Mutation of<i>rpoS</i>enhances<i>Pseudomonas</i>sp. KL28 growth at higher concentrations of<i>m</i>-cresol and changes its surface-related phenotypes

Yun, Ji In,Cho, Kyoung Mi,Kim, Jin-Kyoo,Lee, Soo O.,Cho, Kyungyun,Lee, Kyoung Oxford University Press 2007 FEMS microbiology letters Vol.269 No.1

<P>A Tn5 transposon mutant was isolated of the alkylphenol degrader Pseudomonas sp. KL28 that showed increased growth at higher levels of m-cresol on solid and in liquid cultures. The transposon was inserted at the 5'-terminus of rpoS, which encodes a stationary-phase sigma factor. When grown on agar plates, the rpoS mutant developed prominent wrinkles, especially at lower temperatures, and spread faster on soft agar. In addition, the rpoS mutant had enhanced biofilm-forming ability that was not due to self-produced diffusible signals.</P>

점액세균의 이차대사산물

현혜숙,조경연,Hyun, Hyesook,Cho, Kyungyun 한국미생물학회 2018 미생물학회지 Vol.54 No.3

점액세균은 포식활동, 자기방어, 세포 간 신호전달 및 아직까지 알려지지 않은 다른 기능을 위해 다양한 이차대사산물을 생산한다. 점액세균에서 분리된 많은 이차대사산물들은 독특한 작용기작을 가지며 항암, 항세균, 항진균 등과 같은 약학적으로 유용한 생리활성을 보인다. 따라서 전 세계적으로 많은 점액세균 균주들이 분리되었고 이들로부터 다양한 생리활성물질들이 탐색되었다. 하지만 16S rRNA 데이터베이스 분석에 의하면 야생에는 지금까지 분리된 종류 이외에도 다양한 점액세균 종류들이 존재할 것으로 추정되며, 유전체 서열 분석에 의하면 각 점액세균들은 기존에 알려진 물질보다 더 많은 물질을 생산할 수 있는 능력이 있는 것으로 나타났다. 본 총설에서는 점액세균 유래 이차대사산물들과 이들의 유전자, 점액세균에서의 기능, 생합성 유전자의 발현을 조절하는 전사조절인자 등에 대한 최근까지의 연구 현황을 살펴보았다. Myxobacteria produce diverse secondary metabolites for predation, self-defense, intercellular signaling, and other unknown functions. Many secondary metabolites isolated from myxobacteria show pharmaceutically useful bioactivity such as anticancer, antibacterial, and antifungal activities with a unique mechanism of action. Therefore, a large number of myxobacterial strains have been isolated globally and many bioactive compounds have been purified from them. However, 16S rRNA database analysis indicates that there are far more types of myxobacterial species in the wild than have ever been isolated, and genome sequence analysis suggests that each myxobacterium is capable of producing much more metabolites than already known. In this article, the current status of studies on the secondary metabolites from myxobacteria, their biosynthetic genes, biological functions, and transcriptional regulatory factors governing gene expression were reviewed.

Polymer/Perovskite<b>-</b>Type Nanoparticle Multilayers with Multi<b></b>electric Properties Prepared from Ligand Addition-Induced Layer<b>-</b>by<b>-</b>Layer Assembly

Kim, Younghoon,Kook, Kyungyun,Hwang, Sun Kak,Park, Cheolmin,Cho, Jinhan American Chemical Society 2014 ACS NANO Vol.8 No.3

