scholarly journals Biochemical characterization ofMLH3missense mutations does not reveal an apparent role of MLH3 in Lynch syndrome

2009 ◽  
Vol 48 (4) ◽  
pp. 340-350 ◽  
Author(s):  
Jianghua Ou ◽  
Merete Rasmussen ◽  
Helga Westers ◽  
Sofie D. Andersen ◽  
Paul O. Jager ◽  
...  
Keyword(s):  
Lynch Syndrome ◽  
Biochemical Characterization

scholarly journals Role of the Ser-287-Asn Replacement in the Hydrolysis Spectrum Extension of AmpC β-Lactamases in Escherichia coli

2008 ◽  
Vol 53 (1) ◽  
pp. 323-326 ◽  
Author(s):  
Hedi Mammeri ◽  
Moreno Galleni ◽  
Patrice Nordmann
Keyword(s):  
Escherichia Coli ◽  
Biochemical Characterization ◽  
Catalytic Efficiency ◽  
Phylogenetic Groups ◽  
Extended Spectrum ◽  
Group A

ABSTRACT Two AmpC variants harboring the S287N substitution were obtained by mutagenesis from cephalosporinases representative of the phylogenetic groups A and B2 of Escherichia coli. Their biochemical characterization revealed that the S287N replacement led to an important increase in the catalytic efficiency toward extended-spectrum cephalosporins in the AmpC β-lactamase of group A only.

Role of Prophylactic Colectomy in Lynch Syndrome

2003 ◽  
Vol 3 (2) ◽  
pp. 99-101 ◽  
Author(s):  
Henry T. Lynch ◽  
Jane F. Lynch ◽  
Robert Fitzgibbons
Keyword(s):  
Lynch Syndrome ◽  
Prophylactic Colectomy

scholarly journals Structural and biochemical characterization of the environmental MBLs MYO-1, ECV-1 and SHD-1

2020 ◽  
Vol 75 (9) ◽  
pp. 2554-2563 ◽  
Author(s):  
Christopher Fröhlich ◽  
Vidar Sørum ◽  
Sandra Huber ◽  
Ørjan Samuelsen ◽  
Fanny Berglund ◽  
...  
Keyword(s):  
Biochemical Characterization ◽  
Homology Modelling ◽  
Catalytic Efficiency ◽  
Hydrolytic Activity ◽  
Human Pathogens ◽  
E Coli ◽  
X Ray Crystallography ◽  
Environmental Reservoir

Abstract Background MBLs form a large and heterogeneous group of bacterial enzymes conferring resistance to β-lactam antibiotics, including carbapenems. A large environmental reservoir of MBLs has been identified, which can act as a source for transfer into human pathogens. Therefore, structural investigation of environmental and clinically rare MBLs can give new insights into structure–activity relationships to explore the role of catalytic and second shell residues, which are under selective pressure. Objectives To investigate the structure and activity of the environmental subclass B1 MBLs MYO-1, SHD-1 and ECV-1. Methods The respective genes of these MBLs were cloned into vectors and expressed in Escherichia coli. Purified enzymes were characterized with respect to their catalytic efficiency (kcat/Km). The enzymatic activities and MICs were determined for a panel of different β-lactams, including penicillins, cephalosporins and carbapenems. Thermostability was measured and structures were solved using X-ray crystallography (MYO-1 and ECV-1) or generated by homology modelling (SHD-1). Results Expression of the environmental MBLs in E. coli resulted in the characteristic MBL profile, not affecting aztreonam susceptibility and decreasing susceptibility to carbapenems, cephalosporins and penicillins. The purified enzymes showed variable catalytic activity in the order of <5% to ∼70% compared with the clinically widespread NDM-1. The thermostability of ECV-1 and SHD-1 was up to 8°C higher than that of MYO-1 and NDM-1. Using solved structures and molecular modelling, we identified differences in their second shell composition, possibly responsible for their relatively low hydrolytic activity. Conclusions These results show the importance of environmental species acting as reservoirs for MBL-encoding genes.

scholarly journals Functional genetic encoding of sulfotyrosine in mammalian cells

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Xinyuan He ◽  
Yan Chen ◽  
Daisy Guiza Beltran ◽  
Maia Kelly ◽  
Bin Ma ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Biochemical Characterization ◽  
Trna Synthetase ◽  
Functional Verification ◽  
Cellular Processes ◽  
Genetic Encoding ◽  
Efficient Expression

