Primer initiation and extension by T7 DNA primase

Udi Qimron, Seung Joo Lee, Samir M. Hamdan, Charles C. Richardson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


T7 DNA primase is composed of a catalytic RNA polymerase domain (RPD) and a zinc-binding domain (ZBD) connected by an unstructured linker. The two domains are required to initiate the synthesis of the diribonucleotide pppAC and its extension into a functional primer pppACCC (de novo synthesis), as well as for the extension of exogenous AC diribonucleotides into an ACCC primer (extension synthesis). To explore the mechanism underlying the RPD and ZBD interactions, we have changed the length of the linker between them. Wild-type T7 DNA primase is 10-fold superior in de novo synthesis compared to T7 DNA primase having a shorter linker. However, the primase having the shorter linker exhibits a two-fold enhancement in its extension synthesis. T7 DNA primase does not catalyze extension synthesis by a ZBD of one subunit acting on a RPD of an adjacent subunit (trans mode), whereas de novo synthesis is feasible in this mode. We propose a mechanism for primer initiation and extension based on these findings.

Original languageEnglish (US)
Pages (from-to)2199-2208
Number of pages10
Issue number10
StatePublished - May 17 2006
Externally publishedYes


  • DNA replication
  • Primer synthesis mechanism
  • RNA polymerase domain
  • Zinc-binding domain

ASJC Scopus subject areas

  • General Immunology and Microbiology
  • General Biochemistry, Genetics and Molecular Biology
  • Molecular Biology
  • General Neuroscience


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