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iterative mutagenesis

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https://www.readbyqxmd.com/read/28693917/biocatalysts-for-the-pharmaceutical-industry-created-by-structure-guided-directed-evolution-of-stereoselective-enzymes
#1
REVIEW
Guangyue Li, Jian-Bo Wang, Manfred T Reetz
Enzymes have been used for a long time as catalysts in the asymmetric synthesis of chiral intermediates needed in the production of therapeutic drugs. However, this alternative to man-made catalysts has suffered traditionally from distinct limitations, namely the often observed wrong or insufficient enantio- and/or regioselectivity, low activity, narrow substrate range, and insufficient thermostability. With the advent of directed evolution, these problems can be generally solved. The challenge is to develop and apply the most efficient mutagenesis methods which lead to highest-quality mutant libraries requiring minimal screening...
May 11, 2017: Bioorganic & Medicinal Chemistry
https://www.readbyqxmd.com/read/28649005/crispr-cas9-coupled-recombineering-for-metabolic-engineering-of-corynebacterium-glutamicum
#2
Jae Sung Cho, Kyeong Rok Choi, Cindy Pricilia Surya Prabowo, Jae Ho Shin, Dongsoo Yang, Jaedong Jang, Sang Yup Lee
Genome engineering of Corynebacterium glutamicum, an important industrial microorganism for amino acids production, currently relies on random mutagenesis and inefficient double crossover events. Here we report a rapid genome engineering strategy to scarlessly knock out one or more genes in C. glutamicum in sequential and iterative manner. Recombinase RecT is used to incorporate synthetic single-stranded oligodeoxyribonucleotides into the genome and CRISPR/Cas9 to counter-select negative mutants. We completed the system by engineering the respective plasmids harboring CRISPR/Cas9 and RecT for efficient curing such that multiple gene targets can be done iteratively and final strains will be free of plasmids...
July 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28571627/directed-evolution-of-thermomyces-lanuginosus-lipase-to-enhance-methanol-tolerance-for-efficient-production-of-biodiesel-from-waste-grease
#3
Kaiyuan Tian, Kee Tai, Bryan Jian Wei Chua, Zhi Li
Engineering a methanol tolerant lipase is of great importance in biodiesel production. Here, the first semi-rational method for directed enzyme evolution to enhance methanol tolerance by targeting high B-factor residues for iterative saturation mutagenesis (ISM) is reported. The best double mutant, TLL-S105C/D27R, retained 71% of its original activity after incubation in methanol, showing 30% greater methanol tolerance than TLL. TLL-S105C/D27R also displayed 27% higher activity over TLL. Structure modelling suggested that the increased stability of TLL-S105C/D27R was caused by the formation of a new hydrogen bond which stabilized the protein structure...
May 19, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28562590/genetic-wiring-maps-of-single-cell-protein-states-reveal-an-off-switch-for-gpcr-signalling
#4
Markus Brockmann, Vincent A Blomen, Joppe Nieuwenhuis, Elmer Stickel, Matthijs Raaben, Onno B Bleijerveld, A F Maarten Altelaar, Lucas T Jae, Thijn R Brummelkamp
As key executers of biological functions, the activity and abundance of proteins are subjected to extensive regulation. Deciphering the genetic architecture underlying this regulation is critical for understanding cellular signalling events and responses to environmental cues. Using random mutagenesis in haploid human cells, we apply a sensitive approach to directly couple genomic mutations to protein measurements in individual cells. Here we use this to examine a suite of cellular processes, such as transcriptional induction, regulation of protein abundance and splicing, signalling cascades (mitogen-activated protein kinase (MAPK), G-protein-coupled receptor (GPCR), protein kinase B (AKT), interferon, and Wingless and Int-related protein (WNT) pathways) and epigenetic modifications (histone crotonylation and methylation)...
June 8, 2017: Nature
https://www.readbyqxmd.com/read/28559484/finding-the-needle-in-the-haystack-the-use-of-microfluidic-droplet-technology-to-identify-vitamin-secreting-lactic-acid-bacteria
#5
Jun Chen, Mike Vestergaard, Thomas Glasdam Jensen, Jing Shen, Martin Dufva, Christian Solem, Peter Ruhdal Jensen
Efficient screening technologies aim to reduce both the time and the cost required for identifying rare mutants possessing a phenotype of interest in a mutagenized population. In this study, we combined a mild mutagenesis strategy with high-throughput screening based on microfluidic droplet technology to identify Lactococcus lactis variants secreting vitamin B2 (riboflavin). Initially, we used a roseoflavin-resistant mutant of L. lactis strain MG1363, JC017, which secreted low levels of riboflavin. By using fluorescence-activated droplet sorting, several mutants that secreted riboflavin more efficiently than JC017 were readily isolated from the mutagenesis library...