<P>We introduce an adsorption mechanism for a layer-by-layer (LbL) assembly (<I>i</I>.<I>e</I>., a <I>ligand addition-induced LbL assembly</I>) and demonstrate that the (polymer/perovskite nanoparticle (NP))<SUB><I>n</I></SUB> nanocomposite films based on the ligand addition LbL exhibit ferroelectric and resistive switching properties. Oleic acid (OA)-stabilized BaTiO<SUB>3</SUB> NPs (OA-BTO NPs) with a size of approximately 8 nm were LbL-assembled with amine-functionalized dendrimers (NH<SUB>2</SUB>-dendrimers) using the high affinity between NH<SUB>2</SUB> moieties and Ti ions. The ferroelectric properties of the (NH<SUB>2</SUB>-dendrimer/OA-BTO NP)<SUB><I>n</I></SUB> multilayers were generated by the Ti disorder in the OA-BTO NP unit cell despite the use of sub-10 nm OA-BTO NPs (<I>i</I>.<I>e</I>., OA-BTO NPs), which are near the critical size for ferroelectric properties. Additionally, the (NH<SUB>2</SUB>-dendrimer/OA-BTO NP)<SUB><I>n</I></SUB> multilayers sandwiched between the bottom (platinum) and top (silver or tungsten) electrodes exhibited a resistive switching memory at a relatively low operating voltage below 2 V with a switching speed of approximately 100 ns and an ON/OFF current ratio of approximately 10<SUP>4</SUP>. Furthermore, the ferroelectric and resistive switching properties could be further improved by controlling the bilayer number (<I>n</I>). We believe that our approach can provide a basis for designing and exploiting multifunctional memory electronics based on a variety of perovskite NPs with ferroelectric properties.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2014/ancac3.2014.8.issue-3/nn405988d/production/images/medium/nn-2013-05988d_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn405988d'>ACS Electronic Supporting Info</A></P>

Ssg, a putative glycosyltransferase, functions in lipo- and exopolysaccharide biosynthesis and cell surface-related properties in Pseudomonas alkylphenolia.

Veeranagouda, Yaligara,Lee, Kyoung,Cho, Ah Ra,Cho, Kyungyun,Anderson, Erin M,Lam, Joseph S Published by Elsevier/North Holland on behalf of t 2011 FEMS microbiology letters Vol.315 No.1

<P>In the presence of vaporized p-cresol, Pseudomonas alkylphenolia KL28 forms specialized aerial structures (SAS). A transposon mutant of strain KL28 (C23) incapable of forming mature SAS was isolated. Genetic analysis of the C23 mutant revealed the transposon insertion in a gene (ssg) encoding a putative glycosyltransferase, which is homologous to the Pseudomonas aeruginosa PAO1 PA5001 gene. Deletion of ssg in KL28 caused the loss of lipopolysaccharide O antigen and altered the composition of the exopolysaccharide. Wild-type KL28 produced a fucose-, glucose- and mannose-rich exopolysaccharide, while the mutant exopolysaccharide completely lacked fucose and mannose, resulting in an exopolysaccharide with glucose as the major component. The mutant strain showed reduced surface spreading, pellicle and biofilm formation, probably due to the cumulative effect of lipopolysaccharide truncation and altered exopolysaccharide composition. Our results show that the ssg gene of KL28 is involved in both lipopolysaccharide and exopolysaccharide biosynthesis and thus plays an important role in cell surface properties and cell-cell interactions of P. alkylphenolia.</P>

Tubulysins are Essential for the Preying of Ciliates by Myxobacteria

Yu Uisang,Kim Jiha,Park Seohui,Cho Kyungyun 한국미생물학회 2023 The journal of microbiology Vol.61 No.6

Tubulysins are bioactive secondary metabolites produced by myxobacteria that promote microtubule disassembly. Microtubules are required for protozoa such as Tetrahymena to form cilia and flagella. To study the role of tubulysins in myxobacteria, we co-cultured myxobacteria and Tetrahymena. When 4000 Tetrahymena thermophila and 5.0 × 108 myxobacteria were added to 1 ml of CYSE medium and co-cultured for 48 h, the population of T. thermophila increased to more than 75,000. However, co-culturing tubulysin-producing myxobacteria, including Archangium gephyra KYC5002, with T. thermophila caused the population of T. thermophila to decrease from 4000 to less than 83 within 48 h. Almost no dead bodies of T. thermophila were observed in the culture medium. Co-culturing of T. thermophila and the A. gephyra KYC5002 strain with inactivation of the tubulysin biosynthesis gene led to the population of T. thermophila increasing to 46,667. These results show that in nature, most myxobacteria are preyed upon by T. thermophila, but some myxobacteria prey on and kill T. thermophila using tubulysins. Adding purified tubulysin A to T. thermophila changed the cell shape from ovoid to spherical and caused cell surface cilia to disappear.

