Proteome-Wide Characterization of Phosphorylation-Induced Conformational Changes in Breast Cancer

Because of the close
link between protein function and protein
folding stability, knowledge about phosphorylation-induced protein
folding stability changes can lead to a better understanding of the
functional effects of protein phosphorylation. Here, the stability
of proteins from rates of oxidation (SPROX) and limited proteolysis
(LiP) techniques are used to compare the conformational properties
of proteins in two MCF-7 cell lysates including one that was and one
that was not dephosphorylated with alkaline phosphatase. A total of
168 and 251 protein hits were identified with dephosphorylation-induced
stability changes using the SPROX and LiP techniques, respectively.
Many protein hits are previously known to be differentially phosphorylated
or differentially stabilized in different human breast cancer subtypes,
suggesting that the phosphorylation-induced stability changes detected
in this work are disease related. The SPROX hits were enriched in
proteins with aminoacyl-tRNA ligase activity. These enriched protein
hits included many aminoacyl-tRNA synthetases (aaRSs), which are known
from previous studies to have their catalytic activity modulated by
phosphorylation. The SPROX results revealed that the magnitudes of
the destabilizing effects of dephoshporylation on the different aaRSs
were directly correlated with their previously reported aminoacylation
activity change upon dephosphorylation. This substantiates the close
link between protein folding and function.