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Updated: Aug 9, 2026
Reconstitution of Nucleosomes with Differentially Isotope-labeled Sister Histones
Published on: March 26, 2017
Prothymosin alpha binds histones in vitro and shows activity in nucleosome assembly assay
C Díaz-Jullien1, A Pérez-Estévez, G Covelo
1Departamento de Bioquímica y Biología Molecular, Facultad de Biología, Universidad de Santiago, Spain.
Insights
Prothymosin alpha (Pro Talpha) binds to histones, particularly core histones H3 and H4. This binding facilitates in vitro nucleosome assembly, suggesting Pro Talpha
Area of Science:
- Molecular Biology
- Biochemistry
- Cell Biology
Background:
- Prothymosin alpha (Pro Talpha) is a polypeptide implicated in cell proliferation.
- Its exact biological function remains elusive.
- Understanding Pro Talpha's interactions is key to elucidating its role in cellular processes.
Purpose of the Study:
- To investigate the in vitro interactions between calf Prothymosin alpha (Pro Talpha) and histones.
- To characterize the binding affinity and specificity of Pro Talpha for different histone types.
- To explore the functional implications of Pro Talpha-histone interactions in nucleosome assembly.
Main Methods:
- Affinity chromatography using Pro Talpha-Sepharose columns.
- Immunoblotting assays to detect protein interactions.
- Analysis of Pro Talpha and histone mixtures in solution.
- In vitro nucleosome assembly assays.
Main Results:
- Calf Pro Talpha selectively binds to core histones (H3, H4, H2A, H2B) and histone H1.
- Pro Talpha exhibits higher affinity for core histones, especially H3 and H4.
- The acidic central region of Pro Talpha is largely responsible for histone binding, though the N-terminal region also contributes.
- Pro Talpha, with ATP and thymocyte extract factors, induced in vitro nucleosome assembly.
- Histone binding is not affected by Pro Talpha phosphorylation.
Conclusions:
- Prothymosin alpha (Pro Talpha) directly interacts with histones, influencing chromatin structure.
- Pro Talpha's ability to promote nucleosome assembly suggests a role in chromatin remodelling.
- Further research is warranted to fully define Pro Talpha's function in gene regulation and cell dynamics.
Abstract:
Prothymosin alpha (Pro Talpha) is a polypeptide which appears to be involved in cell proliferation, though its precise function has yet to be identified. Here, we report experiments which show that calf Pro Talpha selectively binds to core histones and histone H1 in vitro. Characterization of these interactions by various procedures (including affinity chromatography on Pro T alpha-Sepharose columns, immunoblotting assay and investigation of the behaviour of mixtures of Pro T alpha and histones in solution) indicated that Pro T alpha has higher affinity for core histones (particularly H3 and H4) than for H1. Similarities between the histone-binding patterns of Pro T alpha and of poly(glutamic acid) suggest that the observed histone-binding capacity resides largely in the acidic central region of Pro T alpha. However, all five histones were also bound by T alpha 1 (a peptide corresponding to the first 28 amino acids of Pro T alpha); histone binding by the N-terminal region of Pro T alpha thus cannot be ruled out. Phosphorylation of Pro T alpha does not appear to affect these interactions. In accordance with the observed capacity for histone binding, Pro T alpha (in conjunction with ATP and some Pro T alpha-binding factor/s in a thymocyte extract) was able to induce in vitro nucleosome assembly. We discuss the possibility that Pro T alpha plays a role in chromatin remodelling.
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