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Toxoflavin lyase enzyme as a marker for selecting potato plant transformants.
Kim, Mi-Sun,Kim, HyunSoon,Moon, Jae Sun,Hwang, Ingyu,Joung, Hyouk,Jeon, Jae-Heung Japan Society for Bioscience, Biotechnology, and A 2012 Bioscience, biotechnology, and biochemistry Vol.76 No.12
<P>This study established a new system for potato transformation using toxoflavin as selection agent and toxoflavin lyase (tflA) as selectable marker gene. Potato plants expressing tflA was successfully transformed on toxoflavin medium with 27% efficiency, similar to that for the hygromycin/hpt selection system. The transgenic potato expressing tflA also showed resistance to Burkholderia glumea infection.</P>
Kim, Jinwoo,Kang, Yongsung,Choi, Okhee,Jeong, Yeonhwa,Jeong, Jae-Eun,Lim, Jae Yun,Kim, Minkyun,Moon, Jae Sun,Suga, Hiroaki,Hwang, Ingyu Blackwell Scientific Publications 2007 Molecular microbiology Vol.64 No.1
<P>Summary</P><P>The bacterium <I>Burkholderia glumae</I> causes rice grain rot by producing toxoflavin, whose expression is regulated by quorum sensing (QS). We report a major deviation from the current paradigm for the regulation of bacterial polar flagellum genes. The <I>N</I>-octanoyl homoserine lactone (C8-HSL)-deficient mutant of <I>B. glumae</I> is aflagellate and has lost the ability to swim and swarm at 37°C. Mutagenesis of the bacterium with the mini-Tn<I>5rescue</I> identified an IclR-type transcriptional regulator, called QsmR, which is important for flagellum formation. TofR, which is a cognate C8-HSL receptor, activated <I>qsmR</I> expression by binding directly to the <I>qsmR</I> promoter region. From the flagellum gene cluster, we identified <I>flhDC</I> homologues that are directly activated by QsmR. FlhDC in turn activates the expression of genes involved in flagellum biosynthesis, motor functions and chemotaxis in <I>B. glumae</I>. Non-motile <I>qsmR</I>, <I>fliA</I> and <I>flhDC</I> mutants produced toxoflavin, but lost pathogenicity for rice. The unexpected discovery of FlhDC in a polarly flagellate bacterium suggests that exceptions to the typical regulatory mechanisms of flagellum genes exist in Gram-negative bacteria. The finding that functional flagella play critical roles in the pathogenicity of <I>B. glumae</I> suggests that either QS or flagellum formation constitutes a good target for the control of rice grain rot.</P>
RNAseq-based Transcriptome Analysis of Burkholderia glumae Quorum Sensing
Kim, Sunyoung,Park, Jungwook,Kim, Ji Hyeon,Lee, Jongyun,Bang, Bongjun,Hwang, Ingyu,Seo, Young-Su The Korean Society of Plant Pathology 2013 Plant Pathology Journal Vol.29 No.3
Burkholderia glumae causes rice grain rot and sheath rot by producing toxoflavin, the expression of which is regulated by quorum sensing (QS). The QS systems of B. glumae rely on N-octanoyl homoserine lactone, synthesized by TofI and its cognate receptor TofR, to activate the genes for toxoflavin biosynthesis and an IclR-type transcriptional regulator gene, qsmR. To understand genome-wide transcriptional profiling of QS signaling, we employed RNAseq of the wild-type B. glumae BGR1 with QS-defective mutant, BGS2 (BGR1 tofI::${\Omega}$) and QS-dependent transcriptional regulator mutant, BGS9 (BGR1 qsmR::${\Omega}$). A comparison of gene expression profiling among the wild-type BGR1 and the two mutants before and after QS onset as well as gene ontology (GO) enrichment analysis from differential expressed genes (DEGs) revealed that genes involved in motility were highly enriched in TofI-dependent DEGs, whereas genes for transport and DNA polymerase were highly enriched in QsmR-dependent DEGs. Further, a combination of pathways with these DEGs and phenotype analysis of mutants pointed to a couple of metabolic processes, which are dependent on QS in B. glumae, that were directly or indirectly related with bacterial motility. The consistency of observed bacterial phenotypes with GOs or metabolic pathways in QS-regulated genes implied that integration RNAseq with GO enrichment or pathways would be useful to study bacterial physiology and phenotypes.
