Fusion of the antiferritin antibody VL domain to barnase results in enhanced solubility and altered pH stability

Sergey P. Martsev, Yaroslav I. Tsybovsky, Oleg A. Stremovskiy, Sergey G. Odintsov, Taras G. Balandin, Paolo Arosio, Zinaida I. Kravchuk, Sergey M. Deyev

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

Chimeric immunotoxins that combine antigen recognition domains of antibodies and cytotoxic RNases have attracted much attention in recent years as potential targeted agents for cancer immunotherapy. In an attempt to obtain a structurally minimized immunofusion for folding/stability studies, we constructed the chimeric protein VL-barnase. The chimera comprises a small cytotoxic enzyme barnase, ribonuclease from Bacillus amyloliquefaciens, fused to the C-terminus of the light chain variable domain (VL) of the anti-human ferritin monoclonal antibody F11. While the individual VL domain was expressed in Escherichia coli as insoluble protein packed into inclusion bodies, its fusion to barnase resulted in a significant (∼70%) fraction of soluble protein, with only a minor insoluble fraction (∼30%) packed into inclusion bodies. The in vivo solubilizing effect of barnase was also observed in vitro and suggests a chaperone-like role that barnase exerted with regard to the N-terminal VL domain. Cytoplasmic VL-barnase was analyzed for structural and functional properties. The dimeric state of the chimeric protein was demonstrated by size-exclusion chromatography, thus indicating that fusion to barnase did not abrogate the intrinsic dimerization propensity of the VL domain. Ferritin-binding affinity and specificity in terms of constants of association with isoferritins were identical for the isolated VL domain and its barnase fusion, and RNase activity remained unchanged after the fusion. Intrinsic fluorescence spectra showed a fully compact tertiary structure of the fusion protein. However, significantly altered pH stability of the fusion protein versus individual VL and barnase was shown by the pH-induced changes in both intrinsic fluorescence and binding of ANS. Together, the results indicate that VL-barnase retained the antigen-binding affinity, specificity and RNase activity pertinent to the two individual constituents, and that their fusion into a single-chain chimeric protein resulted in an altered tertiary fold and pH stability.

Original languageEnglish
Pages (from-to)85-93
Number of pages9
JournalProtein Engineering, Design and Selection
Volume17
Issue number1
DOIs
Publication statusPublished - Jan 2004
Externally publishedYes

Fingerprint

Antibodies
Solubility
Fusion reactions
Proteins
Antigens
Ferritins
Ribonucleases
Fluorescence
Inclusion Bodies
Monoclonal antibodies
Dimerization
Size exclusion chromatography
Bacilli
Bacillus amyloliquefaciens ribonuclease
Escherichia coli
Immunotoxins
Enzymes
Protein Stability
Association reactions
Tertiary Protein Structure

Keywords

  • Chaperone-like function
  • Immunotoxin
  • Protein stability
  • RNase
  • VL domain

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Medicine(all)
  • Biochemistry
  • Molecular Biology

Cite this

Fusion of the antiferritin antibody VL domain to barnase results in enhanced solubility and altered pH stability. / Martsev, Sergey P.; Tsybovsky, Yaroslav I.; Stremovskiy, Oleg A.; Odintsov, Sergey G.; Balandin, Taras G.; Arosio, Paolo; Kravchuk, Zinaida I.; Deyev, Sergey M.

In: Protein Engineering, Design and Selection, Vol. 17, No. 1, 01.2004, p. 85-93.

Research output: Contribution to journalArticle

Martsev, SP, Tsybovsky, YI, Stremovskiy, OA, Odintsov, SG, Balandin, TG, Arosio, P, Kravchuk, ZI & Deyev, SM 2004, 'Fusion of the antiferritin antibody VL domain to barnase results in enhanced solubility and altered pH stability', Protein Engineering, Design and Selection, vol. 17, no. 1, pp. 85-93. https://doi.org/10.1093/protein/gzh011
Martsev, Sergey P. ; Tsybovsky, Yaroslav I. ; Stremovskiy, Oleg A. ; Odintsov, Sergey G. ; Balandin, Taras G. ; Arosio, Paolo ; Kravchuk, Zinaida I. ; Deyev, Sergey M. / Fusion of the antiferritin antibody VL domain to barnase results in enhanced solubility and altered pH stability. In: Protein Engineering, Design and Selection. 2004 ; Vol. 17, No. 1. pp. 85-93.
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abstract = "Chimeric immunotoxins that combine antigen recognition domains of antibodies and cytotoxic RNases have attracted much attention in recent years as potential targeted agents for cancer immunotherapy. In an attempt to obtain a structurally minimized immunofusion for folding/stability studies, we constructed the chimeric protein VL-barnase. The chimera comprises a small cytotoxic enzyme barnase, ribonuclease from Bacillus amyloliquefaciens, fused to the C-terminus of the light chain variable domain (VL) of the anti-human ferritin monoclonal antibody F11. While the individual VL domain was expressed in Escherichia coli as insoluble protein packed into inclusion bodies, its fusion to barnase resulted in a significant (∼70{\%}) fraction of soluble protein, with only a minor insoluble fraction (∼30{\%}) packed into inclusion bodies. The in vivo solubilizing effect of barnase was also observed in vitro and suggests a chaperone-like role that barnase exerted with regard to the N-terminal VL domain. Cytoplasmic VL-barnase was analyzed for structural and functional properties. The dimeric state of the chimeric protein was demonstrated by size-exclusion chromatography, thus indicating that fusion to barnase did not abrogate the intrinsic dimerization propensity of the VL domain. Ferritin-binding affinity and specificity in terms of constants of association with isoferritins were identical for the isolated VL domain and its barnase fusion, and RNase activity remained unchanged after the fusion. Intrinsic fluorescence spectra showed a fully compact tertiary structure of the fusion protein. However, significantly altered pH stability of the fusion protein versus individual VL and barnase was shown by the pH-induced changes in both intrinsic fluorescence and binding of ANS. Together, the results indicate that VL-barnase retained the antigen-binding affinity, specificity and RNase activity pertinent to the two individual constituents, and that their fusion into a single-chain chimeric protein resulted in an altered tertiary fold and pH stability.",
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