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Nucleoplasmin interaction with protamines. Involvement of the polyglutamic tract
Cèlia Prieto1, Núria Saperas, Carme Arnan
1Departament d'Enginyeria Química, ETSEIB, Universitat Politècnica de Catalunya, Diagonal 647, Barcelona E-08028, Spain.
Biochemistry
|June 12, 2002
Summary
Recombinant nucleoplasmin forms decondense sperm nuclei by removing protamines. The carboxyl-terminal polyglutamic tract enhances protamine removal efficiency but is not essential for sperm chromatin decondensation.
Area of Science:
- Molecular Biology
- Reproductive Biology
Background:
- Nucleoplasmin is a crucial protein involved in sperm chromatin remodeling.
- Understanding nucleoplasmin's structure-function relationship is key to its role in decondensation.
Purpose of the Study:
- To investigate the role of different recombinant nucleoplasmin forms in protamine removal and sperm chromatin decondensation.
- To determine the impact of carboxyl-terminal truncations on nucleoplasmin's function.
Main Methods:
- Expression and purification of recombinant nucleoplasmin variants (r-NP121, r-NP142).
- Analysis of oligomerization and hydrodynamic properties.
- Assessment of protamine binding stoichiometry and removal efficiency from sperm nuclei.
Main Results:
- Recombinant nucleoplasmin forms oligomerize into pentameric complexes.
- All forms decondense protamine-containing sperm nuclei.
- Protamine removal efficiency varies, with the main polyglutamic tract enhancing the process but not being indispensable.
Conclusions:
- The carboxyl-terminal polyglutamic tract of nucleoplasmin enhances protamine removal efficiency.
- Nucleoplasmin's ability to decondense sperm chromatin is retained even with partial truncation of this tract.