Send to

Choose Destination
Cell. 1989 Nov 17;59(4):667-74.

The replication terminator protein of E. coli is a DNA sequence-specific contra-helicase.

Author information

Department of Microbiology and Immunology, Duke University Medical Center, Durham, North Carolina 27710.


We have cloned the tus gene that encodes the replication terminator protein of Escherichia coli and have efficiently expressed its gene product. The overproducer strain has been used to purify the terminator (ter) protein in high yield to near homogeneity. The protein is a single 36 kd polypeptide. Using the ter protein and highly purified dnaB helicase, we show that the terminator protein is a DNA sequence-specific contra-helicase, i.e., the protein when bound to its recognition sequence (tau) strongly impedes the ATP-dependent unwinding of double-stranded DNA. This contra-helicase activity is polar, i.e., the impedance to unwinding takes place in only one orientation of the tau sequence. The results illuminate the mechanism of replication termination specifically at tau.

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center