dnaA

Chromosomal replication initiator protein dnaA
Identifiers
Symbol dnaA
Entrez 948217
UniProt P03004
Other data
Bac_DnaA_C
PDB 1j1v EBI.jpg
crystal structure of dnaa domainiv complexed with dnaabox dna
Identifiers
Symbol Bac_DnaA_C
Pfam PF08299
Pfam clan CL0123
InterPro IPR013159
SCOP 1j1v
Bac_DnaA
PDB 2hcb EBI.jpg
structure of amppcp-bound dnaa from aquifex aeolicus
Identifiers
Symbol Bac_DnaA
Pfam PF00308
Pfam clan CL0023
InterPro IPR013317
PROSITE PDOC00771
SCOP 1j1v

dnaA is a replication initiation factor which promotes the unwinding or denaturation of DNA at oriC (around 240bp in Escherichia coli), during DNA replication in prokaryotes.

The formation of the oriC/DnaA complex and DNA unwinding requires ATP hydrolysis[1].

The oriC site in E. coli has three AT rich 13 base pair regions (DUE's elements) followed by five 9 bp regions. Around 10 dnaA molecules bind to the 9 bp regions, which wrap around the proteins causing the DNA at the AT-rich region to unwind. The denatured AT-rich region allows for the recruitment of DnaB (helicase) complexes with DnaC (helicase loader). DnaC helps the helicase to bind to and to properly accommodate the ssDNA at the 13 bp region, this is accomplished by ATP hydrolysis after which DnaC is released. Single-strand binding protein's (SSBs) stabilize the single DNA strands in order to maintain the replication bubble. DnaB is a 5'->3' helicase, so it travels on the lagging strand. It associates with DnaG (a primase) to form the only primer for the leading strand and to add RNA primers on the lagging strand. The interaction between DnaG and DnaB is necessary to control the longitude of Okazaki fragments on the lagging strand. DNA polymerase III is then able to start DNA replication.

DnaA contains two conserved regions: the first is located in the central part of the protein and corresponds to the ATP-binding domain, the second is located in the C-terminal half and could be involved in DNA-binding.

External links

References

  • Voet, Donald; Voet, Judith; Pratt, Charlotte (2001). Fundamentals of Biochemistry. Wiley.
  • Nelson, David L.; Cox, Michael M. (2008). "Principles of Biochemistry". Freeman.

This article includes text from the public domain Pfam and InterPro IPR013159

This article includes text from the public domain Pfam and InterPro IPR013317


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