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Site directed mutations

Joshua H K Tam, M Rebecca Cobb, Claudia Seah, Stephen H Pasternak
The amyloid hypothesis posits that the production of β-amyloid (Aβ) aggregates leads to neurodegeneration and cognitive decline associated with AD. Aβ is produced by sequential cleavage of the amyloid precursor protein (APP) by β- and γ-secretase. While nascent APP is well known to transit to the endosomal/ lysosomal system via the cell surface, we have recently shown that APP can also traffic to lysosomes intracellularly via its interaction with AP-3. Because AP-3 interacts with cargo protein via interaction with tyrosine motifs, we mutated the three tyrosines motif in the cytoplasmic tail of APP...
2016: PloS One
Monika B Dolinska, Nicole Kus, Katie Farney, Paul T Wingfield, Brian P Brooks, Yuri V Sergeev
: Oculocutaneous albinism Type 1 (OCA1) is an autosomal recessive disorder caused by mutations in the tyrosinase gene. Two subtypes of OCA1 have been described: severe OCA1A with complete absence of tyrosinase activity and less severe OCA1B with residual tyrosinase activity. Here, we characterize the recombinant human tyrosinase intra-melanosomal domain and mutant variants, which mimic genetic changes in both subtypes of OCA1 patients. Proteins were prepared using site-directed mutagenesis, expressed in insect larvae, purified by chromatography, and characterized by enzymatic activities- tryptophan fluorescence, and Gibbs free energy changes...
October 24, 2016: Pigment Cell & Melanoma Research
Bharathkumar Inturi, Gurubasavaraj V Pujar, Madhusudhan N Purohit
Mycobacterium tuberculosis enoyl-ACP reductase (InhA) has been validated as a promising target for antitubercular agents. Isoniazid (INH), the most prescribed drug to treat tuberculosis (TB), inhibits a NADH-dependent InhA that provides precursors of mycolic acids, which are components of the mycobacterial cell wall. It is a pro-drug that needs activation to form the inhibitory INH-NAD adduct by KatG coding for catalase-peroxidase. The INH resistance of M. tuberculosis is caused by mutations in KatG, which may lead to multidrug-resistant TB (MDR-TB)...
October 24, 2016: Archiv der Pharmazie
Kathleen M Clark, Jermaine L Jenkins, Nadia Fedoriw, Mark E Dumont
The function and localization of proteins and peptides containing C-terminal "CaaX" (Cys-aliphatic-aliphatic-anything) sequence motifs are modulated by post-translational attachment of isoprenyl groups to the cysteine sulfhydryl, followed by proteolytic cleavage of the aaX amino acids. The zinc metalloprotease ZMPSTE24 is one of two enzymes known to catalyze this cleavage. The only identified target of mammalian ZMPSTE24 is prelamin A, the precursor to the nuclear scaffold protein lamin A. ZMPSTE24 also cleaves prelamin A at a second site 15 residues upstream from the CaaX site...
October 24, 2016: Protein Science: a Publication of the Protein Society
Agnieszka Fiszer, Marianna E Ellison-Klimontowicz, Wlodzimierz J Krzyzosiak
Polyglutamine (polyQ) diseases comprise a group of nine genetic disorders that are caused by the expansion of the CAG triplet repeat, which encodes glutamine, in unrelated single genes. Various oligonucleotide (ON)-based therapeutic approaches have been considered for polyQ diseases. The very attractive CAG repeat-targeting strategy offers selective silencing of the mutant allele by directly targeting the mutation site. CAG repeat-targeting miRNA-like siRNAs have been shown to specifically inhibit the mutant gene expression, and their characteristic feature is the formation of mismatches in their interactions with the target site...
October 21, 2016: Acta Biochimica Polonica
Kristin Bösch, Lamprinos Frantzeskakis, Miroslav Vraneš, Jörg Kämper, Kerstin Schipper, Vera Göhre
Gene deletion plays an important role in the analysis of gene function. One of the most efficient methods to disrupt genes in a targeted manner is the replacement of the entire gene with a selectable marker via homologous recombination. During homologous recombination, exchange of DNA takes place between sequences with high similarity. Therefore, linear genomic sequences flanking a target gene can be used to specifically direct a selectable marker to the desired integration site. Blunt ends of the deletion construct activate the cell's DNA repair systems and thereby promote integration of the construct either via homologous recombination or by non-homologous-end-joining...
September 30, 2016: Journal of Visualized Experiments: JoVE
Pierre E Affaticati, Shao-Bo Dai, Panwajee Payongsri, Helen C Hailes, Kai Tittmann, Paul A Dalby
The S385Y/D469T/R520Q variant of E. coli transketolase was evolved previously with three successive smart libraries, each guided by different structural, bioinformatical or computational methods. Substrate-walking progressively shifted the target acceptor substrate from phosphorylated aldehydes, towards a non-phosphorylated polar aldehyde, a non-polar aliphatic aldehyde, and finally a non-polar aromatic aldehyde. Kinetic evaluations on three benzaldehyde derivatives, suggested that their active-site binding was differentially sensitive to the S385Y mutation...
