An N-terminal fragment of the gene 4 helicase/primase of bacteriophage T7 retains primase activity in the absence of helicase activity.

Content Provider	Semantic Scholar
Author	Frick, David N. Baradaran, Khandan Richardson, Charles.
Copyright Year	1998
Abstract	Primase and helicase activities of bacteriophage T7 are present in a single polypeptide coded by gene 4. Because the amino terminal region of the gene 4 protein contributes to primase activity, we constructed a truncated gene 4 encoding the N-terminal 271-aa residues. The truncated protein, purified from cells overexpressing the protein, is a dimer in solution; the full-length protein is a hexamer. Although the fragment is devoid of dTTPase and helicase activities, it catalyzes template-directed synthesis of di-, tri-, and tetranucleotides. The rates for tetraribonucleotide synthesis and for dinucleotide extension on a 20-nucleotide template are similar for the full-length and truncated proteins. However, the activity of the primase fragment is unaffected by dTTP whereas the primase activity of the full-length protein is stimulated >14-fold. The primase fragment is defective in the interaction with T7 DNA polymerase in that primer synthesis cannot be coupled to DNA synthesis.
File Format	PDF HTM / HTML
DOI	10.1073/pnas.95.14.7957
PubMed reference number	9653122
Journal	Medline
Volume Number	95
Issue Number	14
Alternate Webpage(s)	http://www.pnas.org/content/95/14/7957.full.pdf
Alternate Webpage(s)	https://people.uwm.edu/frickd/files/2016/05/13_Frick-et-al-1998-20d7zr2.pdf
Journal	Proceedings of the National Academy of Sciences of the United States of America
Language	English
Access Restriction	Open
Content Type	Text
Resource Type	Article