DNA Flashcards
DnaB
helicase, ATP-dependent unwinding of DNA
DnaG
primase (RNA polymerase) synthesizes primers
TopA
topoisomerase, detangles DNA
PolA
DNA polymerase 1. replaces RNA primers
LigA
ligates 3’OH of strand with 5’P of okazaki fragments
DARS1 (site in the genome)
DnaA activation
DARS2 (site in the genome)
reactivation of DnaA. free ATP bind to DnaA and now DnaA has high affinity for the nucleotide binding site.
-Fis and IHF bind to DARS2 in order to facilitate and activate this exchange of ADP to ATP.
factors involved in replication initiation
HU, IHF, Fis
HU
nucleoid associated protein that helps destabilize double-stranded DNA at the origin.
IHF
integration host factor, bends DNA
Fis
factor for inversion stimulation. helps stabilize initial initiation complex.
where does DnaA bind in the OriC?
between the duplex unwinding element and the IHF binding site
SeqA-oriC regulates?
prevents binding of DnaA at the oriC. SeqA fxns when hemimethylated DNA is present. methylation occurs on the A of GATC motifs in the DNA.
ATP-DnaA regulates?
prevents dnaA gene transcription
steps for initiation
- DnaA is activated with ATP
- DnaA binds to DnaA binding box (between DUE and IBS) - DnaA oligomerizes
- DnaB is recruited
- DnaG is recruited
- DnaA is inactived and dissociates, priming by DnaG
- DNA polymerase III holoenzyme will bind and replication starts.