A uniformly labelled (32P) single-stranded DNA (ssDNA) was incubated with a homologous double-stranded DNA (dsDNA) in the presence of Rad51 and/or RPA along with ATP or the non-hydrolysable ATPγS to study a three-strand exchange reaction. The reactions were terminated at various time points, DNA were digested with EcoRI followed by electrophoresis and autoradiography. Results are shown in the figure below.
Based on the above data, which one of the following statements is INCORRECT?
1
Rad51 requires ATP hydrolysis for strand exchange reaction.
2
Strand exchange does not take place in the absence of RPA.
3
The polarity of strand-exchange reaction is in the 3 ́ to 5 ́ direction.
4
The rate of strand-exchange is 7 kb/hour.