title: Electrostatic interactions at the C-terminal domain of nucleoplasmin modulate its chromatin decondensation activity.
abstract: The chromatin decondensation activity, thermal stability, and secondary structure of recombinant nucleoplasmin, of two deletion mutants, and of the protein isolated from Xenopus oocytes have been characterized. As previously reported, the chromatin decondensation activity of recombinant, unphosphorylated nucleoplasmin is almost negligible. Our data show that deletion of 50 residues at the C-terminal domain of the protein, containing the positively charged nuclear localization sequence, activates its chromatin decondensation ability and decreases its stability. Interestingly, both the decondensation activity and thermal stability of this deletion mutant resemble those of the phosphorylated protein isolated from Xenopus oocytes. Deletion of 80 residues at the C-terminal domain, containing the above-mentioned positively charged region and a poly(Glu) tract, inactivates the protein and increases its thermal stability. These findings, along with the effect of salt on the thermal stability of these proteins, suggest that electrostatic interactions between the positive nuclear localization sequence and the poly(Glu) tract, at the C-terminal domain, modulate protein activity and stability.
authors: Unidad de Biofísica (CSIC-UPV/EHU) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, Aptdo. 644, 48080 Bilbao, Spain.
authors: Aitor
authors: A
authors: Hierro
authors: Jesús M
authors: JM
authors: Arizmendi
authors: Sonia
authors: S
authors: Bañuelos
authors: Adelina
authors: A
authors: Prado
authors: Arturo
authors: A
authors: Muga
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002152:Calorimetry, Differential Scanning; D002467:Cell Nucleus / Q000737:chemistry / Q000378:metabolism; D002843:Chromatin / Q000737:chemistry / Q000378:metabolism*; D002942:Circular Dichroism; D005260:Female; D008297:Male; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D056489:Nucleoplasmins; D010446:Peptide Fragments / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D010750:Phosphoproteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D017434:Protein Structure, Tertiary / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000494:pharmacology; D013094:Spermatozoa / Q000737:chemistry / Q000378:metabolism; D055672:Static Electricity; D014982:Xenopus laevis
chemical_list: D002843:Chromatin; D009687:Nuclear Proteins; D056489:Nucleoplasmins; D010446:Peptide Fragments; D010750:Phosphoproteins; D011994:Recombinant Proteins