New Consensus Features for Tyrosine O-Sulfation Determined by Mutational Analysis

Abstract

Tyrosine sulfation is an ubiquitous modification of proteins synthesized along the secretory pathway. It enhances protein-protein interactions and may be necessary for the bioactivity of secreted proteins and peptides. To predict tyrosine sulfation, a consensus has been proposed based on sequence comparisons of known substrates and on in vitro studies using synthetic peptides. This consensus predicts the presence of acidic residues on the amino-terminal side of the target tyrosine as the key feature. Using site-directed mutagenesis, we have examined the role of residues neighboring the sulfation site of an intact protein, human progastrin, in vivo. The results show that the charge of the residue in the amino-terminal position (؊1) of the tyrosine is critical and can be neutral or acidic, whereas a basic residue abolishes sulfation. In addition, the degree of sulfation is influenced by the residues in positions ؊2 and ؊3. Hence, surprisingly a basic residue in position ؊2 enhances sulfation. Our data suggest a considerably broader range of substrates for the tyrosylprotein sulfotransferase than hitherto assumed and that the tyrosylprotein sulfotransferase is cell-specifically expressed.

Sulfated tyrosines 27 and 29 in the N-terminus of human CXCR3 participate in binding native IP-10

“…Our data support the notion that tyrosine sulfation sites are often clustered and that sulfation of one site may depend on the negatively charged sulfates already present at other sites [34] . For example, the tyrosines of CCR5 at positions 3-15 are sulfated in a stepwise manner; tyrosines 14 and 15 are sulfated first, followed by tyrosines 10 and 3 [35] .…”

α-Conotoxin EpI, a Novel Sulfated Peptide from Conus episcopatusThat Selectively Targets Neuronal Nicotinic Acetylcholine Receptors

“…The known tyrosine-sulfated proteins can be classified into discrete functional classes including blood clotting factors, neuropeptides, extracellular matrix proteins, and immune system proteins (37). A recent revision of the consensus features for tyrosine O-sulfation based on mutational analysis experiments found, contrary to previous findings (i) that neighboring residues contribute only moderately to sulfation and (ii) that extensive sulfation can be obtained despite dramatic changes in the charge distribution of the neighboring residues, with basic residues not only being permissible near the site of sulfation but perhaps enhancing sulfation (39). The single critical position for tyrosine O-sulfation is Ϫ1, which should contain a neutral or acidic residue.…”

Monocyte Chemotactic Protein-1 Receptor CCR2B Is a Glycoprotein That Has Tyrosine Sulfation in a Conserved Extracellular N-Terminal Region

“…To test whether these residues are involved in the biological function of the receptor, site-directed mutagenesis was used. This mutagenesis involved the consensus sulfation site, including tyrosine, the suspected site of sulfation, and the neighboring amino acid residue that should be a part of the consensus required for enzymatic sulfation by protein tyrosine sulfotransferases (6,11). The results presented here demonstrate that the hexad is important for ligand binding, lamellipodium formation, chemotaxis, and signal transduction.…”

“…The sulfation of tyrosines occurs post-translationally, in the trans part of the Golgi network (6). The most important feature of tyrosine sulfation consensus sequences is the presence of an acidic or neutral amino acid residue directly before a tyrosine to be sulfated, although not all theoretical consensus sequences are sulfated in proteins (6,11). Several examples are known where sulfation of tyrosines was shown to be important either for protein-protein interaction (12)(13)(14)(15)(16) or for protein precursor processing (11).…”