Synthesis of a tumorspecific single-chain antibody and derivatives in E. coli and COS-1 cells

1997 ◽  
Vol 56 (1-3) ◽  
pp. 191
Author(s):  
S Dincq
2020 ◽  
Vol 89 (1) ◽  
pp. 39-45
Author(s):  
Magdalena Krasna ◽  
Vladimír Celer

Porcine reproductive and respiratory syndrome virus (PRRSV) is a widespread infectious agent in pigs. Nucleocapsid (N) protein of PRRSV has been identified as the most immunodominant viral protein. The main goal of the work was the selection and characterization of a single-chain antibody fragments (scFv) antibody specific to the N protein. Specific scFv antibody clone D5 was selected from the Tomlinson phagemid library and purified by immobilized metal affinity chromatography from the periplasmatic space of E. coli cells. The antibody was then characterized by sequencing and the ability to recognize the native virus N protein by Western blot and competitive ELISA. Pepscan analysis identified the position of the binding epitope between amino acids 62–84 of the N protein. Our study could help to improve the diagnostics and prevention of PRRSV in Central Europe.


2020 ◽  
Author(s):  
Chillel Jawara ◽  
Kirsty L Richards ◽  
Amber R Peswani ◽  
Kelly L Walker ◽  
Lara Nascimento ◽  
...  

Abstract Background: Numerous high-value proteins have been produced in E. coli, and a favoured strategy is to export the protein of interest to the periplasm by means of an N-terminal signal peptide. While the Sec pathway has been extensively used for this purpose, the Tat pathway has potential because it transports fully-folded heterologous proteins. Most studies on the Tat pathway have used the E. coli TorA signal peptide to direct export, because it is highly Tat-specific, unlike many Tat signal peptides which can also function as Sec signal peptides. However, the TorA signal peptide is prone to degradation in the cytoplasm, leading to reduced export rates in some cases. Here, we have tested a range of alternative signal peptides for their ability to direct Tat-dependent export of a single-chain antibody fragment (scFv). Results: We show that the signal peptides of E. coli AmiC, MdoD and YcbK direct efficient export of the scFv by both the Tat and Sec pathways, which may be a disadvantage when Tat-specific export is required. The same applies to the Tat signal peptide of Bacillus subtilis PhoD, which likewise directs efficient export by Sec. We engineered the PhoD signal peptide by introduction of a Lys or Asn residue in the C-terminal domain of the signal peptide, and we show that this substitution renders the signal peptide Tat-specific. These signal peptides, designated PhoDk and PhoDn, direct efficient export of scFv in shake flask and fed-batch fermentation studies, reaching export levels that are well above those obtained with the TorA signal peptide. Culturing in ambr250 bioreactors was used to fine-tune the growth conditions, and the net result was export of the scFv by the Tat pathway at levels of approximately 1g protein/L culture. Conclusions: The new PhoDn and PhoDk signal peptides have significant potential for the export of heterologous proteins by the Tat system.


Toxins ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 509
Author(s):  
Jirawat Khanongnoi ◽  
Siratcha Phanthong ◽  
Onrapak Reamtong ◽  
Anchalee Tungtronchitr ◽  
Wanpen Chaicumpa ◽  
...  

Snake venom-metalloproteinases (SVMPs) are the primary factors that disturb hemostasis and cause hemorrhage in the venomous snake bitten subjects. Kaouthiagin is a unique SVMP that binds and cleaves von Willebrand factor (vWF) at a specific peptide bond leading to inhibition of platelet aggregation, which enhances the hemorrhage. Kaouthiagin is a low abundant venom component of Thai cobra (Naja kaouthia); thus, most horse-derived antivenins used for cobra bite treatment do not contain adequate anti-kaouthiagin. This study aimed to produce human single-chain antibody variable fragments (HuscFvs) that bind to and interfere with kaouthiagin activity for further clinical use. Kaouthiagin was purified from N. kaouthia-holovenom by a single-step gel-filtration chromatography. The purified venom component was used in phage-biopanning to select the kaouthiagin-bound HuscFv-displayed-phage clones from a HuscFv-phage display library. The selected phages were used to infect Escherichia coli bacteria. Soluble HuscFvs expressed by three phage-transformed-E. coli clones interfered with cobra kaouthiagin binding to human vWF. Computerized simulation indicated that HuscFv of two phage-transformed E. coli clones formed contact interface with kaouthiagin residues at or near catalytic site and effectively inhibited fibrinogenolytic activity of the kaouthiagin. The HuscFvs have therapeutic potential as an adjunct of antivenins in treatment of bleeding caused by venomous snakebites.


