1BOM

THREE-DIMENSIONAL STRUCTURE OF BOMBYXIN-II, AN INSULIN-RELATED BRAIN-SECRETORY PEPTIDE OF THE SILKMOTH BOMBYX MORI: COMPARISON WITH INSULIN AND RELAXIN

Summary for 1BOM

• Entry DOI: 10.2210/pdb1bom/pdb
• Descriptor: BOMBYXIN-II,BOMBYXIN A-2, BOMBYXIN-II,BOMBYXIN A-6 (2 entities in total)
• Functional Keywords: insulin-like brain-secretory peptide
• Biological source: Bombyx mori (domestic silkworm); More
• Total number of polymer chains: 2
• Total formula weight: 5315.07

Authors

Nagata, K.,Hatanaka, H.,Kohda, D.,Inagaki, F. (deposition date: 1994-07-21, release date: 1994-11-01, Last modification date: 2024-10-16)

Primary citation

Nagata, K.,Hatanaka, H.,Kohda, D.,Kataoka, H.,Nagasawa, H.,Isogai, A.,Ishizaki, H.,Suzuki, A.,Inagaki, F.
Three-dimensional solution structure of bombyxin-II an insulin-like peptide of the silkmoth Bombyx mori: structural comparison with insulin and relaxin.
J.Mol.Biol., 253:749-758, 1995

PubMed Abstract: The three-dimensional solution structure of bombyxin-II, an insulin-like two-chain peptide produced by the brain of the silkworm Bombyx mori, has been determined by simulated annealing calculations based on 535 distance constraints and 24 torsion-angle constraints derived from NMR data and three distance constraints of the disulfide bonds. To our knowledge, this is the first three-dimensional structure determined for an invertebrate insulin-related peptide. The root-mean-square deviations between the best 10 structures and the mean structure are 0.58(+/- 0.15) A for the backbone heavy atoms (N, C alpha, C) and 1.03(+/- 0.18) A for all non-hydrogen atom if less well-defined N and C termini (A1, A20, B(-2) to B4 and B23 to B25) are excluded. The overall main-chain structure of bombyxin-II is similar to that of insulin. However, there are significant conformational and functional differences in their B-chain C-terminal parts. The B-chain C-terminal part of bombyxin-II adopts an extension of the B-chain central helix like that of relaxin and is not required for bombyxin activity, while the corresponding part of insulin adopts a sharp turn and a beta-strand and is essential for insulin activity. This structure demonstrates that bombyxin-II is more closely related to relaxin than to insulin, and suggests that insulin might have evolved the additional receptor-recognition site in the B-chain C-terminal beta-strand to distinguish itself from bombyxin and relaxin. The structure of bombyxin-II thus provides novel insights into the receptor recognition and divergent molecular evolution of insulin-superfamily peptides.

PubMed: 7473749
DOI: 10.1006/jmbi.1995.0588

Experimental method

SOLUTION NMR