Identification of a haloacid inducible glycolate operon in a

THE UNIVERSITY OF HONG KONG
SCHOOL OF BIOLOGICAL SCIENCES
Identification of a haloacid inducible glycolate operon in a Burkholderia caribensis
Ms. Zheng Nan
PhD student, School of Biological Sciences, HKU
Supervisor: Dr. Jimmy S. H. Tsang
On Friday 12 December, 2014 at 3:30pm
Room 6N-11, Kadoorie Biological Sciences Building
Abstract
Burkholderia caribensis MBA4 was able to utilize toxic haloacids as the carbon
and energy sources. Monochloroacetate (MCA) is one of them. Genes of an inducible
dehalogenase (Deh4a) and a haloacid transporter (Deh4p) were found arranged in a
transcript. They were involved in dehalogenation and uptake processes, respectively.
To further understand the metabolism of MCA in MBA4. The metabolism of MCA
metabolite: glycolate has been studied recently. Glyoxylate was produced from
oxidation of glycolate by glycolate oxidase. Three glycolate oxidases were found in
Burkholderia species MBA4: ETY79681-79, ETY80273-1 and ETY 84258-61. Reads
per kilobase transcript per million (RPKM) of the analysis of RNA-seq technology
indicated that ETY79681-79 was produced at a similar level regardless of the carbon
sources glycolate or MCA. The RPKM values of ETY80273-1 were lower in
chloroacetate- than in glycolate-grown cells and its putative regulator ETY80275 also
showed its RPKM value lower in chloroacetate-grown cell. This is quite conventional,
as expression of glycolate oxidase of model microorganism, such as Escherichia coli
K-12, was induced by its substrate: glycolate. Most interestingly, ETY 84258-61
showed its highest value in chloroacetate- grown cells which was around 10 folds of
that in glycolate-grown cells. A malate synthase G gene, ETY84262, situated
downstream of ETY 84258-61gave similar response as that of ETY 84258-61. Its
putative regulator GlcC gene, ETY84257 were found, located upstream of ETY
84258-61. ETY84257 was found to express more in chloroacetate-grown cells, which
is opposite to that of the ETY80275. The behaviors of the regulators were possibly
different. With the differential expression, ETY84257, it is further characterized to
have a complete picture of the regulatory mechanism of this glycolate operon.

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