Isolation and characterization of a novel haloacid permease from Burkholderia cepacia MBA4

Abstract

Burkholderia cepacia MBA4 is a bacterium that can utilize 2-haloacids as carbon and energy sources for growth. It has been proposed that dehalogenase-associated permease mediates the uptake of haloacid. In this paper, we report the first cloning and characterization of such a haloacid permease. The structural gene, designated deh4p, was found 353 bases downstream of the dehalogenase gene deh4a. Quantitative analysis of the expression of deh4p showed that it was induced by monochloroacetate (MCA), to a level similar to the MCA-induced level of deh4a. The nucleotide sequence of deh4p was determined, and an open reading frame of 1,656 bp encoding a putative peptide of 552 amino acids was identified. Deh4p has a putative molecular weight of 59,414 and an isoelectric point of 9.88. Deh4p has the signatures of sugar transport proteins and integral membrane proteins of the major facilitator superfamily. Uptake of [14C]MCA into the cell was Deh4p dependent. Deh4p has apparent K ms of 5.5 and 8.9 μM and Vmaxs of 9.1 and 23.1 nmol mg-1 min-1 for acetate and MCA, respectively. A mutant with a transposon-inactivated haloacid operon failed to grow on MCA even when deh4a was provided in trans. Copyright © 2007, American Society for Microbiology. All Rights Reserved.