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IncI1 plasmid R64 encodes the ArsR protein that alleviates type I restriction
Author(s) -
Rastorguev Sergei M,
Zavilgelsky Gennadii B,
Tchurikov Nickolai A
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)00285-3
Subject(s) - plasmid , biology , gene , genetics , operon , microbiology and biotechnology , open reading frame , restriction enzyme , bamhi , ecori , restriction map , nucleic acid sequence , escherichia coli , peptide sequence
The host‐controlled Eco K restriction of unmodified phage λ was five‐fold alleviated in the wild‐type Escherichia coli strain K12 carrying the R64 plasmid of the incompatibility group I1. The relevant gene was mapped between the origin of vegetative replication ( rep , ori V) and the tet r gene about 60 kbp downstream from the origin of transfer, ori T. We cloned this gene inside the 613 bp long Eco RI‐ Pst I fragment and sequenced it. Only one 351 bp long open reading frame (ORF) starting at 124 bp from the beginning of the insert was found in the sequence. Computer search in the current databases revealed that the putative protein is identical to the ArsR protein specified by the IncFI plasmid R773. ArsR is a repressor of the arsenical resistance ( ars ) operon, ars RDABC. There are no ars ABC genes in the R64 plasmid since plasmid R64‐ (or pSR8)‐mediated resistance of E. coli K12 cells to the arsenicals arsenate and arsenite was not detected. The gene ars R and the antirestriction genes ard ( ard A and ard B) are non‐homologous. However, comparison of the deduced amino acid sequence of ArsR with the ArdA and ArdB sequences revealed only one small region of similarity, a 9 amino acid motif found in different antirestriction proteins that is hypothesized to be an interaction site for antirestriction proteins with restriction endonucleases.