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https://www.readbyqxmd.com/read/28535274/development-of-carbapenem-resistance-in-pseudomonas-aeruginosa-is-associated-with-oprd-polymorphisms-particularly-the-amino-acid-substitution-at-codon-170
#1
Jwu-Ching Shu, An-Jing Kuo, Lin-Hui Su, Tsui-Ping Liu, Ming-Hsun Lee, I-Ning Su, Tsu-Lan Wu
Objectives: Pan-susceptible Pseudomonas aeruginosa (PSPA) clinical isolates carrying an OprD with loop 7 shortening (the group-1A allele) were found to rapidly develop carbapenem resistance under continuous selection pressure. We further studied whether OprD polymorphisms are associated with the potential to develop carbapenem resistance. Methods: OprD amino acid sequences of 126 PSPA clinical isolates were analysed to determine their STs using P. aeruginosa strain PAO1 as the control strain...
May 23, 2017: Journal of Antimicrobial Chemotherapy
https://www.readbyqxmd.com/read/28534738/optocontrol-of-glutamate-receptor-activity-by-single-side-chain-photoisomerization
#2
Viktoria Klippenstein, Christian Hoppmann, Shixin Ye, Lei Wang, Pierre Paoletti
Engineering light-sensitivity into proteins has wide ranging applications in molecular studies and neuroscience. Commonly used tethered photoswitchable ligands, however, require solvent-accessible protein labeling, face structural constrains, and are bulky. Here, we designed a set of optocontrollable NMDA receptors by directly incorporating single photoswitchable amino acids (PSAAs) providing genetic encodability, reversibility, and site tolerance. We identified several positions within the multi-domain receptor endowing robust photomodulation...
May 23, 2017: ELife
https://www.readbyqxmd.com/read/28534482/an-engineered-high-affinity-fbs1-carbohydrate-binding-protein-for-selective-capture-of-n-glycans-and-n-glycopeptides
#3
Minyong Chen, Xiaofeng Shi, Rebecca M Duke, Cristian I Ruse, Nan Dai, Christopher H Taron, James C Samuelson
A method for selective and comprehensive enrichment of N-linked glycopeptides was developed to facilitate detection of micro-heterogeneity of N-glycosylation. The method takes advantage of the inherent properties of Fbs1, which functions within the ubiquitin-mediated degradation system to recognize the common core pentasaccharide motif (Man3GlcNAc2) of N-linked glycoproteins. We show that Fbs1 is able to bind diverse types of N-linked glycomolecules; however, wild-type Fbs1 preferentially binds high-mannose-containing glycans...
May 23, 2017: Nature Communications
https://www.readbyqxmd.com/read/28533784/the-divergence-of-flowering-time-modulated-by-ft-tfl1-is-independent-to-their-interaction-and-binding-activities
#4
Zhen Wang, Ruiguang Yang, Upendra K Devisetty, Julin N Maloof, Yang Zuo, Jingjing Li, Yuxiao Shen, Jian Zhao, Manzhu Bao, Guogui Ning
FLOWERING LOCUS T (FT) and TERMINAL FLOWER1 (TFL1) proteins share highly conserved amino acid residues but they play opposite regulatory roles in promoting and repressing the flowering response, respectively. Previous substitution models and functional analysis have identified several key amino acid residues which are critical for the promotion of flowering. However, the precise relationship between naturally occurring FT/TFL1 homologs and the mechanism of their role in flowering is still unclear. In this study, FT/TFL1 homologs from eight Rosaceae species, namely, Spiraea cantoniensis, Pyracantha fortuneana, Photinia serrulata, Fragaria ananassa, Rosa hybrida, Prunus mume, Prunus persica and Prunus yedoensis, were isolated...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28533430/heme-thiolate-sulfenylation-of-human-cytochrome-p450-4a11-functions-as-a-redox-switch-for-catalytic-inhibition
#5
Matthew E Albertolle, Donghak Kim, Leslie D Nagy, Chul-Ho Yun, Ambra Pozzi, Uzen Savas, Eric F Johnson, F Peter Guengerich
Cytochrome P450 (P450, CYP) 4A11 is a human fatty acid ω-hydroxylase that catalyzes the oxidation of arachidonic acid to the eicosanoid 20- hydroxyeicosatetraenoic acid (20-HETE), which plays important roles in regulating blood pressure regulation. Variants of P450 4A11 have been associated with high blood pressure and resistance to anti-hypertensive drugs, and 20-HETE has both pro- and antihypertensive properties relating to increased vasoconstriction and natriuresis, respectively. These physiological activities are likely influenced by the redox environment, but the mechanisms are unclear...
