Glycosaminoglycan promoted cell entry of cell-penetrating peptide GBPECP depends on a single Tryptophan

• Main Authors: Hung, Li Chun, 洪莉鈞
• Other Authors: Sue, Shih Che
• Format: Others
• Language: en_US
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/49310558774612784088

碩士 === 國立清華大學 === 生物資訊與結構生物研究所 === 104 === A 10-residue glycosaminoglycan binding peptide derived from human eosinophil cationic protein, GBPECP, has been recently designated as a potent cell-penetrating peptide. Intracellular penetration of GBPECP highly depends on the existence of a tryptophan residue in the sequence. To realize the cell-penetrating mechanism in a model system mimicking peptide, glycan, and membrane environment, Dodecylphosphocholine (DPC) lipid micelle and heparin fragment were titrated into GBPECP solution to induce chemical shift perturbations in nuclear magnetic resonance (NMR) study. Our data showed that charged residues of R5 and K7 played substantial roles in recognizing heparin while R3 had less effect. The only aromatic residue W4, however, acted as an irreplaceable moiety for lipid membrane insertion, suggesting its critical role in related to GBPECP cell entry. Interestingly, although replacement of W4 with R4 significantly improved heparin binding activity of the peptide, such modification abolished cell penetration. Furthermore, in the absence of heparin, binding between GBPECP and DPC micelle still took place. The side chain of W4 adopts an opposite orientation from those of R5 and R7, with W4 responsible for cell penetrating and both R5 and K7 for GAG binding. These two effects appeared to synergistically promote GBPECP penetration through macropinocytosis and further modulate microenvironment of cell surface. More recently we have discovered that GBPECP treatment suppressed tumor cell migration and invasion. GBPECP, therefore, shows high potential as novel therapeutics through rapid and effective internalization, and interference with cell motility.