The domain structure and the function of poly(ADP-ribose) synthetase

Area of Science:

• Molecular Biology
• Biochemistry
• Genetics

Background:

• Poly(ADP-ribose) synthetase is a chromatin-bound enzyme utilizing NAD.
• This enzyme requires DNA for its catalytic activity.
• It is abundant in rapidly proliferating normal tissues and malignant tumor cells.

Purpose of the Study:

• To investigate the structure and function of poly(ADP-ribose) synthetase.
• To understand its role in gene expression regulation.

Main Methods:

• Purification of the enzyme from calf thymus, mouse testis, and human placenta.
• Analysis of amino acid composition and antigenic structures using antibodies.
• Proteolytic digestion to identify functional domains.
• Assay of DNA binding and enzymatic activity in cell lysates.

Main Results:

• The enzyme's amino acid composition and antigenic structures are highly conserved across species.
• Proteolytic digestion revealed distinct DNA-binding, automodification, and NAD-binding domains.
• The DNA-binding domain suppresses nick-induced transcription initiation.
• The enzyme poly(ADP-ribosyl)ates RNA polymerase and other nuclear enzymes.

Conclusions:

• Poly(ADP-ribose) synthetase plays a critical role in regulating gene expression in eukaryotic cells.
• Its conserved structure and functional domains highlight its importance in cellular processes.