May 22, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28533407/histone-binding-of-dpf2-mediates-its-repressive-role-in-myeloid-differentiation
#6
Ferdinand M Huber, Sarah M Greenblatt, Andrew M Davenport, Concepcion Martinez, Ye Xu, Ly P Vu, Stephen D Nimer, André Hoelz
Double plant homeodomain finger 2 (DPF2) is a highly evolutionarily conserved member of the d4 protein family that is ubiquitously expressed in human tissues and was recently shown to inhibit the myeloid differentiation of hematopoietic stem/progenitor and acute myelogenous leukemia cells. Here, we present the crystal structure of the tandem plant homeodomain finger domain of human DPF2 at 1.6-Å resolution. We show that DPF2 interacts with the acetylated tails of both histones 3 and 4 via bipartite binding pockets on the DPF2 surface...
May 22, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28533241/arr-cb-a-rifampin-resistance-determinant-found-active-or-cryptic-in-clostridium-bolteae
#7
Jean-Christophe Marvaud, Thierry Lambert
Clostridium bolteae, which belongs to the Clostridium clostridioforme complex is a member of the human gut microbiota. Recent analysis of seven genomes of C. bolteae revealed the presence of an arr-like gene. Among these strains only 90A7 was found to be resistant to rifampin in the absence of alteration in RpoB. Cloning of arr-cb from 90A7 in Escherichia coli combined with directed mutagenesis demonstrated that Arr-cb is functional but that a Q127→R variant present in 90A9 and 90B3 was inactive. qRT-PCR analysis indicated that arr-cb was silent in the four remaining strains due to a defective transcription...
May 22, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28533123/molecular-characterization-of-caulobacter-crescentus-mutator-strains
#8
Marinalva Martins-Pinheiro, Alice R Oliveira, Alexy O Valencia, Frank S Fernandez-Silva, Larissa G Silva, Carina O Lopes-Kulishev, Valeria C S Italiani, Marilis V Marques, Carlos F Menck, Rodrigo S Galhardo
Mutator strains were identified by screening random Tn5 insertion clones of Caulobacter crescentus. We identified clones with robust increases in mutation rates with Tn5 insertions in the mutY, mutS, mutL and uvrD genes, known to act in mutation-preventing pathways in Escherichia coli. Analysis of mutations in the rpoB gene revealed that in both the parental strain and mismatch repair-deficient mutants, A:T→G:C transitions predominate by a large margin over C:G→T:A. We have also investigated the role of the error-prone polymerase encoded by imuC (dnaE2) in spontaneous mutagenesis, and found that a imuC mutant strain shows mutation rates and sequences comparable to the parental strain...
May 19, 2017: Gene
https://www.readbyqxmd.com/read/28531887/expression-and-characterization-of-membrane-type-4-matrix-metalloproteinase-mt4-mmp-and-its-different-forms-in-melanoma
#9
Bettina Hieronimus, Julian Pfohl, Christian Busch, Lutz Graeve
BACKGROUND/AIMS: Membrane-type matrix metalloproteinases (MT-MMPs) are expressed on the cell surface and hydrolyze extracellular matrix components and signaling molecules by which they influence cancer cell migration and metastasis. Two of the six known MT-MMPs are anchored to the plasma membrane via a GPI anchor, one of which is MT4-MMP. Only little is known about MT4-MMP expression, synthesis, regulation and degradation. METHODS: We analyzed several human cancer cell lines as well as tissue homogenates using Western blotting and quantitative PCR for the expression of MT4-MMP...
May 25, 2017: Cellular Physiology and Biochemistry
https://www.readbyqxmd.com/read/28531234/directed-evolution-to-improve-the-catalytic-efficiency-of-urate-oxidase-from-bacillus-subtilis
#10
Wenjie Li, Shouteng Xu, Biao Zhang, Yelin Zhu, Yan Hua, Xin Kong, Lianhong Sun, Jiong Hong
Urate oxidase is a key enzyme in purine metabolism and catalyzes the oxidation of uric acid to allantoin. It is used to treat hyperuricemia and gout, and also in a diagnostic kit. In this study, error-prone polymerase chain reaction and staggered extension process was used to generate a mutant urate oxidase with improved enzyme activity from Bacillus subtilis. After several rounds of mutagenesis and screening, two mutants 6E9 and 8E279 were obtained which exhibited 2.99 and 3.43 times higher catalytic efficiency, respectively...
