Surface-exposed amino acids of eosinophil cationic protein play a critical role in the inhibition of mammalian cell proliferation.
Eosinophil cationic protein (ECP) is a ribonuclease secreted from activated eosinophils that may cause tissue injure as a result of eosinophilic inflammation. ECP possesses bactericidal, antiviral and helminthotoxic activity and inhibits mammalian cell growth. The mechanism by which ECP exerts its toxicity is not known but it has been related to the ability of the protein to destabilise lipid bilayers. We have assessed the involvement of some cationic and aromatic surface exposed residues of ECP in the inhibition of proliferation of mammalian cell lines. We have constructed ECP mutants for the selected residues and assessed their ability to prevent cell growth. Trp10 and Trp35 together with the adjacent stacking residue are critical for the damaging effect of ECP on mammalian cell lines. These residues are also crucial for the membrane disruption activity of ECP. Other exposed aromatic residues packed against arginines (Arg75-Phe76 and Arg121-Tyr122) and specific cationic amino acids (Arg101 and Arg104) of ECP play a secondary role in the cell growth inhibition. This may be related to the ability of the protein to bind carbohydrates such as those found on the surface of mammalian cells.
Carreras
Esther
E
Departament de Bioquímica i Biologia Molecular, Facultat de Ciències, Universitat Autònoma de Barcelona, 08193-Bellaterra, Spain.
Boix
Ester
E
Navarro
Susanna
S
Rosenberg
Helene F
HF
Cuchillo
Claudi M
CM
Nogués
M Victòria
MV
D019943:Amino Acid Substitution; D024322:Amino Acids, Aromatic / Q000737:chemistry / Q000235:genetics; D049109:Cell Proliferation / Q000187:drug effects*; D047150:Eosinophil Cationic Protein / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology*; D006801:Humans; D009154:Mutation; D011487:Protein Conformation; D014364:Tryptophan / Q000737:chemistry / Q000235:genetics; D014407:Tumor Cells, Cultured
D024322:Amino Acids, Aromatic; D014364:Tryptophan; D047150:Eosinophil Cationic Protein