October 21, 2016: Scientific Reports
Ka-Yee Au, Wei-Wei Shi, Shuai Qian, Zhong Zuo, Pang-Chui Shaw
To improve the pharmacological properties of maize ribosome-inactivating protein (maize RIP) for targeting HIV-infected cells, the previously engineered TAT-fused active form of maize RIP (MOD) was further engineered for cysteine-directed PEGylation. In this work, two potential antigenic sites, namely Lys-78 and Lys-264, were identified. They were mutated to cysteine residue and conjugated with PEG5k or PEG20k. The resultant PEG derivatives of MOD variants were examined for ribosome-inactivating activity, circulating half-life and immunogenicity...
October 17, 2016: Toxins
Priyanka Dutta, Ahnaf Siddiqui, Mohsen Botlani, Sameer Varma
Nipah is an emerging paramyxovirus that is of serious concern to human health. It invades host cells using two of its membrane proteins-G and F. G binds to host ephrins and this stimulates G to activate F. Upon activation, F mediates virus-host membrane fusion. Here we focus on mechanisms that underlie the stimulation of G by ephrins. Experiments show that G interacts with ephrin and F through separate sites located on two different domains, the receptor binding domain (RBD) and the F activation domain (FAD)...
October 18, 2016: Biophysical Journal
Zhonglan Wu, Lijia Cui, Weiming Zhao, Dongzhi Yang, Hui Chen, Ruiqing Wang, Xuemin Wang, Linqi Zhang, Tianhua He
BACKGROUND: Current prevalence and genotype distribution of hepatitis C virus (HCV) infection remain unknown in Ningxia, northwest China. METHODS: From June to December 2013, 13,022 individuals were screened in Ningxia HIV/AIDS Sentinel Surveillance System, with their demographic features collected and serum samples tested for HCV antibody. Sero-positive drug users were further subjected to sequencing of NS5B and Core regions of HCV. RESULTS: The anti-HCV prevalence was 0...
October 18, 2016: Virology Journal
Mir A Hossain, Yong Shen, Isaac Knudson, Shaleen Thakur, Jared R Stees, Yi Qiu, Betty S Pace, Kenneth R Peterson, Jörg Bungert
Reactivation of γ-globin expression has been shown to ameliorate disease phenotypes associated with mutations in the adult β-globin gene, including sickle cell disease. Specific mutations in the promoter of the γ-globin genes are known to prevent repression of the genes in the adult and thus lead to hereditary persistence of fetal hemoglobin. One such hereditary persistence of fetal hemoglobin is associated with a sequence located 567 bp upstream of the Gγ-globin gene which assembles a GATA-containing repressor complex...
October 18, 2016: Molecular Therapy. Nucleic Acids
Peter F Davies, Elisabetta Manduchi, Christian J Stoeckert, Yi-Zhou Jiang
Hemodynamics creates a constantly changing physical and chemical environment to which the arterial endothelium is exquisitely sensitive. Biomechanical stresses are intrinsic to blood flow characteristics and blood pressure and therefore are important considerations in hypertension. Near branching anatomical sites in arteries, blood flow separates from the main flow to undergo complex multi-directional characteristics for a part of each cardiac cycle (collectively referred to as disturbed flow). Atherosclerosis and aneurysmal pathology develop preferentially at disturbed flow locations, particularly when an additional cardiovascular risk factor such as hypercholesterolemia or high blood pressure are present...
September 2016: Journal of Hypertension
Juan Wang, Hiroyuki Kobori, Yuki Shibayama, Daisuke Nakano, Hirofumi Hitomi, Akira Nishiyama
OBJECTIVE: Previous studies have shown that angiotensinogen (AGT) synthesis is enhanced by high glucose (HG) in rat renal proximal tubular cells. We aimed to investigate the glucose-responsive elements within human AGT (hAGT) promoter in human immortalized proximal tubular HK-2 cells. DESIGN AND METHOD: HK-2 cells were treated with normal glucose (NG: 5.5 mmol/L) and high glucose (HG: 15 mmol/L). Human AGT promoter region was cloned from -4358 to +122. Consecutive 5'-end deletion mutant constructs and different site-direct mutagenesis products were transfected into HK-2, followed by promoter activity measurement by dual luciferase assay...
September 2016: Journal of Hypertension
Valeria Ascoli, Ilaria Cozzi, Simona Vatrano, Stefania Izzo, Jessica Giorcelli, Elisa Romeo, Caterina Carnovale-Scalzo, Lucia Rosalba Grillo, Francesco Facciolo, Paolo Visca, Mauro Papotti, Luisella Righi
Familial malignant mesothelioma clusters are ideal candidates to explore BAP1 genomic status as a predisposing risk factor. We report data on BAP1 analysis in four families with multiple mesothelioma cases to investigate possible BAP1 alterations associated with an inherited cancer syndrome. We also recorded family history of cancer and assessed asbestos exposure. By genomic direct sequencing, we found no evidence of a BAP1 germline mutation in tumor DNA samples (one mesothelioma per family: n = 3 epithelioid; n = 1 biphasic)...
