dnaA

Chromosomal replication initiator protein dnaA

Identifiers
Symbol	dnaA
Entrez	948217
UniProt	P03004
Other data

Bac_DnaA_C

crystal structure of dnaa domainiv complexed with dnaabox dna
Identifiers
Symbol	Bac_DnaA_C
Pfam	PF08299
Pfam clan	CL0123
InterPro	IPR013159
SCOP	1j1v
SUPERFAMILY	1j1v
Available protein structures: Pfam structures PDB RCSB PDB; PDBe PDBsum structure summary

Bac_DnaA

structure of amppcp-bound dnaa from aquifex aeolicus
Identifiers
Symbol	Bac_DnaA
Pfam	PF00308
Pfam clan	CL0023
InterPro	IPR013317
PROSITE	PDOC00771
SCOP	1j1v
SUPERFAMILY	1j1v
Available protein structures: Pfam structures PDB RCSB PDB; PDBe PDBsum structure summary

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.

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. There are 8 dnaA binding sites within oriC, which dnaA binds with differential affinity. When DNA replication is about to commence, dnaA occupies all of the high and low affinity binding sites. 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

• MeSH DnaA+protein,+Bacteria

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 incorporates text from the public domain Pfam and InterPro IPR013159

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