Part:BBa_K2760003

Mutated soluble gp80: (mutated variant of sIL-6 receptor A228D, N230D, H280S, D281V)

This is a gene that codifies for a soluble modified human gp80, part of the complex for interleukin 6 inflammatory signaling system [1], it also lacks the cytoplasmic and transmembrane amino acidic residues of gp80. This mutation causes the gp80 protein not to bind with gp130 when forming the IL-6-gp80-gp130 complex. It can unite with IL-6 and form the IL-6-alphaReceptor(gp80) complex but not with human gp130, thus acting as an antagonistic complex vs the formation of the IL-6-gp80-gp130 complex, and therefore, blocking inflammation pathways [2].

In an in vivo context, the alpha protein unit (gp80) is responsible for a “low affinity” binding with IL-6, but it is when gp80 and gp130 (beta chain of the same cell receptor complex for IL-6) join that a high affinity complex for IL-6 is formed, thus binding with IL-6 occurs, then inflammation pathways follow [3].

For many cytokine receptors, soluble forms are known to retain binding capacity, and even can act as antagonists by competing with membrane receptors, this has been suggested as a form of therapy for inflammatory related diseases in several studies [3], and even small molecules acting as inhibitors to block gp130 have been presented [4]. On the other hand, soluble forms of gp80 have been previously expressed in E. coli and demonstrated to have biological activity [3].

Using a molecular weight calculator online the protein weight for the amino acid sequence resulted to be 40. 52 kilodaltons [5].

References: [1] Baran P., Hansen S., Waetzig GH., Akbarzadeh M., Lamertz L., Huber HJ., Ahmadian MR., Moll JM., Scheller J. (2018). The balance of interleukin (IL)-6, IL-6·soluble IL-6 receptor (sIL-6R), and IL-6·sIL-6R·sgp130 complexes allows simultaneous classic and trans-signaling. J Biol Chem. doi: 10.1074/jbc.RA117.001163

[2] Salvati, A., Lahm, A., Paonessa, G., Ciliberto, G., Toniatti, C. (1994). Interleukin-6 (IL-6) Antagonism by Soluble IL-6 Receptor α Mutated in the Predicted gp130-binding Interface. The Journal of Biological Chemistry. Vol. 270. No 20. Issue of May 19, pp. 1242-1249, 1995.

[3] Stoyan, T., Stoyan, F., Uwe Michaelis, R.J, Schooltink, H. Van Dam, M., Heinricht, P., STOYAN' (1993). Recombinant soluble human interleukin-6 receptor Expression in Escherichia coli, renaturation and purification.J. Biochemie. EJB 93 064611

[4] Hong, S., Choi, JH., Lee, SY., Park, YH., Park, KY., Lee, JY., Kim, J., Gajulapati, V., Goo, JI., Lee, K., Kim YK., SH., Ahn, SH., Rose-John, S., Heo, TH., Choi, Y. (2015). A Novel Small-Molecule Inhibitor Targeting the IL-6 Receptor β Subunit, Glycoprotein 130. J. Immunol. doi: 10.4049/jimmunol.1402908.

[5]. Molecular weight calculator. Science Gateway. https://www.sciencegateway.org/tools/proteinmw.htm