US EPA

1352124 

Journal Article 

The arsR gene accounts for the antirestriction activity of transmission plasmid R64 (IncI1) 

Rastorguev, SM; Zavil'gel'skii, GB; Churikov, NA 

1998 

1 

Molecular Biology
ISSN: 0026-8933
EISSN: 1608-3245 

32 

2 

261-264 

WOS:000073566600013 

Transmission plasmid R64 (IncI1) alleviates the host controlled type I (EcoK) restriction of nonmodified phage lambda DNA in Escherichia coli K12
cells, i.e., expresses the Ard (alleviation of restriction of DNA) phenotype. Fragments of R64
were cloned in multicopy vectors, and the locus responsible for the Ard phenotype was located to
the distal part of the leader immediately adjacent to rep, about 60 kb apart from oriT. The 613-
nt EcoRI-PstI fragment of the locus was sequenced. A single 351-nt open reading frame was
detected that codes for a polypeptide of 117 amino acid residues. The polypeptide was identical
to ArsR, a transcriptional regulator of the ars operon (resistance to arsenite and arsenate) of
transmission plasmid R773 (IncFI). The major ars genes (arsABC) were assumed to be absent from
R64, because neither R64 nor hybrid pSR8 (containing the 9.2-kb EcoRI-D fragment with the arsR
gene) conferred arsenite resistance on E. coli K12. The arsR gene showed no homology to ardA and
ardB responsible for the synthesis of antirestriction proteins. However, a so-called
""antirestriction motif' of nine amino acid residues, characteristic of the Ard proteins, was
detected in ArsR. 

transmission plasmid; resistance factor; antirestriction; ard gene; ars gene; antirestriction motif