Nucleoplasmin interaction with protamines. Involvement of the polyglutamic tract.
Different recombinant forms of nucleoplasmin including truncations at the carboxyl-terminal end of the molecule (r-NP121, r-NP142) have been expressed and purified. All of them were found to oligomerize, forming pentameric complexes which, according to their hydrodynamic properties, can be modeled by oblate ellipsoids of constant width. In this model, the highly charged carboxyl ends appear to be arranged around a pentameric core along the plane defined by the major axes of the ellipsoid. Importantly, all the recombinant forms appear to be able to decondense protamine-containing sperm nuclei. However, although the stoichiometry with which protamines bind to these forms appears to be constant (2.5 mol of protamine/mol of nucleoplasmin pentamer), the efficiency with which they remove protamines from the sperm DNA decreases in the following order: o-NP > r-NP142 > or = r-NP >> r-NP121. Therefore, the main polyglutamic tract of nucleoplasmin (which is absent in r-NP121), while enhancing the efficiency of protamine removal, is not indispensable for sperm chromatin decondensation in the biological model we have used.
Prieto
Cèlia
C
Departament d'Enginyeria Química, ETSEIB, Universitat Politècnica de Catalunya, Diagonal 647, Barcelona E-08028, Spain.
Saperas
Núria
N
Arnan
Carme
C
Hills
Melissa H
MH
Wang
Xiaoying
X
Chiva
Manel
M
Aligué
Rosa
R
Subirana
Juan A
JA
Ausió
Juan
J
D000595:Amino Acid Sequence; D000818:Animals; D001492:Bass; D002025:Bufonidae; D002467:Cell Nucleus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D056489:Nucleoplasmins; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011099:Polyglutamic Acid / Q000737:chemistry* / Q000502:physiology*; D011479:Protamines / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding / Q000235:genetics; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D017384:Sequence Deletion; D013050:Spectrometry, Fluorescence; D013094:Spermatozoa / Q000737:chemistry / Q000378:metabolism; D014982:Xenopus laevis / Q000235:genetics
D009687:Nuclear Proteins; D056489:Nucleoplasmins; D010750:Phosphoproteins; D011479:Protamines; D011994:Recombinant Proteins; D011099:Polyglutamic Acid