Effect of gacS and gacA Mutations on Colony Architecture, Surface Motility, Biofilm Formation and Chemical Toxicity in Pseudomonas sp. KL28

Kyung Soon Choi,Yaligara Veeraragouda,Kyung Mi Cho,Soo O Lee,Geuk Rae Jo,Kyungyun Cho,이경 한국미생물학회 2007 The journal of microbiology Vol.45 No.6

GacS and GacA proteins form a two component signal transduction system in bacteria. Here, Tn5 transposon gacS and gacA (Gac) mutants of Pseudomonas sp. KL28, an alkylphenol degrader, were isolated by selecting for smooth colonies of strain KL28. The mutants exhibited reduced ability to migrate on a solid surface. This surface motility does not require the action of flagella unlike the well-studied swarming motility of other Pseudomonas sp. The Gac mutants also showed reduced levels of biofilm and pellicle formation in liquid culture. In addition, compared to the wild type KL28 strain, these mutants were more resistant to high concentrations of m-cresol but were more sensitive to H2O2, which are characteristics that they share with an rpoS mutant. These results indicate that the Gac regulatory cascade in strain KL28 positively controls wrinkling morphology, biofilm formation, surface translocation and H2O2 resistance, which are important traits for its capacity to survive in particular niches.

Effects of Myxococcus fulvus KYC4048 Metabolites on Breast Cancer Cell Death

( Chayul Lee ),( Sanghyun Park ),( Ikhbayar Ayush ),( Kyungyun Cho ),( Sung Soo Kim ),( Insug Kang ),( Wonchae Choe ),( Yoon-seong Kim ),( Kyung-sik Yoon ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 Journal of microbiology and biotechnology Vol.28 No.5

Using MCF7 breast cancer cells, we tested the anticancer activity of metabolites from 130 strains of myxobacteria newly isolated in South Korea. Of these, three strains whose metabolites had high anticancer activity and low cell toxicity were selected and identified by their fruiting body morphology, cell morphology, and 16S rRNA sequence. Strains KYC4030 and KYC4048 were determined to be Myxococcus fulvus, whereas strain KYC4081 was identified as Corallococcus coralloides. We found that metabolites of M. fulvus KYC4048 demonstrated no toxicity in normal cells but specifically induced cancer cell death by suppressing the expression of WNT2B. This discovery highlights the value of assessing the metabolic and biomedical potential of myxobacteria, even those that are already known but were isolated from new areas, and the possible use of metabolites from M. fulvus KYC4048 in cancer treatment.

Identification of the Phenalamide Biosynthetic Gene Cluster in Myxococcus stipitatus DSM 14675

( Suhyun Park ),( Hyesook Hyun ),( Jong Suk Lee ),( Kyungyun Cho ) 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.9

Phenalamide is a bioactive secondary metabolite produced by Myxococcus stipitatus. We identified a 56 kb phenalamide biosynthetic gene cluster from M. stipitatus DSM 14675 by genomic sequence analysis and mutational analysis. The cluster is comprised of 12 genes (MYSTI_04318- MYSTI_04329) encoding three pyruvate dehydrogenase subunits, eight polyketide synthase modules, a non-ribosomal peptide synthase module, a hypothetical protein, and a putative flavin adenine dinucleotide-binding protein. Disruption of the MYSTI_04324 or MYSTI_04325 genes by plasmid insertion resulted in a defect in phenalamide production. The organization of the phenalamide biosynthetic modules encoded by the fifth to tenth genes (MYSTI_04320- MYSTI_04325) was very similar to that of the myxalamid biosynthetic gene cluster from Stigmatella aurantiaca Sg a15, as expected from similar backbone structures of the two substances. However, the loading module and the first extension module of the phenalamide synthase encoded by the first to fourth genes (MYSTI_04326-MYSTI_04329) were found only in the phenalamide biosynthetic gene cluster from M. stipitatus DSM 14675.