May 30, 2017: MBio
https://www.readbyqxmd.com/read/28508385/improving-the-temperature-characteristics-and-catalytic-efficiency-of-a-mesophilic-xylanase-from-aspergillus-oryzae-aoxyn11a-by-iterative-mutagenesis-based-on-in-silico-design
#6
Xue-Qing Li, Qin Wu, Die Hu, Rui Wang, Yan Liu, Min-Chen Wu, Jian-Fang Li
To improve the temperature characteristics and catalytic efficiency of a glycoside hydrolase family (GHF) 11 xylanase from Aspergillus oryzae (AoXyn11A), its variants were predicted based on in silico design. Firstly, Gly(21) with the maximum B-factor value, which was confirmed by molecular dynamics (MD) simulation on the three-dimensional structure of AoXyn11A, was subjected to site-saturation mutagenesis. Thus, one variant with the highest thermostability, AoXyn11A(G21I), was selected from the mutagenesis library, E...
December 2017: AMB Express
https://www.readbyqxmd.com/read/28469274/crispr-cpf1-assisted-genome-editing-of-corynebacterium-glutamicum
#7
Yu Jiang, Fenghui Qian, Junjie Yang, Yingmiao Liu, Feng Dong, Chongmao Xu, Bingbing Sun, Biao Chen, Xiaoshu Xu, Yan Li, Renxiao Wang, Sheng Yang
Corynebacterium glutamicum is an important industrial metabolite producer that is difficult to genetically engineer. Although the Streptococcus pyogenes (Sp) CRISPR-Cas9 system has been adapted for genome editing of multiple bacteria, it cannot be introduced into C. glutamicum. Here we report a Francisella novicida (Fn) CRISPR-Cpf1-based genome-editing method for C. glutamicum. CRISPR-Cpf1, combined with single-stranded DNA (ssDNA) recombineering, precisely introduces small changes into the bacterial genome at efficiencies of 86-100%...
May 4, 2017: Nature Communications
https://www.readbyqxmd.com/read/28159567/probing-the-excitonic-landscape-of-the-chlorobaculum-tepidum-fenna-matthews-olson-fmo-complex-a-mutagenesis-approach
#8
Rafael G Saer, Valentyn Stadnytskyi, Nikki C Magdaong, Carrie Goodson, Sergei Savikhin, Robert E Blankenship
In this paper we report the steady-state optical properties of a series of site-directed mutants in the Fenna-Matthews-Olson (FMO) complex of Chlorobaculum tepidum, a photosynthetic green sulfur bacterium. The FMO antenna complex has historically been used as a model system for energy transfer due to the water-soluble nature of the protein, its stability at room temperature, as well as the availability of high-resolution structural data. Eight FMO mutants were constructed with changes in the environment of each of the bacteriochlorophyll a pigments found within each monomer of the homotrimeric FMO complex...
April 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28096331/one-step-design-of-a-stable-variant-of-the-malaria-invasion-protein-rh5-for-use-as-a-vaccine-immunogen
#9
Ivan Campeotto, Adi Goldenzweig, Jack Davey, Lea Barfod, Jennifer M Marshall, Sarah E Silk, Katherine E Wright, Simon J Draper, Matthew K Higgins, Sarel J Fleishman
Many promising vaccine candidates from pathogenic viruses, bacteria, and parasites are unstable and cannot be produced cheaply for clinical use. For instance, Plasmodium falciparum reticulocyte-binding protein homolog 5 (PfRH5) is essential for erythrocyte invasion, is highly conserved among field isolates, and elicits antibodies that neutralize in vitro and protect in an animal model, making it a leading malaria vaccine candidate. However, functional RH5 is only expressible in eukaryotic systems and exhibits moderate temperature tolerance, limiting its usefulness in hot and low-income countries where malaria prevails...