2017: PloS One
https://www.readbyqxmd.com/read/28531220/highly-conserved-type-1-pili-promote-enterotoxigenic-e-coli-pathogen-host-interactions
#11
Alaullah Sheikh, Rasheduzzaman Rashu, Yasmin Ara Begum, F Matthew Kuhlman, Matthew A Ciorba, Scott J Hultgren, Firdausi Qadri, James M Fleckenstein
Enterotoxigenic Escherichia coli (ETEC), defined by their elaboration of heat-labile (LT) and/or heat-stable (ST) enterotoxins, are a common cause of diarrheal illness in developing countries. Efficient delivery of these toxins requires ETEC to engage target host enterocytes. This engagement is accomplished using a variety of pathovar-specific and conserved E. coli adhesin molecules as well as plasmid encoded colonization factors. Some of these adhesins undergo significant transcriptional modulation as ETEC encounter intestinal epithelia, perhaps suggesting that they cooperatively facilitate interaction with the host...
May 22, 2017: PLoS Neglected Tropical Diseases
https://www.readbyqxmd.com/read/28531214/suspected-lynch-syndrome-associated-msh6-variants-a-functional-assay-to-determine-their-pathogenicity
#12
Hellen Houlleberghs, Anne Goverde, Jarnick Lusseveld, Marleen Dekker, Marco J Bruno, Fred H Menko, Arjen R Mensenkamp, Manon C W Spaander, Anja Wagner, Robert M W Hofstra, Hein Te Riele
Lynch syndrome (LS) is a hereditary cancer predisposition caused by inactivating mutations in DNA mismatch repair (MMR) genes. Mutations in the MSH6 DNA MMR gene account for approximately 18% of LS cases. Many LS-associated sequence variants are nonsense and frameshift mutations that clearly abrogate MMR activity. However, missense mutations whose functional implications are unclear are also frequently seen in suspected-LS patients. To conclusively diagnose LS and enroll patients in appropriate surveillance programs to reduce morbidity as well as mortality, the functional consequences of these variants of uncertain clinical significance (VUS) must be defined...
May 22, 2017: PLoS Genetics
https://www.readbyqxmd.com/read/28530095/rational-design-of-bacillus-coagulans-nl01-l-arabinose-isomerase-and-using-its-f279i-variant-in-d-tagatose-production
#13
Zhaojuan Zheng, Wending Mei, Meijuan Xia, Qin He, Jia Ouyang
D-tagatose is a prospective functional sweetener that can be produced by L-arabinose isomerase (AI) from D-galactose. To improve the activity of AI toward D-galactose, the AI of Bacillus coagulans was rationally designed based on molecular modeling and docking. After alanine scanning and site-saturation mutagenesis, variant F279I that exhibited improved activity toward D-galactose was obtained. The optimal temperature and pH of F279I were determined to be 50°C and 8.0, respectively. This variant possessed 1...
May 22, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/28528958/investigation-of-calcium-dependent-activity-and-conformational-dynamics-of-zebra-fish-12-lipoxygenase
#14
Monica Mittal, Mahmudul Hasan, Navisraj Balagunaseelan, Alexander Fauland, Craig Wheelock, Olof Rådmark, Jesper Z Haeggström, Agnes Rinaldo-Matthis
BACKGROUND: A 12-lipoxygenase in zebra fish (zf12-LOX) was found to be required for normal embryonic development and LOXs are of great interest for targeted drug designing. In this study, we investigate the structural-functional aspects of zf12-LOX in response to calcium. METHODS: A soluble version of zf12-LOX was created by mutagenesis. Based on multiple sequence alignment, we mutated the putative calcium-responsive amino acids in N-PLAT domain of soluble zf12-LOX...
May 18, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28528452/tumor-suppressor-protein-p53-exerts-negative-transcriptional-regulation-on-human-sodium-iodide-symporter-gene-expression-in-breast-cancer
#15
Madhura G Kelkar, Bhushan Thakur, Abhishek Derle, Sushmita Chatterjee, Pritha Ray, Abhijit De
PURPOSE: Aberrant expression of human sodium iodide symporter (NIS) in breast cancer (BC) is well documented but the transcription factors (TF) regulating its aberrant expression is poorly known. We identify the presence of three p53 binding sites on the human NIS promoter sequence by conducting genome-wide TF analysis, and further investigate their regulatory role. METHODS: The differences in transcription and translation were measured by real-time PCR, luciferase reporter assay, site-directed mutagenesis, in vivo optical imaging, and chromatin immunoprecipitation...
