title: Transports of acetate and haloacetate in Burkholderia species MBA4 are operated by distinct systems.
abstract: BACKGROUND
  Acetate is a commonly used substrate for biosynthesis while monochloroacetate is a structurally similar compound but toxic and inhibits cell metabolism by blocking the citric acid cycle. In Burkholderia species MBA4 haloacetate was utilized as a carbon and energy source for growth. The degradation of haloacid was mediated by the production of an inducible dehalogenase. Recent studies have identified the presence of a concomitantly induced haloacetate-uptake activity in MBA4. This uptake activity has also been found to transport acetate. Since acetate transporters are commonly found in bacteria it is likely that haloacetate was transported by such a system in MBA4.
  
  
  RESULTS
  The haloacetate-uptake activity of MBA4 was found to be induced by monochloroacetate (MCA) and monobromoacetate (MBA). While the acetate-uptake activity was also induced by MCA and MBA, other alkanoates: acetate, propionate and 2-monochloropropionate (2MCPA) were also inducers. Competing solute analysis showed that acetate and propionate interrupted the acetate- and MCA- induced acetate-uptake activities. While MCA, MBA, 2MCPA, and butyrate have no effect on acetate uptake they could significantly quenched the MCA-induced MCA-uptake activity. Transmembrane electrochemical potential was shown to be a driving force for both acetate- and MCA- transport systems.
  
  
  CONCLUSIONS
  Here we showed that acetate- and MCA- uptake in Burkholderia species MBA4 are two transport systems that have different induction patterns and substrate specificities. It is envisaged that the shapes and the three dimensional structures of the solutes determine their recognition or exclusion by the two transport systems.
authors.affiliation: Molecular Microbiology Laboratory, School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, Hong Kong.
authors.forename: Xianbin
authors.initials: X
authors.lastname: Su
authors.forename: Ka-Fai
authors.initials: KF
authors.lastname: Kong
authors.forename: Jimmy S H
authors.initials: JS
authors.lastname: Tsang
mesh_terms: D000085:Acetates / Q000378:metabolism*; D019342:Acetic Acid / Q000378:metabolism*; D001692:Biological Transport; D019117:Burkholderia / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D053858:Metabolic Networks and Pathways / Q000235:genetics*; D015533:Transcriptional Activation
chemical_list: D000085:Acetates; C006972:chloroacetic acid; C016274:bromoacetate; D019342:Acetic Acid