Kim, Jinwoo,Oh, Jonghee,Choi, Okhee,Kang, Yongsung,Kim, Hongsup,Goo, Eunhye,Ma, Jun,Nagamatsu, Tomohisa,Moon, Jae Sun,Hwang, Ingyu American Society for Microbiology 2009 Journal of Bacteriology Vol.191 No.15
<B>ABSTRACT</B><P><I>Burkholderia glumae</I> produces toxoflavin, a phytotoxin with a broad host range, which is a key virulence factor in bacterial rice grain rot. Based on genetic analysis, we previously reported that ToxR, a LysR-type regulator, activates both the <I>toxABCDE</I> (toxoflavin biosynthesis genes) and <I>toxFGHI</I> (toxoflavin transporter genes) operons in the presence of toxoflavin as a coinducer. Quorum sensing regulates the expression of the transcriptional activator ToxJ that is required for <I>tox</I> gene expression. Here, we used gel mobility shift and DNase I protection analyses to demonstrate that both ToxR and ToxJ bind simultaneously to the regulatory regions of both <I>tox</I> operons. ToxR and ToxJ both bound to the <I>toxA</I> and <I>toxF</I> regulatory regions, and the sequences for the binding of ToxR to the regulatory regions of both <I>tox</I> operons possessed T-N11-A motifs. Following random mutagenesis of <I>toxR</I>, 10 ToxR mutants were isolated. We constructed a reporter strain, S6K34 (<I>toxR</I>′<I>A</I>′::Ω <I>toxF</I>::Tn<I>3</I>-<I>gusA34</I>) to evaluate which amino acid residues are important for ToxR activity. Several single amino acid substitutions identified residues that might be important for ToxR binding to DNA and toxoflavin binding. When various toxoflavin derivatives were tested to determine whether toxoflavin is a specific coinducer of ToxR in the S6K34 strain, ToxR, together with toxoflavin, conferred <I>toxF</I> expression, whereas 4,8-dihydrotoxoflavin did so only slightly. With these results, we have demonstrated biochemically that <I>B. glumae</I> cells control toxoflavin production tightly by the requirement of both ToxJ and toxoflavin as coinducers of ToxR.</P>
Kim, Jun Sung,Khim, Seunghyun,Yan, Liqin,Manivannan, N,Liu, Yong,Kim, Ingyu,Stewart, G R,Kim, Kee Hoon IOP Pub 2009 Journal of Physics, Condensed Matter Vol.21 No.10
<P>In order to investigate whether magnetism and superconductivity coexist in Co-doped SrFe<SUB>2</SUB>As<SUB>2</SUB>, we have prepared single crystals of SrFe<SUB>2−<I>x</I></SUB>Co<SUB><I>x</I></SUB>As<SUB>2</SUB>, <I>x</I> = 0 and 0.4, and characterized them via x-ray diffraction, electrical resistivity in zero and applied field up to 9 T as well as at ambient and applied pressure up to 1.6 GPa, and magnetic susceptibility. At <I>x</I> = 0.4, there is both magnetic and resistive evidence for a spin density wave transition at 120 K, while <I>T</I><SUB>c</SUB> = 19.5 K—indicating coexistent magnetism and superconductivity. A discussion of how these results compare with reported results, both in SrFe<SUB>2−<I>x</I></SUB>Co<SUB><I>x</I></SUB>As<SUB>2</SUB> and in other doped 122 compounds, is given. </P>