May 20, 2017: Breast Cancer Research and Treatment
https://www.readbyqxmd.com/read/28527797/mir-26b-promoter-analysis-reveals-regulatory-mechanisms-by-lipid-related-transcription-factors-in-goat-mammary-epithelial-cells
#16
Hui Wang, Jun Luo, Qiuya He, Dawei Yao, Jiao Wu, Juan J Loor
MicroRNA (miRNA) regulate protein abundance and control diverse aspects of cellular processes and biological functions associated with lipid metabolism. MiR-26b and its host gene CTDSP1 regulate triacylglycerol synthesis by synergistically suppressing the insulin-induced gene 1 (INSIG1); however, the direct regulators of miR-26b expression remain unknown. In the present study, we characterized the activity of a novel putative promoter region in miR-26b. Results revealed that promoter activity and miR-26b expression are dynamically regulated by different transcription factors including peroxisome proliferator-activated receptor gamma (PPARG), sterol regulatory element binding transcription factor 1 (SREBF1), and liver X receptor α (LXRα)...
May 17, 2017: Journal of Dairy Science
https://www.readbyqxmd.com/read/28527120/a-new-maltose-inducible-high-performance-heterologous-expression-system-in-bacillus-subtilis
#17
Jie Yue, Gang Fu, Dawei Zhang, Jianping Wen
OBJECTIVES: To improve heterologous proteins production, we constructed a maltose-inducible expression system in Bacillus subtilis. RESULTS: An expression system based on the promoter for maltose utilization constructed in B. subtilis. Successively, to improve the performance of the P malA -derived system, mutagenesis was employed by gradually shortening the length of P malA promoter and altering the spacing between the predicted MalR binding site and the -35 region...
May 19, 2017: Biotechnology Letters
https://www.readbyqxmd.com/read/28527116/genome-editing-in-drosophila-melanogaster-from-basic-genome-engineering-to-the-multipurpose-crispr-cas9-system
#18
REVIEW
Xingjie Ren, Kristof Holsteens, Haiyi Li, Jin Sun, Yifan Zhang, Lu-Ping Liu, Qingfei Liu, Jian-Quan Ni
Nowadays, genome editing tools are indispensable for studying gene function in order to increase our knowledge of biochemical processes and disease mechanisms. The extensive availability of mutagenesis and transgenesis tools make Drosophila melanogaster an excellent model organism for geneticists. Early mutagenesis tools relied on chemical or physical methods, ethyl methane sulfonate (EMS) and X-rays respectively, to randomly alter DNA at a nucleotide or chromosomal level. Since the discovery of transposable elements and the availability of the complete fly genome, specific genome editing tools, such as P-elements, zinc-finger nucleases (ZFNs) and transcription activator-like effector nucleases (TALENs), have undergone rapid development...
May 1, 2017: Science China. Life Sciences
https://www.readbyqxmd.com/read/28526743/systematic-identification-of-functional-residues-of-artemisia-annua-amorpha-4-11-diene-synthase
#19
Xin Fang, Jian-Xu Li, Jin-Quan Huang, You-Li Xiao, Peng Zhang, Xiao-Ya Chen
Terpene synthases (TPSs) are responsible for the extremely diversified and complex structure of terpenoids. Amorpha-4,11-diene synthase (ADS) has a high (90%) fidelity in generating the sesquiterpene precursor for biosynthesis of artemisinin, an antimalarial drug, however, little is known about how active site residues of ADS involved in the carbocation rearrangement and cyclization reactions. Here, we identify seven residues that are key to most of the catalytic steps in ADS. By structural modeling and amino acid sequence alignments of ADS with two functionally relevant sesquiterpene synthases from Artemisia annua, we performed site-directed mutagenesis and found that a single substitution, T296V, impaired the ring closure activity almost completely, and tetra-substitutions (L374Y/L404V/L405I/G439S) led to an enzyme generating 80% monocyclic bisabolyl-type sesquiterpenes, whereas a double mutant (T399L/T447G) showed compromised activity in regioselective deprotonation to yield 34...
May 19, 2017: Biochemical Journal
https://www.readbyqxmd.com/read/28526731/validated-bayesian-differentiation-of-causative-and-passenger-mutations
#20
Frederick R Cross, Michal Breker, Kristi Lieberman
In many contexts, the problem arises of determining which of many candidate mutations is the most likely to be causative for some phenotype. It is desirable to have a way to evaluate this probability that relies as little as possible on previous knowledge, to avoid bias against discovering new genes or functions. We are isolating mutants with blocked cell cycle progression in Chlamydomonas, and determining mutant genome sequences. Due to the intensity of UV mutagenesis required for efficient mutant collection, the mutants contain multiple mutations altering coding sequence...
May 19, 2017: G3: Genes—Genomes—Genetics
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