by Jessica Marcellus
Bacteriophage T7 is a lytic phage that uses E. coli as a host to replicate its DNA. Its
linear chromosome is replicated by a DNA replication complex working in concert with helicase,
primase, and single strand binding proteins. The replication complex is a member of the PolI
family of polymerases. It contains two active sites: a 5'-3' polymerase site for addition of
deoxyribonucleotides and a 3'-5' exonuclease site for proofreading. The T7 polymerase does not
exhibit 5'-3' exonuclease activity.
CLICK HERE TO SEE A SCHEMATIC OF THE REPLICATION FORK
Enzyme Structure and DNA Binding:
The general shape of the T7 replication complex and other members of the PolI
family is described as a right hand, with regions corresponding to fingers ,
a palm, and a thumb .