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Protein Engineering, Design & Selection: PEDS

Shubhasish Goswami, Shibashis Das, Supratim Datta
Most β-glucosidases are subjected to inhibition by the final hydrolysis product glucose resulting in the accumulation of cellobiose and oligosaccharides. This accumulated cellobiose and oligosaccharides further inhibit the activities of endoglucanase and cellobiohydrolases, resulting in the inhibition of cellulose degradation and a more expensive biofuel. To elucidate the mechanism(s) of glucose tolerance, we designed and characterised six mutations of a moderately glucose-tolerant β-glucosidase (H0HC94) from the mesophilic bacterium Agrobacterium tumefaciens 5A...
July 1, 2017: Protein Engineering, Design & Selection: PEDS
Nixon Niyonzima, Abigail R Lambert, Rachel Werther, Harshana De Silva Feelixge, Pavitra Roychoudhury, Alexander L Greninger, Daniel Stone, Barry L Stoddard, Keith R Jerome
The combination of yeast surface display and flow cytometric analyses and selections is being used with increasing frequency to alter specificity of macromolecular recognition, including both protein-protein and protein-nucleic acid interactions. Here we describe the use of yeast surface display and cleavage-dependent flow cytometric assays to increase the specificity of an engineered meganuclease. The re-engineered meganuclease displays a significantly tightened specificity profile, while binding its cognate target site with a slightly lower, but still sub-nanomolar affinity...
July 1, 2017: Protein Engineering, Design & Selection: PEDS
Silke Flindt Badino, Jenny Kim Bathke, Trine Holst Sørensen, Michael Skovbo Windahl, Kenneth Jensen, Günther H J Peters, Kim Borch, Peter Westh
Various cellulases consist of a catalytic domain connected to a carbohydrate-binding module (CBM) by a flexible linker peptide. The linker if often strongly O-glycosylated and typically has a length of 20-50 amino acid residues. Functional roles, other than connecting the two folded domains, of the linker and its glycans, have been widely discussed, but experimental evidence remains sparse. One of the most studied cellulose degrading enzymes is the multi-domain cellobiohydrolase Cel7A from Hypocrea jecorina...
July 1, 2017: Protein Engineering, Design & Selection: PEDS
Martin Klinger
The nonspecific binding of certain therapeutic antibodies to tissues or to soluble biomolecules can accelerate their clearance from the circulation and undermine their benefit to patients. This article proposes that tandem amino acid repeat sequences in antibody hypervariable segments, particularly the complementarity determining regions (CDRs), can enhance this off-target binding. This hypothesis is based on two sets of observations. First, in a limited number of cases, antibodies with clusters of amino acid repeats in their CDRs have significantly higher clearance rates in experimental animals than otherwise identical antibodies without the repeats...
July 1, 2017: Protein Engineering, Design & Selection: PEDS
Richard Obexer, Moritz Pott, Cathleen Zeymer, Andrew D Griffiths, Donald Hilvert
No abstract text is available yet for this article.
July 1, 2017: Protein Engineering, Design & Selection: PEDS
Svetlana A Korban, Kirill S Bobrov, Maria A Maynskova, Stanislav N Naryzhny, Olga L Vlasova, Elena V Eneyskaya, Anna A Kulmisnkaya
Sulfatases are a family of enzymes (sulfuric ester hydrolases, EC 3.1.6.-) that catalyze the hydrolysis of a wide array of sulfate esters. To date, despite the discovery of many sulfatase genes and the accumulation of data on numerous sulfated molecules, the number of characterized enzymes that are key players in sulfur metabolism remains extremely limited. While mammalian sulfatases are well studied due to their involvement in a wide range of normal and pathological biological processes, lower eukaryotic sulfatases, especially fungal sulfatases, have not been thoroughly investigated at the biochemical and structural level...
July 1, 2017: Protein Engineering, Design & Selection: PEDS
Fernando García-Guevara, Iris Bravo, Claudia Martínez-Anaya, Lorenzo Segovia
Consensus engineering has been used to design more stable variants using the most frequent amino acid at each site of a multiple sequence alignment; sometimes consensus engineering modifies function, but efforts have mainly been focused on studying stability. Here we constructed a consensus Rossmann domain for the Shikimate dehydrogenase enzyme; separately we decided to switch the cofactor specificity through rational design in the Escherichia coli Shikimate dehydrogenase enzyme and then analyzed the effect of consensus mutations on top of our design...
June 13, 2017: Protein Engineering, Design & Selection: PEDS
Michaela L McNiff, Jennifer S Chadwick
Biologics can be an improvement to small molecule drugs, providing high specificity for an identified target, lowering toxicity and limiting side effects. To achieve effective delivery, the biologic must have sufficient time to reach the target tissue. A prolonged half-life in the circulating environment is desired, but often serum stability is limited by proteases. Proteolysis in the serum causes degradation and inactivation as the biologic is fragmented and more rapidly cleared from the body. To improve the circulating half-life, large, hydrophilic polymers may be conjugated or stable fusion tags may be engineered to increase the effective size of the peptide and to hinder degradation by proteases...
