Phylogenetic and functional analysis of histidine residues essential for pH-dependent multimerization of von Willebrand factor.
J Biol Chem, 2011/7/22;286(29):25763-9.
Dang LT[1], Purvis AR, Huang RH, Westfield LA, Sadler JE
Affiliations
PMID: 21592973DOI: 10.1074/jbc.M111.249151
Impact factor: 5.486
Abstract
von Willebrand factor (VWF) is a multimeric plasma protein that mediates platelet adhesion to sites of vascular injury. The hemostatic function of VWF depends upon the formation of disulfide-linked multimers, which requires the VWF propeptide (D1D2 domains) and adjacent D'D3 domains. VWF multimer assembly occurs in the trans-Golgi at pH ~ 6.2 but not at pH 7.4, which suggests that protonation of one or more His residues (pK(a) ~6.0) mediates the pH dependence of multimerization. Alignment of 30 vertebrate VWF sequences identified 13 highly conserved His residues in the D1D2D'D3 domains, and His-to-Ala mutagenesis identified His³⁹⁵ and His⁴⁶⁰ in the D2 domain as critical for VWF multimerization. Replacement of His³⁹⁵ with Lys or Arg prevented multimer assembly, suggesting that reversible protonation of this His residue is essential. In contrast, replacement of His⁴⁶⁰ with Lys or Arg preserved normal multimer assembly, whereas Leu, Met, and Gln did not, indicating that the function of His⁴⁶⁰ depends primarily upon the presence of a positive charge. These results suggest that pH sensing by evolutionarily conserved His residues facilitates the assembly and packaging of VWF multimers upon arrival in the trans-Golgi.
MeSH terms
Animals; Cell Line; Conserved Sequence; Histidine; Humans; Hydrogen-Ion Concentration; Molecular Sequence Data; Mucins; Mutagenesis; Phylogeny; Protein Multimerization; Protein Structure, Quaternary; Sequence Homology, Amino Acid; trans-Golgi Network; von Willebrand Factor
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