A ColE1-type plasmid from Salmonella enteritidis encodes a DNA cytosine methyltransferase.
The multicopy plasmid pFM366 was isolated from a virulent Salmonella enteritidis strain and was found to code for DNA methylase activity (Ibáñez and Rotger, 1993). The present work was aimed at characterizing the genetic organization and functional features of this 5.6 kb plasmid. We found pFM366 almost identical to the plasmid P4 isolated from Shigella sonnei, that encodes the SsoII restriction-modification system (Karyagina et al., 1993), and related to other ColE1-type plasmids. Examination of these plasmids revealed a common organization which suggests they were the result of similar recombinational events. The cytosine methylase of pFM366 is nearly identical to M. SsoII, whereas the gene encoding the restrictase homologous to R. SsoII is truncated and its product is inactive. The expression of the cytosine methylase encoded by pFM366 is strongly affected by deletion of regions located upstream and downstream of its ORF, and is negatively controlled by the rpoS gene in Escherichia coli. The methylase activity encoded by pFM366 induces the SOS response, which could be responsible for the observed delay in the growth of E. coli.
Ibáñez
M
M
Departamento de Microbiologia II, Facultad de Farmacia, Universidad Complutense, Madrid, Spain.
Alvarez
I
I
Rodríguez-Peña
J M
JM
Rotger
R
R
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics*; D004254:DNA Nucleotidyltransferases / Q000235:genetics / Q000378:metabolism; D015257:DNA-Cytosine Methylases / Q000235:genetics / Q000378:metabolism; D015252:Deoxyribonucleases, Type II Site-Specific / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development; D015964:Gene Expression Regulation, Bacterial; D019426:Integrases; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010957:Plasmids / Q000235:genetics* / Q000378:metabolism; D045522:Recombinases; D018741:Replication Origin; D015183:Restriction Mapping; D012477:Salmonella enteritidis / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; C042833:ROM protein, Bacteria; D045522:Recombinases; D012808:Sigma Factor; C069567:sigma factor KatF protein, Bacteria; C063974:DNA modification methylase SsoII; D015257:DNA-Cytosine Methylases; D004248:DNA (Cytosine-5-)-Methyltransferases; D004254:DNA Nucleotidyltransferases; D019426:Integrases; C115006:integron integrase IntI1; C045297:CCNGG-specific type II deoxyribonucleases; D015252:Deoxyribonucleases, Type II Site-Specific