title: Structural and energetic determinants of tyrosylprotein sulfotransferase sulfation specificity.
abstract: BACKGROUND
  Tyrosine sulfation is a type of post-translational modification (PTM) catalyzed by tyrosylprotein sulfotransferases (TPST). The modification plays a crucial role in mediating protein-protein interactions in many biologically important processes. There is no well-defined sequence motif for TPST sulfation, and the underlying determinants of TPST sulfation specificity remains elusive. Here, we perform molecular modeling to uncover the structural and energetic determinants of TPST sulfation specificity.
  
  
  RESULTS
  We estimate the binding affinities between TPST and peptides around tyrosines of both sulfated and non-sulfated proteins to differentiate them. We find that better differentiation is achieved after including energy costs associated with local unfolding of the tyrosine-containing peptide in a host protein, which depends on both the peptide's secondary structures and solvent accessibility. Local unfolding renders buried peptide-with ordered structures-thermodynamically available for TPST binding. Our results suggest that both thermodynamic availability of the peptide and its binding affinity to the enzyme are important for TPST sulfation specificity, and their interplay results into great variations in sequences and structures of sulfated peptides. We expect our method to be useful in predicting potential sulfation sites and transferable to other TPST variants. Our study may also shed light on other PTM systems without well-defined sequence and structural specificities.
  
  
  METHODS
  All the data and scripts used in the work are available at http://dlab.clemson.edu/research/Sulfation.
authors.affiliation: Department of Physics and Astronomy and Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC 29634, USA.
authors.forename: Praveen
authors.initials: P
authors.lastname: Nedumpully-Govindan
authors.affiliation: Department of Physics and Astronomy and Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC 29634, USA.
authors.forename: Lin
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Physics and Astronomy and Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC 29634, USA.
authors.forename: Emil G
authors.initials: EG
authors.lastname: Alexov
authors.affiliation: Department of Physics and Astronomy and Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC 29634, USA.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Blenner
authors.affiliation: Department of Physics and Astronomy and Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC 29634, USA.
authors.forename: Feng
authors.initials: F
authors.lastname: Ding
mesh_terms: D015483:HIV Antibodies / Q000737:chemistry / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D058767:Protein Unfolding; D055672:Static Electricity; D015238:Sulfotransferases / Q000737:chemistry* / Q000378:metabolism; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D015483:HIV Antibodies; D008565:Membrane Proteins; D010455:Peptides; C005662:tyrosine O-sulfate; D014443:Tyrosine; D015238:Sulfotransferases; C114740:TPST2 protein, human; C039079:protein-tyrosine sulfotransferase