January 31, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28074221/exploring-the-thermostable-properties-of-halohydrin-dehalogenase-from-agrobacterium-radiobacter-ad1-by-a-combinatorial-directed-evolution-strategy
#10
Zhiyun Wu, Wenfeng Deng, Yapei Tong, Qian Liao, Dongmin Xin, Huashun Yu, Juan Feng, Lixia Tang
As a crucial factor for biocatalysts, protein thermostability often arises from a combination of factors that are often difficult to rationalize. In this work, the thermostable nature of halohydrin dehalogenase from Agrobacterium radiobacter AD1 (HheC) was systematically explored using a combinatorial directed evolution approach. For this, a mutagenesis library of HheC mutants was first constructed using error-prone PCR with low mutagenesis frequency. After screening approximately 2000 colonies, six mutants with eight mutation sites were obtained...
April 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28004455/engineering-central-metabolism-a-grand-challenge-for-plant-biologists
#11
EDITORIAL
Lee J Sweetlove, Jens Nielsen, Alisdair R Fernie
The goal of increasing crop productivity and nutrient-use efficiency is being addressed by a number of ambitious research projects seeking to re-engineer photosynthetic biochemistry. Many of these projects will require the engineering of substantial changes in fluxes of central metabolism. However, as has been amply demonstrated in simpler systems such as microbes, central metabolism is extremely difficult to rationally engineer. This is because of multiple layers of regulation that operate to maintain metabolic steady state and because of the highly connected nature of central metabolism...
December 22, 2016: Plant Journal: for Cell and Molecular Biology
https://www.readbyqxmd.com/read/27812824/development-of-bacillus-subtilis-mutants-to-produce-tryptophan-in-pigs
#12
Karin Bjerre, Mette D Cantor, Jan V Nørgaard, Hanne D Poulsen, Karoline Blaabjerg, Nuria Canibe, Bent B Jensen, Birgitte Stuer-Lauridsen, Bea Nielsen, Patrick M F Derkx
OBJECTIVES: To generate tryptophan-overproducing Bacillus subtilis strains for in situ use in pigs, to reduce the feed cost for farmers and nitrogen pollution. RESULTS: A novel concept has been investigated-to generate B. subtilis strains able to produce tryptophan (Trp) in situ in pigs. Mutagenesis by UV was combined with selection on Trp and purine analogues in an iterative process. Two mutants from different wild types were obtained, mutant 1 (M1) produced 1 mg Trp/l and mutant 2 (M2) 14 mg Trp/l...
February 2017: Biotechnology Letters
https://www.readbyqxmd.com/read/27746324/iteratively-improving-natamycin-production-in-streptomyces-gilvosporeus-by-a-large-operon-reporter-based-strategy
#13
Yemin Wang, Zhengsheng Tao, Hualiang Zheng, Fei Zhang, Qingshan Long, Zixin Deng, Meifeng Tao
Many high-value secondary metabolites are assembled by very large multifunctional polyketide synthases or non-ribosomal peptide synthetases encoded by giant genes, for instance, natamycin production in an industrial strain of Streptomyces gilvosporeus. In this study, a large operon reporter-based selection system has been developed using the selectable marker gene neo to report the expression both of the large polyketide synthase genes and of the entire gene cluster, thereby facilitating the selection of natamycin-overproducing mutants by iterative random mutagenesis breeding...
October 13, 2016: Metabolic Engineering
https://www.readbyqxmd.com/read/27645297/rational-design-of-thermostability-in-bacterial-1-3-1-4-%C3%AE-glucanases-through-spatial-compartmentalization-of-mutational-hotspots
#14
Chengtuo Niu, Linjiang Zhu, Xin Xu, Qi Li
Higher thermostability is required for 1,3-1,4-β-glucanase to maintain high activity under harsh conditions in the brewing and animal feed industries. In this study, a comprehensive and comparative analysis of thermostability in bacterial β-glucanases was conducted through a method named spatial compartmentalization of mutational hotspots (SCMH), which combined alignment of homologous protein sequences, spatial compartmentalization, and molecular dynamic (MD) simulation. The overall/local flexibility of six homologous β-glucanases was calculated by MD simulation and linearly fitted with enzyme optimal enzymatic temperatures...
February 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/27401975/high-level-of-spinosad-production-in-the-heterologous-host-saccharopolyspora-erythraea
#15
Jun Huang, Zhen Yu, Mei-Hong Li, Ji-Dong Wang, Hua Bai, Jun Zhou, Yu-Guo Zheng
UNLABELLED: Spinosad, a highly effective insecticide, has an excellent environmental and mammalian toxicological profile. Global market demand for spinosad is huge and growing. However, after much effort, there has been almost no improvement in the spinosad yield from the original producer, Saccharopolyspora spinosa Here, we report the heterologous expression of spinosad using Saccharopolyspora erythraea as a host. The native erythromycin polyketide synthase (PKS) genes in S. erythraea were replaced by the assembled spinosad gene cluster through iterative recombination...
