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Phosphorylation alters backbone conformational preferences of serine and threonine peptides
Author(s) -
Kim SuYeon,
Jung Youngae,
Hwang GeumSook,
Han Hogyu,
Cho Minhaeng
Publication year - 2011
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.23148
Subject(s) - polyproline helix , threonine , phosphorylation , serine , chemistry , peptide , circular dichroism , peptide conformation , stereochemistry , conformational isomerism , biochemistry , molecule , organic chemistry
Despite the notion that a control of protein function by phosphorylation works mainly by inducing its conformational changes, the phosphorylation effects on even small peptide conformation have not been fully understood yet. To study its possible effects on serine and threonine peptide conformations, we recently carried out pH‐ and temperature‐dependent circular dichroism (CD) as well as 1 H NMR studies of the phosphorylated serine and threonine peptides and compared them with their unphosphorylated analogs. In the present article, by performing the self‐consistent singular value decomposition analysis of the temperature‐dependent CD spectra and by analyzing the 3 J(H N ,H α ) coupling constants extracted from the NMR spectra, the populations of the polyproline II (PPII) and β‐strand conformers of the phosphorylated Ser and Thr peptides are determined. As temperature is increased, the β‐strand populations of both phosphorylated serine and threonine peptides increase. However, the dependences of PPII/β‐strand population ratio on pH are different for these two cases. The phosphorylation of the serine peptide enhances the PPII propensity, whereas that of the threonine peptide has the opposite effect. This suggests that the serine and threonine phosphorylations can alter the backbone conformational propensity via direct but selective intramolecular hydrogen‐bonding interactions with the peptide NH groups. This clearly indicates that the phosphoryl group actively participates in modulating the peptide backbone conformations. Proteins 2011; © 2011 Wiley‐Liss, Inc.