Abstract
Protein tyrosine sulfation is a common post-translational modification that stimulates intercellular or extracellular protein-protein interactions and is responsible for various important biological processes, including coagulation, inflammation, and virus infections. Recently, human P-selectin glycoprotein ligand-1 (PSGL-1) has been shown to serve as a functional receptor for enterovirus 71 (EV71). It has been proposed that the capsid viral protein VP1 of EV71 is directly involved in this specific interaction with sulfated or mutated PSGL-1. Surface-enhanced Raman spectroscopy (SERS) is used to distinguish PSGL-1 and VP1 interactions on an Au nanoporous substrate and identify specific VP1 interaction positions of tyrosine residue sites (46, 48, and 51). The three tyrosine sites in PSGL-1 were replaced by phenylalanine (F), as determined using SERS. A strong phenylalanine SERS signal was obtained in three regions of the mutated protein on the nanoporous substrate. The mutated protein positions at (51F) and (48F, 51F) produced a strong SERS peak at 1599–1666 cm−1, which could be related to a binding with the mutated protein and anti-sulfotyrosine interactions on the nanoporous substrate. A strong SERS effect of the mutated protein and VP1 interactions appeared at (48F), (51F), and (46F, 48F). In these positions, there was less interaction with VP1, as indicated by a strong phenylalanine signal from the mutated protein.
Highlights
Protein tyrosine sulfation (PTS) is a significant post-translational modification that occurs via the tyrosyl protein sulfotransferase (TPST) catalyst through the transfer of the sulfuryl group (SO3 −1 ) from
We investigated sulfated (S) or mutated GST-P-selectin glycoprotein ligand-1 (PSGL-1) and VP1 protein of enterovirus 71 (EV71) interactions and the interaction position of tyrosine residues via SERS spectral changes on an Au nanoporous surface in real time
The protocols used for TPST, PSGL-1, GST-PSGL-1, S-GST-PSGL-1, mutant GST-PSGL-1, and VP-1 of EV71 are explained in our earlier publication [4,17,21]
Summary
Protein tyrosine sulfation (PTS) is a significant post-translational modification that occurs via the tyrosyl protein sulfotransferase (TPST) catalyst through the transfer of the sulfuryl group (SO3 −1 ) from. The specific monitoring of PTS-based PPIs requires a long time and a high concentration due to the instability of sulfated target proteins in real-time applications. The present work utilizes the SERS technique to investigate the interactions between sulfated or mutated GST-PSGL-1 and an antibody or VP1 of EV71 on a nanoplasmonic surface. The high-purity tyrosine sulfation residues were obtained by using the GST fusion tag without affecting TPST activity on GST-PSGL-1. We investigated sulfated (S) or mutated GST-PSGL-1 and VP1 protein of EV71 interactions and the interaction position of tyrosine residues via SERS spectral changes on an Au nanoporous surface in real time. The SERS spectra were used to determine whether the GST-PSGL-1 and VP1 interactions at the three tyrosine residues had different activity abilities after being subjected to PTS.
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