The process catalyzed by the bacteriophage λ integrase

[hidemi]

Homework Statement:

Which statement is TRUE regarding the process catalyzed by the bacteriophage λ integrase?

A) Serines in the protein active site become covalently attached to the nucleic acids during the mechanism.
B) The reaction is an ATP-dependent process.
C) The reaction steps are successive tranesterifications.
D) The integrase can be classified as a hydrolase.
E) The target DNA sequence for this protein is nonspecific.

The answer is C.

Relevant Equations:

NONE

Why are the steps catalyzed by the bacteriophage λ integrase successive tranesterifications?
How are (A), (B) ,(D) wrong?