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The solution conformation of tubulin‐β(422–434)‐NH 2 and its Nac‐DATADEQG‐NH 2 fragment based on nmr
Author(s) -
Otter Albin,
Scott Paul G.,
Maccioni Ricardo B.,
Kotovych George
Publication year - 1991
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360310410
Subject(s) - chemistry , conformational isomerism , nuclear magnetic resonance spectroscopy , histone octamer , nuclear overhauser effect , crystallography , spectroscopy , stereochemistry , proton , molecule , two dimensional nuclear magnetic resonance spectroscopy , chemical shift , hydrogen bond , side chain , organic chemistry , biochemistry , physics , quantum mechanics , nucleosome , gene , histone , polymer
The solution conformation of tubulin‐β(422–434)‐NH 2 (YQQYQDATADEQG‐NH 2 ) and its Nac‐DATADEQG‐NH 2 fragment has been studied by two‐dimensional 1 H‐nmr spectroscopy in CD 3 OH/H 2 O (90/10 v/v) at neutral and low pH. The 13 amino acid peptide is a segment of the C‐terminal region of tubulin, and is directly involved in the selective binding site with microtubule‐associated proteins MAP‐2 and the τ protein. Based on correlated spectroscopy, total correlation spectroscopy, and rotating frame nuclear Over‐hauser effect spectroscopy experiments, a complete assignment of all proton resonances was achieved, and the conformation of the backbone could be deduced from coupling constants, NH temperature coefficients, and nuclear Overhauser effects. The spectroscopic evidence indicates that the T 8 ‐Q 12 section of both molecules forms one complete α‐helical turn, stabilized by a NH(Q 12 )‐CO(T 8 ) hydrogen bond. Furthermore, strong pH‐dependent backfolding of the E 11 side chain to its own NH proton was found. In addition, close proximity between the aromatic side chains of Y 1 , Y 4 , and the α‐helical part, resulting in some substantial chemical shift changes when comparing the entire 13‐mer with the octamer, could be explained in terms of a nonclassical kink in the DATA section. The conformational space is dominated by extended structures and the nonextended conformers are only a minor, yet spectroscopically clearly discernible entity. The presence of the α‐helical region at the C‐terminus of the 13‐mer is important because binding studies of this peptide with MAP‐2 indicate that the D 10 ‐E 11 ‐Q 12 ‐G 13 fragment is critical for the binding interaction.