Open AccessThe replication initiator protein of plasmid pT181 has sequence-specific endonuclease and topoisomerase-like activities.
Author(s) -
Richard R. Koepsel,
Robert W. Murray,
Warren D. Rosenblum,
Saleem A. Khan
Publication year - 1985
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.82.20.6845
Subject(s) - rolling circle replication , plasmid , biology , dna , dna replication , restriction enzyme , microbiology and biotechnology , endonuclease , sequence (biology) , nucleotide , origin of replication , biochemistry , gene
Initiation of pT181 DNA replication specifically requires the plasmid-encoded RepC protein. Here we demonstrate that highly purified RepC protein has sequence-specific endonuclease and topoisomerase-like activities. A maximum sequence of 127 base pairs containing the pT181 origin of replication is required for nicking-closing by RepC protein. RepC introduces a single strand break within the pT181 origin. The nick site has been shown by DNA sequencing to lie between nucleotides 70 and 71 in the bottom strand of the DNA within the origin sequence. This nick site probably corresponds to the start site of pT181 replication. The results presented here suggest that, unlike most other plasmids, pT181 replicates by a rolling circle mechanism.