Abstract Protein tyrosine O-sulfation (PTS) plays a crucial role in extracellular biomolecular interactions that dictate various cellular processes. It also involves in the development of many human diseases. Regardless of recent progress, our current understanding of PTS is still in its infancy. To promote and facilitate relevant studies, a generally applicable method is needed to enable efficient expression of sulfoproteins with defined sulfation sites in live mammalian cells. Here we report the engineering, in vitro biochemical characterization, structural study, and in vivo functional verification of a tyrosyl-tRNA synthetase mutant for the genetic encoding of sulfotyrosine in mammalian cells. We further apply this chemical biology tool to cell-based studies on the role of a sulfation site in the activation of chemokine receptor CXCR4 by its ligand. Our work will not only facilitate cellular studies of PTS, but also paves the way for economical production of sulfated proteins as therapeutic agents in mammalian systems.

Update on the role of chromoendoscopy in colonoscopic surveillance of patients with Lynch syndrome

2018 ◽  
Vol 30 (10) ◽  
pp. 1116-1124
Author(s):  
Alouisa J.P. van de Wetering ◽  
Roel M.M. Bogie ◽  
Assi C.O.G. Cabbolet ◽  
Bjorn Winkens ◽  
Ad A.M. Masclee ◽  
...  
Keyword(s):  
Lynch Syndrome ◽  
Colonoscopic Surveillance

scholarly journals Role of microsatellite instability-low as a diagnostic biomarker of Lynch syndrome in colorectal cancer

2014 ◽  
Vol 207 (10-12) ◽  
pp. 495-502 ◽  
Author(s):  
Eduardo Vilar ◽  
Maureen E. Mork ◽  
Amanda Cuddy ◽  
Ester Borras ◽  
Sarah A. Bannon ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Lynch Syndrome ◽  
Microsatellite Instability ◽  
Diagnostic Biomarker

scholarly journals Electron Transfer and Binding of thec-Type Cytochrome TorC to the TrimethylamineN-Oxide Reductase inEscherichia coli

2000 ◽  
Vol 276 (15) ◽  
pp. 11545-11551 ◽  
Author(s):  
Stéphanie Gon ◽  
Marie-Thérèse Giudici-Orticoni ◽  
Vincent Méjean ◽  
Chantal Iobbi-Nivol
Keyword(s):  
Electron Transfer ◽  
Biochemical Characterization ◽  
Reduced Form ◽  
Visible Absorption ◽  
Midpoint Potential ◽  
Redox Potentiometry ◽  
Family Based ◽  
Transfer Chain

Reduction of trimethylamineN-oxide (E′0(TMAO/TMA)= +130 mV) inEscherichia coliis carried out by the Tor system, an electron transfer chain encoded by thetorCADoperon and made up of the periplasmic terminal reductase TorA and the membrane-anchored pentahemicc-type cytochrome TorC. Although the role of TorA in the reduction of trimethylamineN-oxide (TMAO) has been clearly established, no direct evidence for TorC involvement has been presented. TorC belongs to the NirT/NapCc-type cytochrome family based on homologies of its N-terminal tetrahemic domain (TorCN) to the cytochromes of this family, but TorC contains a C-terminal extension (TorCC) with an additional heme-binding site. In this study, we show that both domains are required for the anaerobic bacterial growth with TMAO. The intact TorC protein and its two domains, TorCNand TorCC, were produced independently and purified for a biochemical characterization. The reduced form of TorC exhibited visible absorption maxima at 552, 523, and 417 nm. Mediated redox potentiometry of the heme centers of the purified components identified two negative midpoint potentials (−177 and −98 mV) localized in the tetrahemic TorCNand one positive midpoint potential (+120 mV) in the monohemic TorCC. In agreement with these values, thein vitroreconstitution of electron transfer between TorC, TorCN, or TorCCand TorA showed that only TorC and TorCCwere capable of electron transfer to TorA. Surprisingly, interaction studies revealed that only TorC and TorCNstrongly bind TorA. Therefore, TorCCdirectly transfers electrons to TorA, whereas TorCN, which probably receives electrons from the menaquinone pool, is involved in both the electron transfer to TorCCand the binding to TorA.

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