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DNA primase | |
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Identifiers | |
Organism | |
Symbol | dnaG |
Alt. symbols | dnaP |
Entrez | 947570 |
RefSeq (Prot) | NP_417538 |
UniProt | P0ABS5 |
Other data | |
EC number | 2.7.7.7 |
Chromosome | chromosome: 3.21 - 3.21 Mb |
DnaG is a bacterial primase which synthesizes short RNA oligonucleotides during DNA replication. These RNA oligonucleotides serve as primers for DNA synthesis by bacterial DNA polymerase Pol III. On one of the two parental strands, called the lagging strand, the primase makes a primer every few kilobases. These primers serve a substrates for synthesis of Okazaki fragments.
DnaG associates through noncovalent interactions with bacterial replicative helicase DnaB to perform its primase activity, with about three DnaG primase proteins associating with each DnaB helicase. Primases tend to initiate synthesis at specific three nucleotide sequences on single-stranded DNA (ssDNA) strand templates, and for DnaG the sequence is GTA.
The DnaG primase is a 581 residue monomeric protein with three functional domains, according to proteolysis studies. There is an N-terminal Zn++ binding domain (residues 1-110) where a zinc ion is tetrahedrally coordinated between one histidine and three cysteine residues, which may play a role in recognizing ssDNA. The central domain (residues 111-433) displays RNA polymerase activities, and is the site of RNA primer synthesis. The C-terminal domain (residues 434-581) is responsible for the noncovalent binding of DnaG to the DnaB helicase protein.[1]
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