The Ramachandran Principle is that alpha helices, beta strands, and

turns are the most likely conformations for a polypeptide chain to 

adopt, because most other conformations are impossible due to

steric collisions between atoms. 

TLS Online TPP Program

#Id: 5051

#Unit 3. Fundamental Processes

DnaA ATPase activity is stimulated by membrane phospholipids and single-stranded DNA.

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#Id: 5052

#Unit 3. Fundamental Processes

DnaA-ATP in an extended multimeric state promoted by the accessory protein DiaA, which stimulates cooperative binding of DnaA.

DnaA-ATP binds cooperatively to form a helical central core around which oriC DNA is wrapped.

TLS Online TPP Program

#Id: 5053

#Unit 3. Fundamental Processes

DnaA has a weak ATPase intrinsic activity which is enhanced by a factor termed Hda.

In a conceptually elegant feedback loop, Hda is recruited to a replication origin via the b subunit of the DNA polymerase. it acts to switch off DnaA

TLS Online TPP Program

#Id: 5054

#Unit 3. Fundamental Processes

Phospholipids promote the exchange of ATP with ADP bound to DnaA

TLS Online TPP Program

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#Unit 3. Fundamental Processes

DnaA then acts at three A-T–rich 13-bp tandem repeats located on the left side of oriC.

TLS Online TPP Program

#Id: 5056

#Unit 3. Fundamental Processes

Initiation of replication at oriC starts with formation of a complex that ultimately requires six proteins: DnaA, DnaB, DnaC, HU, gyrase, and SSB.