September 15, 2016: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/27312879/the-in-vitro-selection-world
#16
REVIEW
Kenan Jijakli, Basel Khraiwesh, Weiqi Fu, Liming Luo, Amnah Alzahmi, Joseph Koussa, Amphun Chaiboonchoe, Serdal Kirmizialtin, Laising Yen, Kourosh Salehi-Ashtiani
Through iterative cycles of selection, amplification, and mutagenesis, in vitro selection provides the ability to isolate molecules of desired properties and function from large pools (libraries) of random molecules with as many as 10(16) distinct species. This review, in recognition of a quarter of century of scientific discoveries made through in vitro selection, starts with a brief overview of the method and its history. It further covers recent developments in in vitro selection with a focus on tools that enhance the capabilities of in vitro selection and its expansion from being purely a nucleic acids selection to that of polypeptides and proteins...
August 15, 2016: Methods: a Companion to Methods in Enzymology
https://www.readbyqxmd.com/read/27234138/semi-rational-engineering-of-cytochrome-cyp153a-from-marinobacter-aquaeolei-for-improved-%C3%AF-hydroxylation-activity-towards-oleic-acid
#17
Yan Duan, Lina Ba, Jianwei Gao, Xianxing Gao, Dunming Zhu, René M de Jong, Daniel Mink, Iwona Kaluzna, Zhanglin Lin
ω-Hydroxy oleic acid is an important intermediate for the synthesis of certain polyesters and polyamides. In this study, a functional CYP153A/putidaredoxin (Pdx)/putidaredoxin reductase (Pdr) hybrid system was engineered for improved ω-hydroxylation activity towards oleic acid. By the combination of site-directed saturation mutagenesis (SDSM) and iterative saturation mutagenesis (ISM), a best mutant (Variant II) was obtained with mutations at two sites (S120 and P165) at the Pdx interaction interface with CYP153A, and one site (S453) in the substrate binding pocket...
October 2016: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/27225474/practical-two-step-synthesis-of-enantiopure-styrene-oxide-through-an-optimized-chemoenzymatic-approach
#18
Kai Wu, Hualei Wang, Lifeng Chen, Haiyang Fan, Zhiqiang Zhao, Dongzhi Wei
Enantiopure styrene oxide (SO) and its derivatives are important building blocks for chiral synthesis. In this study, we developed an attractive "1-pot, 2-step" chemoenzymatic approach for producing enantiopure SO with 100 % theoretical yield. This approach involved asymmetric reduction of α-chloroacetophenone by an alcohol dehydrogenase (ADH; step 1), followed by base-induced ring closure (epoxidation) of enantiopure 2-chloro-1-phenylethanol produced by the ADH (step 2). By-product formation during epoxidation was suppressed to <1 % by adding methyl tert-butyl ether (MTBE) as the second phase...
October 2016: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/27216910/combinatorial-evolution-of-phosphotriesterase-toward-a-robust-malathion-degrader-by-hierarchical-iteration-mutagenesis
#19
Xiao-Jing Luo, Jian Zhao, Chun-Xiu Li, Yun-Peng Bai, Manfred T Reetz, Hui-Lei Yu, Jian-He Xu
Malathion is one of the most widely used organophosphorus pesticides in the United States and developing countries. Herein, we enhanced the degradation rate of malathion starting with a phosphotriesterase PoOPHM2 while also considering thermostability. In the first step, iterative saturation mutagenesis at residues lining the binding pocket (CASTing) was employed to optimize the enzyme active site for substrate binding and activity. Hot spots for enhancing activity were then discovered through epPCR-based random mutagenesis, and these beneficial mutations were then recombined by DNA shuffling...
November 2016: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/27094289/combined-and-iterative-use-of-computational-design-and-directed-evolution-for-protein-ligand-binding-design
#20
Meng Wang, Huimin Zhao
The advantages of computational design and directed evolution are complementary, and only through combined and iterative use of both approaches, a daunting task such as protein-ligand interaction design, can be achieved efficiently. Here, we describe a systematic strategy to combine structure-guided computational design, iterative site saturation mutagenesis, and yeast two-hybrid system (Y2H)-based phenotypic screening to engineer novel and orthogonal interactions between synthetic ligands and human estrogen receptor α (hERα) for the development of novel gene switches...
2016: Methods in Molecular Biology
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