June 1, 2017: Protein Engineering, Design & Selection: PEDS
Julian Ihssen, Dagmara Jankowska, Thomas Ramsauer, Renate Reiss, Ronny Luchsinger, Luzia Wiesli, Mark Schubert, Linda Thöny-Meyer, Greta Faccio
Laccases and laccase-like multi-copper oxidases (LMCOs) are versatile and robust biocatalysts applied in a variety of oxidative processes, and various studies have attempted to improve their catalytic activity. Here we report the engineering of a bacterial LMCO for enhanced oxidation of the lignin-related compound guaiacol by a combination of structure-guided mutagenesis and DNA shuffling. Mutant L9 showed a 1.39 mM Km for guaiacol and a 2.5-fold increase in turnover rate (kcat/Km = 2.85·104 M-1s-1).
June 1, 2017: Protein Engineering, Design & Selection: PEDS
Andreas Schwarte, Maika Genz, Lilly Skalden, Alberto Nobili, Clare Vickers, Okke Melse, Remko Kuipers, Henk-Jan Joosten, Jan Stourac, Jaroslav Bendl, Jon Black, Peter Haase, Coos Baakman, Jiri Damborsky, Uwe Bornscheuer, Gert Vriend, Hanka Venselaar
The NewProt protein engineering portal is a one-stop-shop for in silico protein engineering. It gives access to a large number of servers that compute a wide variety of protein structure characteristics supporting work on the modification of proteins through the introduction of (multiple) point mutations. The results can be inspected through multiple visualizers. The HOPE software is included to indicate mutations with possible undesired side effects. The Hotspot Wizard software is embedded for the design of mutations that modify a proteins' activity, specificity, or stability...
June 1, 2017: Protein Engineering, Design & Selection: PEDS
Philbert Ip, Priya Roy Sharda, Anna Cunningham, Sumon Chakrabartty, Vijay Pande, Avijit Chakrabartty
In many cases of familial amyotrophic lateral sclerosis (ALS), mutant forms of the Cu,Zn superoxide dismutase protein (SOD1) misfold and aggregate in motor neurons. Monomers of the normally homodimeric SOD1 have been found in patient tissue, presymptomatic mouse models of ALS, and in vitro misfolding assays which suggests that monomerization might be an early step in the pathological SOD1 misfolding pathway. In this study, we targeted the dimer interface with small molecules that might act as chemical chaperones to stabilize the native dimer and prevent downstream misfolding and aggregation...
June 1, 2017: Protein Engineering, Design & Selection: PEDS
Sarah C Stainbrook, Jessica S Yu, Michael P Reddick, Neda Bagheri, Keith E J Tyo
The promiscuity of G-protein-coupled receptors (GPCRs) has broad implications in disease, pharmacology and biosensing. Promiscuity is a particularly crucial consideration for protein engineering, where the ability to modulate and model promiscuity is essential for developing desirable proteins. Here, we present methodologies for (i) modifying GPCR promiscuity using directed evolution and (ii) predicting receptor response and identifying important peptide features using quantitative structure-activity relationship models and grouping-exhaustive feature selection...
June 1, 2017: Protein Engineering, Design & Selection: PEDS
Maxim Rossmann, Sandra J Greive, Tommaso Moschetti, Michael Dinan, Marko Hyvönen
Protein-protein interactions (PPIs) determine a wide range of biological processes and analysis of these dynamic networks is increasingly becoming a mandatory tool for studying protein function. Using the globular ATPase domain of recombinase RadA as a scaffold, we have developed a peptide display system (RAD display), which allows for the presentation of target peptides, protein domains or full-length proteins and their rapid recombinant production in bacteria. The design of the RAD display system includes differently tagged versions of the scaffold, which allows for flexibility in the protein purification method, and chemical coupling for small molecule labeling or surface immobilization...
June 1, 2017: Protein Engineering, Design & Selection: PEDS
Cindy Zer, Kendra N Avery, Kassondra Meyer, Leah Goodstein, Krzysztof P Bzymek, Gagandeep Singh, John C Williams
We have previously identified a cyclic peptide called meditope which binds to the central cavity of the Fab portion of cetuximab and shown that this peptide binding site can be grafted, or 'meditope-enabled', onto trastuzumab. This peptide has been shown to act as a hitch for the non-covalent attachment of imaging agents to meditope-enabled antibodies. Herein, we explore the process of grafting this peptide binding site onto M5A, an anti-CEA antibody in clinical trials for cancer diagnostics. In order to explore the contributions of the amino acids, we sequentially introduced pairs of amino acid substitutions into the Fab and then we reverse-substituted key residues in the presence of the other substitutions...
