A salt bridge of the C-terminal carboxyl group regulates PHPT1 substrate affinity and catalytic activity.

ABSTRACT: PHPT1 is a histidine phosphatase that modulates signaling in eukaryotes through its catalytic activity. Here, we present an analysis of the structure and dynamics of PHPT1 through a combination of solution NMR, molecular dynamics, and biochemical experiments. We identify a salt bridge formed between the R78 guanidinium moiety and the C-terminal carboxyl group on Y125 that is critical for ligand binding. Disruption of the salt bridge by appending a glycine residue at the C-terminus (G126) leads to a decrease in catalytic activity and binding affinity for the pseudo substrate, para-nitrophenylphosphate (pNPP), as well as the active site inhibitor, phenylphosphonic acid (PPA). We show through NMR chemical shift, ¹⁵N relaxation measurements, and analysis of molecular dynamics trajec

SUBMITTER: Zavala E 

PROVIDER: S-EPMC11094782 | biostudies-literature | 2024 Jun

REPOSITORIES: biostudies-literature