September 2016: Cancer Genetics
Hao Zhang, Hua Yue, Chun Wang, Weiwei Hu, Jiemei Gu, Jinwei He, Wenzhen Fu, Yunqiu Hu, Miao Li, Zhenlin Zhang
Osteogenesis imperfecta (OI) is an inherited connective tissue disorder characterized by brittle bone fractures. The aim of the present study was to investigate the pathogenic gene mutation spectrum and clinical manifestations of mutations in collagen type I, alpha 1 (COL1A1) and collagen type I, alpha 2 (COL1A2) genes in Chinese patients with OI. A total of 61 unrelated Chinese OI patients with COL1A1 and COL1A2 mutations were recruited. All the exons and the exon-intron boundaries of the COL1A1 and COL1A2 genes were amplified and directly sequenced and lumbar spine bone mineral density was measured by dual‑energy X‑ray absorptiometry...
October 12, 2016: Molecular Medicine Reports
John D Hainsworth, F Anthony Greco
BACKGROUND: Molecular cancer classifier assays are being used with increasing frequency to predict tissue of origin and direct site-specific therapy for patients with carcinoma of unknown primary site (CUP). OBJECTIVE: We postulated some CUP patients predicted to have non-small-cell lung cancer (NSCLC) by molecular cancer classifier assay may have anaplastic lymphoma kinase (ALK) rearranged tumors, and benefit from treatment with ALK inhibitors. METHODS: We retrospectively reviewed CUP patients who had the 92-gene molecular cancer classifier assay (CancerTYPE ID; bioTheranostics, Inc...
March 2016: Drugs—Real World Outcomes
Chen Zhang, Cassandra L Miller, Rakshya Gorkhali, Juan Zou, Kenneth Huang, Edward M Brown, Jenny J Yang
Ca(2+)-sensing receptors (CaSRs) play a central role in regulating extracellular calcium concentration ([Ca(2+)]o) homeostasis and many (patho)physiological processes in multiple organs. This regulation is orchestrated by a cooperative response to extracellular stimuli such as small changes in Ca(2+), Mg(2+), amino acids, and other ligands. In addition, CaSR is a pleiotropic receptor regulating several intracellular signaling pathways, including calcium mobilization and intracellular calcium oscillation. Nearly 200 mutations and polymorphisms have been found in CaSR in relation to a variety of human disorders associated with abnormal Ca(2+) homeostasis...
2016: Frontiers in Physiology
Nicolas Rodrigue, Nicolas Lartillot
Codon substitution models have traditionally attempted to uncover signatures of adaptation within protein-coding genes by contrasting the rates of synonymous and nonsynonymous substitutions. Another modeling approach, known as the mutation-selection framework, attempts to explicitly account for selective patterns at the amino acid level, with some approaches allowing for heterogeneity in these patterns across codon sites. Under such a model, substitutions at a given position occur at the neutral or nearly-neutral rate when they are synonymous, or when they correspond to replacements between amino acids of similar fitness; substitutions from high to low (low to high) fitness amino acids have comparatively low (high) rates...
October 15, 2016: Molecular Biology and Evolution
Uros Kuzmanov, Hongbo Guo, Diana Buchsbaum, Jake Cosme, Cynthia Abbasi, Ruth Isserlin, Parveen Sharma, Anthony O Gramolini, Andrew Emili
Phospholamban (PLN) plays a central role in Ca(2+) homeostasis in cardiac myocytes through regulation of the sarco(endo)plasmic reticulum Ca(2+)-ATPase 2A (SERCA2A) Ca(2+) pump. An inherited mutation converting arginine residue 9 in PLN to cysteine (R9C) results in dilated cardiomyopathy (DCM) in humans and transgenic mice, but the downstream signaling defects leading to decompensation and heart failure are poorly understood. Here we used precision mass spectrometry to study the global phosphorylation dynamics of 1,887 cardiac phosphoproteins in early affected heart tissue in a transgenic R9C mouse model of DCM compared with wild-type littermates...
October 14, 2016: Proceedings of the National Academy of Sciences of the United States of America
Cristiano S Mota, Ana Maria D Gonçalves, Daniele de Sanctis
DR2231 from Deinococcus radiodurans was previously functionally and structurally characterized as an all-α NTP pyrophosphohydrolase with specific dUTPase activity. dUTPases have a central role in the regulation of dUTP intracellular levels and dTTP nucleotide metabolism. DR2231 presents a conserved di-metal catalytic site, similar to the all-α dimeric dUTPases, but contrary to these enzymes, it is unable to process dUDP. In this article we present functional and structural evidence of single-point mutations that affect directly or indirectly the enzyme catalysis and provide a complete description of the all-α NTP pyrophosphohydrolase mechanism...
October 14, 2016: FEBS Journal
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