title: The existence of multiple conformers of interleukin-21 directs engineering of a superpotent analogue.
abstract: The high resolution three-dimensional structure of human interleukin (hIL)-21 has been resolved by heteronuclear NMR spectroscopy. Overall, the hIL-21 structure is dominated by a well defined central four-helical bundle, arranged in an up-up-down-down topology, as observed for other cytokines. A segment of the hIL-21 molecule that includes the third helical segment, helix C, is observed to exist in two distinct and interchangeable states. In one conformer, the helix C segment is presented in a regular, alpha-helical conformation, whereas in the other conformer, this segment is largely disordered. A structure-based sequence alignment of hIL-21 with receptor complexes of the related cytokines, interleukin-2 and -4, implied that this particular segment is involved in receptor binding. An hIL-21 analog was designed to stabilize the region around helix C through the introduction of a segment grafted from hIL-4. This novel hIL-21 analog was demonstrated to exhibit a 10-fold increase in potency in a cellular assay.
authors.affiliation: Novo Nordisk A/S, Biopharmaceuticals Research Unit, DK-2760 Måløv, Denmark. kbaa@novonordisk.com
authors.forename: Kent
authors.initials: K
authors.lastname: Bondensgaard
authors.forename: Jens
authors.initials: J
authors.lastname: Breinholt
authors.forename: Dennis
authors.initials: D
authors.lastname: Madsen
authors.forename: Diana Højmark
authors.initials: DH
authors.lastname: Omkvist
authors.forename: Lishan
authors.initials: L
authors.lastname: Kang
authors.forename: Anne
authors.initials: A
authors.lastname: Worsaae
authors.forename: Peter
authors.initials: P
authors.lastname: Becker
authors.forename: Christine Bruun
authors.initials: CB
authors.lastname: Schiødt
authors.forename: Siv A
authors.initials: SA
authors.lastname: Hjorth
mesh_terms: D000595:Amino Acid Sequence; D002460:Cell Line; D018360:Crystallography, X-Ray; D006801:Humans; D007378:Interleukins / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008958:Models, Molecular; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D011487:Protein Conformation; D015202:Protein Engineering; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D013696:Temperature; D000098546:Interleukin-21
chemical_list: D007378:Interleukins; D000098546:Interleukin-21