June 1, 2017: Protein Engineering, Design & Selection: PEDS
M Ultsch, A Braisted, H R Maun, C Eigenbrot
The well-studied B-domain from Staphylococcal protein A is a 59 amino acid three-helix bundle that binds the Fc portion of IgG with a dissociation constant of ~35 nM. The B-domain variant bearing a Gly to Ala mutation (=Z-domain) has been the subject of efforts to minimize a domain's size while retaining its function. We report X-ray crystallographic characterization of three steps in such a process using complexes with Fc: the full three-helix Z-domain, a 34 amino acid two-helix version called Z34C and a 13 amino acid single helix stabilized with an exo-helix tether, called LH1...
May 5, 2017: Protein Engineering, Design & Selection: PEDS
Masoumeh Nosrati, Sara Solbak, Olle Nordesjö, Mikael Nissbeck, Daniel F A R Dourado, Ken G Andersson, Mohammad Reza Housaindokht, John Löfblom, Anders Virtanen, U Helena Danielson, Samuel Coulbourn Flores
The interaction between the Staphylococcal Protein A (SpA) domain B (the basis of the Affibody) molecule and the Fc of IgG is key to the use of Affibodies in affinity chromatography and in potential therapies against certain inflammatory diseases. Despite its importance and four-decade history, to our knowledge this interaction has never been affinity matured. We elucidate reasons why single-substitutions in the SpA which improve affinity to Fc may be very rare, and also discover substitutions which potentially serve several engineering purposes...
May 3, 2017: Protein Engineering, Design & Selection: PEDS
Ronit Rosenfeld, Ron Alcalay, Adva Mechaly, Gideon Lapidoth, Eyal Epstein, Chanoch Kronman, Sarel J Fleishman, Ohad Mazor
While potent monoclonal antibodies against ricin were introduced over the years, the question whether increasing antibody affinity enables better toxin neutralization was not fully addressed yet. The aim of this study was to characterize the contribution of antibody affinity to the ricin neutralization potential of the antibody. cHD23 monoclonal antibody that targets the toxin B-subunit and interferes with its binding to membranal receptors, was isolated. In order to create antibody clones with improved affinity toward ricin, a scFv-phage display library containing mutated versions of the variable regions of cHD23 was constructed and clones with improved binding of ricin were isolated...
May 3, 2017: Protein Engineering, Design & Selection: PEDS
Lei Chen, Yuanyuan Duan, Lorenzo Benatuil, William B Stine
Clear and accurate understanding of diversity in antibody complementarity-determining regions (CDRs) is critical for antibody discovery and engineering. Previous observations of antibody CDR-H3 diversity were based on analyzing available antibody sequences in the public databases. The results may not accurately reflect that of natural antibody repertoire due to erroneous species annotation and the presence of man-made CDR loop diversity in public antibody sequence databases. In this study, in a precisely controlled germline context, we explored the relationship between amino acid composition and CDR-H3 length using 5518 unique productively rearranged human VH3-23*01 gene sequences...
May 3, 2017: Protein Engineering, Design & Selection: PEDS
Magali Tanghe, Barbara Danneels, Matthias Last, Koen Beerens, Ingeborg Stals, Tom Desmet
Lytic polysaccharide monooxygenases (LPMOs) are crucial components of cellulase mixtures but their stability has not yet been studied in detail, let alone been engineered for industrial applications. In this work, we have evaluated the importance of disulfide bridges for the thermodynamic stability of Streptomyces coelicolor LPMO10C. Interestingly, this enzyme was found to retain 34% of its activity after 2-h incubation at 80°C while its apparent melting temperature (Tm) is only 51°C. When its three disulfide bridges were broken, however, irreversible unfolding occurred and no residual activity could be detected after a similar heat treatment...
May 1, 2017: Protein Engineering, Design & Selection: PEDS
Dong Hee Chung, Sarah C Potter, Ammon C Tanomrat, Krishnakumar M Ravikumar, Michael D Toney
Powerful, facile new ways to create libraries of site-directed mutants are demonstrated. These include: (1) one-pot-PCR, (2) multi-pot-PCR, and (3) split-mix-PCR. One-pot-PCR uses mutant oligonucleotides to generate megaprimers in situ, and it was used to randomly incorporate 28 mutations in a gabT gene in a single reaction. In more difficult cases, multi-pot-PCR can be employed: mutant megaprimers are synthesized individually, then combined in a single mutagenesis PCR. This method was used to incorporate 14 out of 15 mutations in a pabB gene...
May 1, 2017: Protein Engineering, Design & Selection: PEDS
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