Structural insights into tyrosine sulfation of CCR5 by human tyrosylprotein sulfotransferase-1.

Post-translational sulfation of the chemokine receptor CCR5 is involved in crucial biological processes such as viral infection and chemokine signaling. This sulfation can occur at the N-terminal tyrosine residues (Y3, Y10, Y14, and Y15) of CCR5 and is catalyzed by human tyrosylprotein sulfotransferases (hTPSTs) within the Golgi lumen. However, the detailed molecular mechanism by which these tyrosine residues are sulfated remains unresolved. To elucidate the mechanism, we determined the crystal structure of a soluble domain of hTPST1 bound to the sulfate donor product 3'-phosphoadenosine 5'-phosphate (PAP) and a modified 18-residue CCR5 peptide designed to isolate the Y3-centered binding mode, at 3.2 Å resolution, with six peptide residues ordered. This structure defines key interactions consistent with Y3 sulfation and is consistent with previous biochemical data. Based on the crystal structure and prior knowledge, we constructed peptide docking models for Y10, Y14, and Y15 sulfation, as well as full-length hTPST1-PAP-CCR5 docking models. The crystal structure provides experimental insight into Y3 recognition, whereas the docking models provide testable hypotheses for how the other sulfation sites may be accommodated in the context of CCR5.