A Phosphoserine−Lysine Salt Bridge within an α-Helical Peptide, the Strongest α-Helix Side-Chain Interaction Measured to Date

Abstract

Phosphorylation is ubiquitous in control of protein activity, yet its effects on protein structure are poorly understood. Here we investigate the effect of serine phosphorylation in the interior of an alpha-helix when a salt bridge is present between the phosphate group and a positively charged side chain (in this case lysine) at i,i + 4 spacing. The stabilization of the helix is considerable and can overcome the intrinsically low preference of phosphoserine for the interior of the helix. The effect is pH dependent, as both the lysine and phosphate groups are titratable, and so calculations are given for several charge combinations. These results, with our previous work, highlight the different, context-dependent effects of phosphorylation in the alpha-helix. The interaction between the phosphate(2)(-) group and the lysine side chain is the strongest yet recorded in helix-coil studies. The results are of interest both in de novo design of peptides and in understanding the structural modes of control by phosphorylation.

How Post‐Translational Modifications Influence Amyloid Formation: A Systematic Study of Phosphorylation and Glycosylation in Model Peptides

“…[32] It was also demonstrated that phosphorylation of a-helices can be stabilizing, but only with appropriate neighboring residues. [33,34] Although steric bulk is an important factor associated with the changed folding behavior of the PP, our results imply that it is not the essential factor because the much larger sugar moiety does not lead to the same result. Calculated van der Waals volumes of the native and modified serine side-chains show that phosphorylation increases the side-chain volume by a factor of two, whereas incorporation of a single galactose residue results in a six-fold increase in volume (see the Supporting Information).…”

Anle138b and related compounds are aggregation specific fluorescence markers and reveal high affinity binding to α-synuclein aggregates

“…The concentrations of the α-synuclein proteins in the fibrillar solutions were determined via measurements of the tyrosine absorption (extinction coefficient at 280 nm 1209 M −1 cm −1 ) [22].…”

Combined Enzymatic and Data Mining Approaches for Comprehensive Phosphoproteome Analyses

“…This proposal was also supported from the retention time behavior of ␣-casein N-acetylated phosphopeptides where an increase in retention time was consistently observed upon AP treatment in contrast to the non-derivatized phosphopeptides. In a similar fashion, a few studies have shown that introduction or removal of a phosphate group completely destroys the stability and conformation of the peptide because salt bridges are disrupted from basic or N-terminal residues (32,33). Conformational studies of phosphopeptide secondary interactions are presently in progress to further characterize possible effects that will reveal a more complete reasoning of the model.…”

“…Highly sensitive detection techniques are required because phosphoproteins represent only a small proportion of any given cell extracts (typically ϳ1-2%) (4). Most conventional methods such as two-dimensional gels, 32 P radioactive labeling, and Western blotting have limited features, which do not enable them to comprehensively profile phosphoproteome change or identify the exact phosphorylation site.…”