Role of the C-terminus in the activity, conformation, and stability of interleukin-6.


Two murine interleukin-6 (mIL-6) variants were constructed using the polymerase chain reaction (PCR), one lacking the last five residues (183-187) at the C-terminus (pMC5) and another with the last five residues of mIL-6 substituted by the corresponding residues of human IL-6 (pMC5H). The growth stimulatory activity of pMC5 on the mouse hybridoma cell line 7TD1 was < 0.05% of mIL-6, whereas pMC5H and mIL-6 were equipotent. The loss of biological activity of pMC5 correlated with its negligible receptor binding affinity on 7TD1 cells, while the binding of pMC5H was comparable to that of mIL-6. Both pMC5 and pMC5H, like mIL-6, failed to interact with recombinant soluble human IL-6 receptor when assayed by surface plasmon resonance-based biosensor analysis. These studies suggest that the C-terminal seven amino acids of human IL-6, alone, do not define species specificity for receptor binding. A variety of biophysical techniques, as well as the binding of a conformational-specific monoclonal antibody, indicated that the global fold of the mIL-6 variants was similar to that of mIL-6, although small changes in the NMR spectra, particularly for pMC5, were observed. Some of these changes involved residues widely separated in the primary structure. For instance, interactions involving Tyr-22 were influenced by the C-terminal amino acids suggesting that the N- and C-termini of mIL-6 are in close proximity. Equilibrium unfolding experiments indicated that pMC5 was 0.8 kcal/mol less stable than mIL-6, whereas pMC5H was 1.4 kcal/mol more stable. These studies emphasize the structural importance of the C-terminal amino acids of IL-6 and suggest that truncation or mutation of this region could lead to small but significant alterations in other regions of the molecule. Study holds ProTherm entries: 9881 Extra Details: biosensor; CD; interleukin-6; mutants; NMR; receptor binding activity

Submission Details

ID: HVnkcKcz

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:39 p.m.

Version: 1

Publication Details
Ward LD;Hammacher A;Zhang JG;Weinstock J;Yasukawa K;Morton CJ;Norton RS;Simpson RJ,Protein Sci. (1993) Role of the C-terminus in the activity, conformation, and stability of interleukin-6. PMID:8401231
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Interleukin-6 P08505 IL6_MOUSE