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The NMR solution structure of the pheromone E r ‐2 from the ciliated protozoan Euplotes raikovi
Author(s) -
Ottiger M.,
Szyperski T.,
Luginbühl P.,
Ortenzi C.,
Luporini P.,
Bradshaw R. A.,
WÜthrich K.
Publication year - 1994
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.5560030917
Subject(s) - dihedral angle , conformational isomerism , stereochemistry , chemistry , crystallography , residue (chemistry) , tetrapeptide , protein structure , helix (gastropod) , peptide , molecule , hydrogen bond , biology , biochemistry , ecology , organic chemistry , snail
The NMR structure of the pheromone E r ‐2 from the ciliated protozoan Euplotes raikovi has been determined in aqueous solution. The structure of this 40‐residue protein was calculated with the distance geometry program DIANA from 621 distance constraints and 89 dihedral angle constraints; the program OPAL was employed for the energy minimization. For a group of 20 conformers used to characterize the solution structure, the average pairwise RMS deviation from the mean structure calculated for the backbone heavy atoms N, C α , and C′ of residues 3–37 was 0.31 Å. The molecular architecture is dominated by an up‐down‐up bundle of 3 short helices of residues 5–11, 14–20, and 23–33, which is similar to the structures of the homologous pheromones E r ‐1 and E r ‐10. Novel structural features include a well‐defined N‐cap on the first helix, a 1‐residue deletion in the second helix resulting in the formation of a 3 10 ‐helix rather than an α‐helix as found in E r ‐1 and E r ‐10, and the simultaneous presence of 2 different conformations for the C‐terminal tetrapeptide segment, i.e., a major conformation with the Leu 39‐Pro 40 peptide bond in the trans form and a minor conformation with this peptide bond in the cis form.