An expert system for determining resonance assignments from NMR spectra of proteins is described. Given the amino acid sequence, a two-dimensional 15N-1H heteronuclear correlation spectrum and seven to eight three-dimensional triple-resonance NMR spectra for seven proteins, AUTOASSIGN obtained an average of 98% of sequence-specific spin-system assignments with an error rate of less than 0.5%. Execution times on a Sparc 10 workstation varied from 16 seconds for smaller proteins with simple spectra to one to nine minutes for medium size proteins exhibiting numerous extra spin systems attributed to conformational isomerization. AUTOASSIGN combines symbolic constraint satisfaction methods with a domain-specific knowledge base to exploit the logical structure of the sequential assignment problem, the specific features of the various NMR experiments, and the expected chemical shift frequencies of different amino acids. The current implementation specializes in the analysis of data derived from the most sensitive of the currently available triple-resonance experiments. Potential extensions of the system for analysis of additional types of protein NMR data are also discussed.
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Properly oriented heparin-decasaccharide-induced dimers are the biologically active form of basic fibroblast growth factor. Biochemistry 1997; 36:4782-91. [PMID: 9125499 DOI: 10.1021/bi9625455] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Interaction of basic fibroblast growth factor (FGF-2) with heparin or heparan sulfate proteoglycans (HSPGs) is required for receptor activation and initiation of biological responses. To gain insight into the mechanism of activation of the FGF receptor by FGF-2 and heparin, we have used NMR, dynamic light scattering, and HSPG-deficient cells and cell-free systems. The first 28 N-terminal residues in FGF-2 were found to be highly mobile and flexible, consistent with the disorder found in both the NMR and X-ray structures. The structure of an FGF-2-heparin-decasaccharide complex that binds to and activates the FGF receptor was compared to a heparin-tetrasaccharide-induced complex that does not promote an interaction with the receptor. The major change observed upon the addition of the tetrasaccharide to FGF-2 was an increase in the correlation time consistent with the formation of an FGF-2 dimer. The NMR line widths of FGF-2 in the presence of the decasaccharide are severely broadened relative to the tetrasaccharide, consistent with dynamic light scattering results which indicate FGF-2 is a tetramer. The interaction of these heparin species with FGF-2 does not induce a significant conformational change in the overall structure of FGF-2, but small chemical shift changes are observed in both heparin and receptor binding sites. A trans-oriented symmetric dimer of FGF-2 is formed in the presence of the tetrasaccharide whereas two cis-oriented dimers in a symmetric tetramer are formed in the presence of the decasaccharide. This suggests that the cis-oriented FGF-2 dimer is the minimal biologically active structural unit of FGF-2. These data allow us to propose a novel mechanism to explain the functional interaction of FGF-2 with heparin and its transmembrane receptor.
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Abstract
As meiosis is initiated and the oogonium is transformed into a primary oocyte, the female germ cell becomes intimately invested by a single squamous layer of sex cord epithelium. As the follicle cell population expands during the initial stages of the ovarian cycle, oocyte and follicle cells become increasingly connected to one another by one of the most extensive populations of gap junctions documented in any epithelium (reviewed in Larsen & Wert, 1988).
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High-resolution solution structure of basic fibroblast growth factor determined by multidimensional heteronuclear magnetic resonance spectroscopy. Biochemistry 1996; 35:13552-61. [PMID: 8885834 DOI: 10.1021/bi961260p] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The high-resolution solution structure of recombinant human basic fibroblast growth factor (FGF-2), a protein of 17.2 kDa that exhibits a variety of functions related to cell growth and differentiation, has been determined using three-dimensional heteronuclear NMR spectroscopy. A total of 30 structures were calculated by means of hybrid distance geometry--simulated annealing using a total of 2865 experimental NMR restraints, consisting of 2486 approximate inteproton distance restraints, 50 distance restraints for 25 backbone hydrogen bonds, and 329 torsion angle restraints. The atomic rms distribution about the mean coordinate positions for the 30 structures for residues 29-152 is 0.43 +/- 0.03 A for the backbone atoms, 0.83 +/- 0.05 A for all atoms, and 0.51 +/- 0.04 A for all atoms excluding disordered side chains. The overall structure of FGF-2 consists of 11 extended antiparallel beta-strands arranged in three groups of three or four strands connected by tight turns and loop regions creating a pseudo-3-fold symmetry. Two strands from each group come together to form a beta-sheet barrel of six antiparallel beta-strands. A helix-like structure was observed for residues 131-136, which is part of the heparin binding site (residues 128-138). The discovery of the helix-like region in the primary heparin binding site instead of the beta-strand conformation described in the X-ray structures may have important implications in understanding the nature of heparin--FGF-2 interactions. A total of seven tightly bound water molecules were found in the FGF-2 structure, two of which are located in the heparin binding site. The first 28 N-terminal residues appear to be disordered, which is consistent with previous X-ray structures. A best fit superposition of the NMR structure of FGF-2 with the 1.9 A resolution X-ray structure by Zhu et al. (1991) yields a backbone atomic rms difference of 0.94 A, indicative of a close similarity between the NMR and X-ray structures.
