title: Expression of the six chromate ion transporter homologues of Burkholderia xenovorans LB400.
abstract: The chromate ion transporter (CHR) superfamily comprises transporters that confer chromate resistance by extruding toxic chromate ions from cytoplasm. Burkholderia xenovorans strain LB400 has been reported to encode six CHR homologues in its multireplicon genome. We found that strain LB400 displays chromate-inducible resistance to chromate. Susceptibility tests of Escherichia coli strains transformed with cloned B. xenovorans chr genes indicated that the six genes confer chromate resistance, although under different growth conditions, and suggested that expression of chr genes is regulated by sulfate. Expression of chr genes was measured by quantitative reverse transcription-PCR (RT-qPCR) from total RNA of B. xenovorans LB400 grown under different concentrations of sulfate and exposed or not to chromate. The chr homologues displayed distinct expression levels, but showed no significant differences in transcription under the various sulfate concentrations tested, indicating that sulfate does not regulate chr gene expression in B. xenovorans. The chrA2 gene, encoded in the megaplasmid, was the only chr gene whose expression was induced by chromate and it was shown to constitute the chromate-responsive chrBACF operon. These data suggest that this determinant is mainly responsible for the B. xenovorans LB400 chromate resistance phenotype.
authors.affiliation: Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana, Morelia, Michoacán, Mexico.
authors.forename: Yaned M
authors.initials: YM
authors.lastname: Acosta-Navarrete
authors.affiliation: Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana, Morelia, Michoacán, Mexico.
authors.forename: Yhoana L
authors.initials: YL
authors.lastname: León-Márquez
authors.affiliation: Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana, Morelia, Michoacán, Mexico.
authors.forename: Karina
authors.initials: K
authors.lastname: Salinas-Herrera
authors.affiliation: Laboratorio Estatal de Salud Pública, Secretaría de Salud de Michoacán, Morelia, Michoacán, Mexico.
authors.forename: Irvin E
authors.initials: IE
authors.lastname: Jácome-Galarza
authors.affiliation: Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana, Morelia, Michoacán, Mexico.
authors.forename: Víctor
authors.initials: V
authors.lastname: Meza-Carmen
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.
authors.forename: Carlos
authors.initials: C
authors.lastname: Cervantes
mesh_terms: D019117:Burkholderia / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D002840:Chromates / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D020869:Gene Expression Profiling; D007477:Ions / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013431:Sulfates / Q000378:metabolism
chemical_list: D002840:Chromates; D007477:Ions; D026901:Membrane Transport Proteins; D011994:Recombinant Proteins; D013431:Sulfates