Interaction of DDSDEEN peptide with N-CAM protein. Possible mechanism enhancing neuronal differentiation.
DDSDEEN chromatin peptide, after dansylation, was studied for its ability to bind N-CAM protein. The binding causes a quenching of the Dns-peptide fluorescence emission. Dose- and time-dependent binding of Dns-peptide with N-CAM has been shown. Fluorescence quenching is completely lost if the Dns-peptide is subjected to carboxypeptidase digestion. Moreover the undansylated peptide pEDDSDEEN competes with the DnsDDSDEEN peptide for the binding with the N-CAM protein. The Dns-peptide-N-CAM bond has been related to the peptide biological activity probably involved in the promotion of neuronal differentiation. An attempt to recognize a possible N-CAM binding site for Dns-peptide was performed by alignment of N-CAM from various sources with some sequences that have been previously reported as binding sites for the pEDDSDEEN and DDSDEEN peptides. Interestingly, the alignment of N-CAM from various sources with the peptides WHPREGWAL and WFPRWAGQA recognizes on rat and human N-CAM a unique sequence that could be the specific binding site for chromatin peptide: WHSKWYDAK. This sequence is present in fibronectin type-III domain of N-CAM. In addition molecular modeling studies indicate the N-CAM sequence WHSKWYDAK as, probably, the main active site for DnsDDSDEEN (or pEDDSDEEN) peptide ligand. Accordingly the binding experiments show a high affinity between WHSKWYDAK and DnsDDSDEEN peptides.
Marsili
Valeria
V
Dipartimento di Biologia Cellulare e Ambientale, Università di Perugia, 06123 Perugia, Italy. vmarsili@unipg.it
Lupidi
Giulio
G
Berellini
Giuliano
G
Calzuola
Isabella
I
Perni
Stefano
S
Cruciani
Gabriele
G
Gianfranceschi
Gian Luigi
GL
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D043422:Carboxypeptidases A / Q000378:metabolism; D002454:Cell Differentiation; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019006:Neural Cell Adhesion Molecules / Q000737:chemistry / Q000378:metabolism*; D009474:Neurons / Q000502:physiology; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D020539:Sequence Analysis, Protein
D019006:Neural Cell Adhesion Molecules; D009842:Oligopeptides; C532437:aspartyl-aspartyl-seryl-aspartyl-glutamyl-glutamyl-asparagine; D043422:Carboxypeptidases A