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Resonance assignments for Oncostatin M, a 24-kDa alpha-helical protein. JOURNAL OF BIOMOLECULAR NMR 1996; 7:273-282. [PMID: 8765735 DOI: 10.1007/bf00200429] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Oncostatin M (OM) is a cytokine that shares a structural and functional relationship with interleukin-6, leukemia inhibitory factor, and granulocyte-colony stimulating factor, which regulate the proliferation and differentiation of a variety of cell types. A mutant version of human OM in which two N-linked glycosylation sites and an unpaired cysteine have been mutated to alanine (N76A/C81A/N193A) has been expressed and shown to be active. The triple mutant has been doubly isotope-labeled with 13C and 15N in order to utilize heteronuclear multidimensional NMR techniques for structure determination. Approximately 90% of the backbone resonances were assigned from a combination of triple-resonance data (HNCA, HNCO, CBCACONH, HBHACONH, HNHA and HCACO), intraresidue and sequential NOEs (3D 15N-NOESY-HMQC and 13C-HSQC-NOESY) and side-chain information obtained from the CCONH and HCCONH experiments. Preliminary analysis of the NOE pattern in the 15N-NOESY-HMQC spectrum and the 13C alpha secondary chemical shifts predicts a secondary structure for OM consisting of four alpha-helices with three intervening helical regions, consistent with the four-helix-bundle motif found for this cytokine family. As a 203-residue protein with a molecular weight of 24 kDa, Oncostatin M is the largest alpha-helical protein yet assigned.
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Abstract
Much of the literature shows various regional structural brain abnormalities in schizophrenia, but the complexity and variability of brain makes it difficult to determine how these regions are related. Statistical methods which estimate factors underlying patterns of covariance have not been widely used, but could be useful for analyzing such complex data. We applied exploratory and confirmatory factor analysis procedures to specific cortical and subcortical regional brain volume measures from MRI data in 60 normal and 44 schizophrenic subjects. Basal ganglia, heteromodal cortical gray, and medial temporal lobe factors were present in both the normal and the schizophrenia groups. The factor structure observed in the normal group showed a high degree of bilateral symmetry which is present but disrupted in the schizophrenia group. In the bilateral data, the disruption is most pronounced with medial and lateral temporal lobe structures including entorhinal cortex and anterior and posterior superior temporal gyri. There was a significant correlation between the basal ganglia factor and the heteromodal cortical gray factor in the normal group that was not present in the schizophrenia group. In the unilateral data, left posterior superior temporal gyrus did not load onto any factor in the schizophrenia group. Confirmatory factor analyses showed significant differences between the two groups in factor structure. A number of specific brain regions are affected in schizophrenia, and structural relationships between groups of regions also are abnormal. The results suggest that heteromodal dorsolateral prefrontal and superior temporal cortical gray regions are structurally related, whereas inferior parietal cortical gray is less so. These results should be viewed as preliminary as the ratio of parameters to subjects was relatively low, and replication is needed. However, the results demonstrate the potential utility of latent structure methods such as factor analysis in study of complex relationships in neuropsychiatric data.
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Abstract
Heterotrimeric G-proteins are critical components in many receptor-coupled signal transduction systems, and altered levels and functions of G-proteins have been implicated in several neurological disorders, including Alzheimer's disease. Investigations in postmortem human brain provide a direct approach to study G-protein involvement in neurological disorders. Therefore, the effects of postmortem interval, aging, and Alzheimer's disease on G-protein levels were determined in postmortem human brain and an assay to measure activation of G-proteins was developed. Within the postmortem interval range of 5 to 21 h, the levels of G alpha i1, G alpha i2, G alpha s, and G beta were stable, whereas G alpha q and G alpha o decreased slightly, in human prefrontal cortex. In subjects aged 19 to 100 y, decreased levels of G alpha q and G alpha o were significantly correlated with increased age, but levels of the other G-protein subunits did not vary. In Alzheimer's disease prefrontal cortex, superior temporal gyrus, and occipital cortex, all G-protein subunit levels were equivalent to those in matched controls except for a slight deficit in G alpha i1. An ELISA assay using selective antibodies was used to measure [35S]GTP gamma S binding to G alpha o and G alpha i1. Binding was proportional to the concentration of GTP-gamma S and was concentration-dependently stimulated by mastoparan equivalently in control and Alzheimer's disease prefrontal cortical membranes.
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