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NBP-45, a novel nucleosomal binding protein with a tissue-specific and developmentally regulated expression.
H Shirakawa1, D Landsman, Y V Postnikov
1Institute of Computational Biology Branch, National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland 20892, USA.
The Journal of Biological Chemistry
|February 29, 2000
Summary
Researchers identified a new nuclear protein, NBP-45, which binds to nucleosomes and activates transcription. This protein, crucial for early embryonic development, shares functional domains with HMG-14/-17 proteins.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- High mobility group (HMG) proteins 14/17 are ubiquitous nuclear proteins involved in chromatin structure.
- Understanding novel proteins interacting with chromatin is essential for deciphering gene regulation.
Purpose of the Study:
- To characterize a novel murine nuclear protein, NBP-45, and elucidate its functional domains and role in gene expression.
- To investigate the structural and functional relationship of NBP-45 to the HMG-14/-17 protein family.
Main Methods:
- Protein characterization through sequence analysis and domain identification.
- mRNA expression analysis in various mouse tissues and embryonic stages.
- Functional domain mapping for nuclear localization, nucleosome binding, and transcriptional activation.
Main Results:
- NBP-45, a 406-amino acid protein, shares homologous domains (nuclear localization, nucleosome binding, chromatin unfolding) with HMG-14/-17.
- NBP-45 mRNA is expressed in all tested mouse tissues, with highest abundance in 7-day-old embryos.
- The N-terminal region mediates nuclear entry and nucleosome binding, while the C-terminal domain activates transcription.
Conclusions:
- NBP-45 is a novel nucleosome-binding protein with transcriptional activator functions, suggesting a role in early embryonic development.
- The study identifies a nucleosomal binding domain motif present in proteins beyond the HMG-14/-17 family.
- NBP-45 binding to nucleosomes creates a region of high local negative charge, influencing chromatin structure and gene regulation.