title: A plasmid-encoded DsbA homologue is a growth-phase regulated thioredoxin.
abstract: The Pseudomonas aeruginosa plasmid pUM505 contains in a pathogenicity island the dsbA2 gene, which encodes a product with similarity to DsbA protein disulfide isomerases, enzymes that catalyze formation and isomerization of disulfide bonds in protein cysteine residues. Using transcriptional fusions, it was found that dsbA2 gene promoter is activated during the stationary phase, suggesting that DsbA2 protein may be required for adaptive changes that occur during this stage of bacterial growth. Transfer of the pUM505 dsbA2 gene to a cadmium-sensitive P. aeruginosa PAO1-derivative affected in the chromosomal dsbA gene, restored cadmium resistance, suggesting a role of DsbA2 in protecting protein disulfide bonds. PAO1 dsbA2 transformants displayed increased sensitivity to intercalating agent mitomycin C, indicating that DsbA2 functions as a thioredoxin enzyme able to modify and activate toxicity of this compound. These results highlight the adaptive role of the pUM505 plasmid in its P. aeruginosa hosts.
authors.affiliation: Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana, Morelia, Michoacán, Mexico.
authors.forename: Amada
authors.initials: A
authors.lastname: Díaz-Magaña
authors.affiliation: Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana, Morelia, Michoacán, Mexico.
authors.forename: Martha P
authors.initials: MP
authors.lastname: Chávez-Moctezuma
authors.affiliation: Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana, Morelia, Michoacán, Mexico.
authors.forename: Jesús
authors.initials: J
authors.lastname: Campos-García
authors.affiliation: Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana, Morelia, Michoacán, Mexico.
authors.forename: Martha I
authors.initials: MI
authors.lastname: Ramírez-Díaz
authors.affiliation: Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana, Morelia, Michoacán, Mexico.. Electronic address: cvega1999@yahoo.com.
authors.forename: Carlos
authors.initials: C
authors.lastname: Cervantes
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D002104:Cadmium / Q000494:pharmacology / Q000633:toxicity; D003001:Cloning, Molecular; D024881:Drug Resistance, Bacterial; D015964:Gene Expression Regulation, Bacterial; D023061:Gene Order; D016685:Mitomycin / Q000494:pharmacology; D010957:Plasmids / Q000235:genetics*; D019704:Protein Disulfide-Isomerases / Q000737:chemistry / Q000235:genetics*; D011550:Pseudomonas aeruginosa / Q000235:genetics; D013879:Thioredoxins / Q000737:chemistry / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D002104:Cadmium; D016685:Mitomycin; D013879:Thioredoxins; D019704:Protein Disulfide-Isomerases
keywords: Cadmium resistance; Disulfide bonds; Stationary phase; Thioredoxin; pUM505 plasmid