biostudies-literatureHamid MNational Center for Bigdata and Cloud ComputingHigher Education Commission12771https://www.ebi.ac.uk/biostudies/studies/S-EPMC9659070biostudies-literatureUnknown23(21)The <i>Escherichia coli</i> CheY protein belongs to a large bacterial response regulator superfamily. X-ray hydroxy radical foot-printing with mass spectroscopy (XFMS) has shown that allosteric activation of CheY by its motor target triggers a concerted internalization of aromatic sidechains. We reanalyzed the XFMS data to compare polar versus non-polar CheY residue positions. The polar residues around and including the 57D phosphorylated site had an elevated hydroxy radical reactivity. Bioinformatic measures revealed that a water-mediated hydrogen bond network connected this ring of residues with the central 57D. These residues solvated 57D to energetically stabilize the apo-CheY fold. The abundance of these reactive residues was reduced upon activation. This result was supported by the bInternational journal of molecular sciencesThe Solvation of the <i>E. coli</i> CheY Phosphorylation Site Mapped by XFMS.PMC9659070RF-NCBC-01520-3629/NRPU/R&amp;D/HEC/14/585Khalid MFChaudhary SUHamid MKhan SfalseThe Solvation of the <i>E. coli</i> CheY Phosphorylation Site Mapped by XFMS.The <i>Escherichia coli</i> CheY protein belongs to a large bacterial response regulator superfamily. X-ray hydroxy radical foot-printing with mass spectroscopy (XFMS) has shown that allosteric activation of CheY by its motor target triggers a concerted internalization of aromatic sidechains. We reanalyzed the XFMS data to compare polar versus non-polar CheY residue positions. The polar residues around and including the 57D phosphorylated site had an elevated hydroxy radical reactivity. Bioinformatic measures revealed that a water-mediated hydrogen bond network connected this ring of residues with the central 57D. These residues solvated 57D to energetically stabilize the apo-CheY fold. The abundance of these reactive residues was reduced upon activation. This result was supported by the b2022-01-01T00:00:00Z2022 Oct2025-04-04T13:31:26.655Z2024-12-04T03:14:51.488ZS-EPMC96590703636156410.3390/ijms232112771