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Soluble Protein Expression Optimization

In many cases, expression of recombinant proteins often results in insoluble and/or nonfunctional proteins. Here, factors in soluble protein expression optimization and several strategies to improve the solubility of the expressed protein are reviewed.

BiologicsCorp
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Soluble Protein Expression Optimization

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  1. SOLUBLE PROTEIN SOLUBLE PROTEIN EXPRESSION OPTIMIZATION EXPRESSION OPTIMIZATION BiologicsCorp BiologicsCorp www.biologicscorp.com www.biologicscorp.com 1

  2. OUTLINE OUTLINE Factors in soluble protein expression optimization  Codon optimization  Strains  Vectors  Protein synthesis rate  Growth medium  Fusion tags  Co-expression proteins 2

  3. CODON OPTIMIZATION CODON OPTIMIZATION  Adjust codon usage frequency and enhance mRNA stability  State-of-art algorithms  Pre-computed software from a predicted group of highly expressed genes Parameters • Avoided restriction enzymes • Non-coding regions • Motifs • Codon usage bias • GC content • mRNA secondary structure • Repeat sequence 3

  4. STRAINS STRAINS BL21 (DE3) BL21 Star (DE3) Rosetta (DE3) • Routine protein expression • Deficient in proteases Lon and OmpT, which increase protein stability • Promotes high mRNA stability and protein yield • T7 promoter-based expression systems • Contain rare codons (AUA,AGG,AGA,CU A,CC,GGA) in E. coli • Adjust codon usage bias and enhance protein expression BL21 (DE3) pLysS OrigamiB (DE3) BL21-CodonPlus (DE3) • Contain extra copies of tRNA genes • Improve expression of heterologous proteins from organisms without AT- or GC-rich genomes • Combine desirable characteristics of BL21, Tuner™, and Origami strains in one strain • Ideal for expressing protein with disulfide bonds • Suppress basal expression • Ideal for toxic protein expression 4

  5. VECTORS VECTORS pET vector • Powerful: high expression levels, tight control over basal expression • Versatile: choices of tags and multiple cloning sites • Rapid: convenient restriction sites for sub cloning, one-step purification pCold vector pCold vector • Efficient: improved protein expression at low temperatures In-house fusion vector • Multiple vectors available to improve protein expression level 5

  6. PROTEIN SYNTHESIS RATE PROTEIN SYNTHESIS RATE  Multiple strategies slows down translation process for optimized protein solubility. Use a weak promoter Use a low copy number plasmid Lower growth temperature Lower inducer concentration 6

  7. GROWTH MEDIUM GROWTH MEDIUM  Special chemicals in media serve play important roles in protein proper folding and protein stability. Add buffer Control pH fluctuation in the growth medium Add Glucose Repress induction of the lac promoter by lactose Add polyols Work as osmo-prectants and stabilize protein structure Add prosthetic groups or co- factors Trace metals, minerals, and vitamins may contribute to protein proper folding and stability. 7

  8. FUSION TAGS FUSION TAGS  A large variety of protein tags are available for improving protein stability and facilitating soluble protein expression. Tag Size Protein Key features GST 211 aa Glutathione-S-transferase Easy to manipulate MBP 396 aa Maltose-binding protein Available for purification NusA 495 aa N-utilization substance Increase membrane protein solubility Trx 109 aa Thioredoxin Simple initial purification step SUMO ~100 aa Small ubiquitin modifier High specific cleavage sites 8

  9. CO CO- -EXPRESSION PROTEINS EXPRESSION PROTEINS  Chaperones: transiently interact with protein folding intermediates and contribute to protein expression  GroES-GroEL  DnaK-DnaJ-GrpE  ClpB  Trigger factor  Heat shock proteins  Foldases: accelerate rate-limiting steps in the folding process  Peptidylprolylcis/trans isomerases (PPI's)  Disulfide oxidoreductase (DsbA) and disulfide isomerase (DsbC)  Protein disulfide isomerase (PDI) 9

  10. PROJECT PROCESS PROJECT PROCESS  Soluble protein expression optimization process  Codon optimized gene synthesis  Expression condition optimization  Scale-up production  Purification and delivery 10

  11. CONTACT US CONTACT US  BiologicsCorp (BIC) owns a self contained and complete optimization platform for supernatant protein expression. We also offer tag-free protein production, endotoxin removal, and high-throughput protein production services. Please feel free to contact us for more information about the services. Email: Sales@BiologicsCorp.com   Online Form Tel: +1 (317) 703-0614 Fax: +1 (855) 427-1516 REFERENCES REFERENCES Berrow, Nick S., et al. "Recombinant protein expression and solubility screening in Escherichia coli: a comparative study." Acta Crystallographica 62.10(2006):1218–1226. Redwan, El Rashdy M. "The optimal gene sequence for optimal protein expression in Escherichia coli: principle requirements." Arab J Biotechnol 9(2006):493-510. Malhotra, A. "Tagging for protein expression. " Methods in Enzymology 463(2009):239-58.    11

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