title: Probing the impact of valency on the routing of arginine-rich peptides into eukaryotic cells.
abstract: Multivalency represents a critical parameter in cell biology responsible for the overall avidity of low-affinity interactions and the triggering of cellular events. Functions such as catalytic activity, cellular uptake, or localization are frequently linked to the oligomeric state of a protein. This study explores the impact of multivalency on the import and routing of peptides into cells. Specifically, cationic import sequences such as decaarginine, decalysine, and the HIV Tat peptide (GRKKRRQRRRAP, residues 48-59) as well as the nuclear localization sequence from SV40 large T-antigen were assembled into defined peptide oligomers by fusing them to the tetramerization domain of human p53 (residues 325-355, hp53(tet) domain). The resulting tetravalent peptides typically displayed between 10- and 100-fold enhancements in cellular import and intracellular routing properties in relation to their monomeric homologues. These peptides were not toxic to cells. Flow cytometry results and transfection assays indicated that tetravalent decaarginyl peptides (10R-p53(tet) and NLS-10R-p53(tet)) were the peptides most efficiently routed into cells. Their mechanism of import was subsequently examined on unfixed, viable cells using a combination of metabolic inhibitors, flow cytometry, and microscopy techniques. These studies revealed that tetravalent arginine-rich peptides bind to heparan sulfate on the cell surface, are internalized at 37 degrees C, but not at 4 degrees C, via a clathrin-mediated pathway, and accumulate into endosome-like acidic compartments. A fraction of these tetravalent peptides access the cytosol and accumulate in the nucleus of cells. This study concludes that the oligomerization of proteins harboring arginine-rich peptide chains may profoundly influence their ability to enter and be routed into cells.
authors.affiliation: Department of Medical Biophysics, University of Toronto, and Ontario Cancer Institute, University Health Network, Toronto, Ontario, Canada.
authors.forename: Kim S
authors.initials: KS
authors.lastname: Kawamura
authors.forename: Michael
authors.initials: M
authors.lastname: Sung
authors.forename: Eleonora
authors.initials: E
authors.lastname: Bolewska-Pedyczak
authors.forename: Jean
authors.initials: J
authors.lastname: Gariépy
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001120:Arginine / Q000737:chemistry* / Q000378:metabolism*; D016466:CHO Cells; D002522:Chlorocebus aethiops; D002966:Clathrin / Q000378:metabolism; D006224:Cricetinae; D004705:Endocytosis; D006497:Heparan Sulfate / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D018613:Microscopy, Confocal; D008954:Models, Biological; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D017354:Point Mutation; D017434:Protein Structure, Tertiary / Q000235:genetics; D021381:Protein Transport / Q000502:physiology; D013997:Time Factors; D014162:Transfection; D022161:Transport Vesicles / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D014709:Vero Cells
chemical_list: D001120:Arginine; D002966:Clathrin; D006497:Heparan Sulfate; D010446:Peptide Fragments; D010455:Peptides; D016159:Tumor Suppressor Protein p53; C509416:p53 protein (325-355), decaarginyl-; C509415:p53 protein (325-355), human