1997 ◽  
Vol 56 ◽  
pp. 191
Author(s):  
Stéphanie Dincq ◽  
Kristine De Sutter ◽  
Reinhilde Schoonjans ◽  
Roland Contreras ◽  
Walter Fiers

2001 ◽  
Vol 67 (9) ◽  
pp. 3994-4000 ◽  
Author(s):  
Jörg Schäffner ◽  
Jeannette Winter ◽  
Rainer Rudolph ◽  
Elisabeth Schwarz

ABSTRACT Attempts were made to engineer the periplasm of Escherichia coli to an expression compartment of heterologous proteins in their native conformation. As a first approach the low-molecular-size additive l-arginine and the redox compound glutathione (GSH) were added to the culture medium. Addition of 0.4 Ml-arginine and 5 mM reduced GSH increased the yield of a native tissue-type plasminogen activator variant (rPA), consisting of the kringle-2 and the protease domain, and a single-chain antibody fragment (scFv) up to 10- and 37-fold, respectively. A variety of other medium additives also had positive effects on the yield of rPA. In a second set of experiments, the effects of cosecreted ATP-independent molecular chaperones on the yields of native therapeutic proteins were investigated. At optimized conditions, cosecretion of E. coli DnaJ or murine Hsp25 increased the yield of native rPA by a factor of 170 and 125, respectively. Cosecretion of DnaJ also dramatically increased the amount of a second model protein, native proinsulin, in the periplasm. The results of this study are anticipated to initiate a series of new approaches to increase the yields of native, disulfide-bridged, recombinant proteins in the periplasm ofE. coli.


2020 ◽  
Author(s):  
Chillel Jawara ◽  
Kirsty L Richards ◽  
Amber R Peswani ◽  
Kelly L Walker ◽  
Lara Nascimento ◽  
...  

Abstract Background : Numerous high-value proteins have been produced in E. coli, and a favoured strategy is to export the protein of interest to the periplasm by means of an N-terminal signal peptide. While the Sec pathway has been extensively used for this purpose, the Tat pathway has potential because it transports fully-folded heterologous proteins. Most studies on the Tat pathway have used the E. coli TorA signal peptide to direct export, because it is highly Tat-specific, unlike many Tat signal peptides which can also function as Sec signal peptides. However, the TorA signal peptide is prone to degradation in the cytoplasm, leading to reduced export rates in some cases. Here, we have tested a range of alternative signal peptides for their ability to direct Tat-dependent export of a single-chain antibody fragment (scFv). Results : We show that the signal peptides of E. coli AmiC, MdoD and YcbK direct efficient export of the scFv by both the Tat and Sec pathways, which may be a disadvantage when Tat-specific export is required. The same applies to the Tat signal peptide of Bacillus subtilis PhoD, which likewise directs efficient export by Sec. We engineered the PhoD signal peptide by introduction of a Lys or Asn residue in the C-terminal domain of the signal peptide, and we show that this substitution renders the signal peptide Tat-specific. These signal peptides, designated PhoDk and PhoDn, direct efficient export of scFv in shake flask and fed-batch fermentation studies, reaching export levels that are well above those obtained with the TorA signal peptide. Culturing in ambr250 bioreactors was used to fine-tune the growth conditions, and the net result was export of the scFv by the Tat pathway at levels of approximately 1g protein/L culture. Conclusions : The new PhoDn and PhoDk signal peptides have significant potential for the export of heterologous proteins by the Tat system.


2018 ◽  
Vol 40 (4) ◽  
Author(s):  
Dang Thi Ngoc Ha ◽  
Le Thi Thu Hong ◽  
Truong Nam Hai

Single chain variable fragments (scFv) have widely been used in research, diagnosis and treatment, but the scFv is considered as difficult protein for expression in E. coli. In previous studies, we expressed a construction of recombinant single chain variable fragments again antigen specific for blood type A (antiA-scFv) individually or fused with Trx or SUMO. However, soluble fraction was low abandant and only approximately 40% when fused with Trx, the other cases were expressed in form of inclusion body. Therefore, it was difficult for purification, refolding and activity assesment. In thispaper, we demonstrated a suitable construction for soluble production of antiA-scFv fused with SUMO (SM/antiA-scFv) in presence of chaparones. Under fermentation with 0.1 mM IPTG at 20oC, the SM/antiA-scFv was entirely expressed in soluble form. Importantly, after cleavage from SUMO with SUMOprotease, antiA-scFv was still maintained in the supernatant fraction. Therefore, it can help ensure bioactivity and is useful for purification process. To the best of our knowledge, this is the first report showing soluble recombinant scFv fused with SUMO in presence of chaperone for determination of blood group antigens. Thus, this result facilitates the optimal study of soluble expression, purification and bioactivity determination of the antiA-scFv recombinant antibody. 


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