Nucleotide sequence of the gene (ard) encoding the antirestriction protein of plasmid colIb-P9.

AUTOR(ES)

Delver, E P

RESUMO

The IncI1 plasmid ColIb-P9 was found to encode an antirestriction function. The relevant gene, ard (alleviation of restriction of DNA), maps about 5 kb from the origin of transfer, in the region transferred early during bacterial conjugation. Ard inhibits both restriction and modification by each of the four type I systems of Escherichia coli tested, but it had no effect on restriction by either EcoRI, a type II system, or EcoP1, a type III system. The nucleotide sequence of the ColIb ard gene was determined; the predicted molecular weight of the Ard polypeptide is 19,193. The proposed polypeptide chain contains an excess of 25 negatively charged amino acids, suggesting that its overall character is very acidic. Deletion analysis of the gene revealed that the Ard protein contained a distinct functional domain located in the COOH-terminal half of the polypeptide. We suggest that the biological role of the ColIb Ard protein is associated with overcoming host-controlled restriction during bacterial conjugation.

Documentos Relacionados

• The ssb gene of plasmid ColIb-P9.
• Organization of the replication control region of plasmid ColIb-P9.
• Direction of conjugative transfer of IncI1 plasmid ColIb-P9.
• Structural and functional features of cis-acting sequences in the basic replicon of plasmid ColIb-P9.
• Transfer of tra proteins into the recipient cell during bacterial conjugation mediated by plasmid ColIb-P9.