Which option is correct for T4 DNA ligase?

Correct answer: It uses ATP to join DNA ends

T4 DNA ligase joins broken DNA ends by forming phosphodiester bonds, and it uses ATP for this reaction. DNA ligase that uses NAD+ is typically found in bacteria such as E. coli. Cutting DNA at recognition sequences is done by restriction endonucleases, whereas adding new nucleotides is the role of DNA polymerase. Exam tip: Remember T4 DNA ligase as an ATP-dependent ligase.