Myxococcus stipitatus DSM 14675의 melithiazol 생합성 유전자 분석

현혜숙 ( Hyesook Hyun ),박수현 ( Soohyun Park ),조경연 ( Kyungyun Cho ) 한국미생물생명공학회(구 한국산업미생물학회) 2016 한국미생물·생명공학회지 Vol.44 No.3

Melithiazol은 점액세균 Melitangium lichenicola, Archangium gephyra, Myxococcus stipitatus에 의해 생산되는 항진균 물질이다. M. lichenicola의 melithiazol 생합성 유전자는 이미 알려져 있지만, A. gephyra와 M. stipitatus의 melithiazol 생합성 유전자들은 아직까지 밝혀져 있지 않다. 본 연구에서는 유전체 서열 분석과 돌연변이 분석을 통해 M. stipitatus DSM 14675 균주로부터 37.3 kb 크기의 melithiazol 생합성 유전자군을 발견하였다. 이 유전자군은 9개(MYSTI_04973-MYSTI_04965)의 유전자로 구성되어 있는데, 4개의 polyketide synthase 모듈과 3개의 nonribosomal peptide synthase 모듈, 그리고 fumarylacetoacetate hydrolase, S-adenosylmethionine-dependent methyltransferase, nitrilase를 암호화하는 것으로 분석되었다. 플라스미드 삽입 돌연변이를 통해 MYSTI_04972 유전자 또는 MYSTI_04973를 불활성화시켰을 때 melithiazol 생산능이상실되었다. MYSTI_04972부터 MYSTI_04965까지의 8개 유전자가 암호화하는 melithiazol 생합성 모듈의 구성은 M. lichenicola Me l46에서와 유사하였다. 하지만 첫 번째 유전자(MYSTI_04973)에 의해 암호화되는 로딩 모듈의 구성은 M. lichenicola Me l46과 달랐는데, 이러한 차이는 M. stipitatus 균주들이 어떻게 M. lichenicola Me l46과는 다른구조의 melithiazol 유도체들을 생산하는지 설명해준다. Melithiazols are antifungal substances produced by the myxobacteria Melitangium lichenicola, Archangium gephyra, and Myxococcus stipitatus. Melithiazol biosynthetic genes have been identified in M. lichenicola, but not in A. gephyra and M. stipitatus until now. We identified a 37.3-kb melithiazol biosynthetic gene cluster from M. stipitatus DSM 14675 using genome sequence analysis and mutational analysis. The cluster is comprised of 9 genes (MYSTI_04973 to MYSTI_04965) that encode 4 polyketide synthase modules, 3 nonribosomal peptide synthase modules, a putative fumarylacetoacetate hydrolase, a putative S adenosylmethionine- dependent methyltransferase, and a putative nitrilase. Disruption of the MYSTI_04972 or MYSTI_ 04973 gene by plasmid insertion resulted in defective melithiazol production. The organization of the melithiazol biosynthetic modules encoded by 8 genes from MYSTI_04972 to MYSTI_04965 was similar to that in M. lichenicola Me l46. However, the loading module encoded by the first gene (MYSTI_04973) was different from that of M. lichenicola Me l46, explaining the difference in the production of melithiazol derivatives between the M. lichenicola Me l46 and M. stipitatus strains.

Genetic and Functional Analyses of the DKxanthene Biosynthetic Gene Cluster from Myxococcus stipitatus DSM 14675

( Hyesook Hyun ),( Sunjin Lee ),( Jong Suk Lee ),( Kyungyun Cho ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 Journal of microbiology and biotechnology Vol.28 No.7

DKxanthenes are a class of yellow secondary metabolites produced by myxobacterial genera Myxococcus and Stigmatella. We identified a putative 49.5 kb DKxanthene biosynthetic gene cluster from Myxococcus stipitatus DSM 14675 by genomic sequence and mutational analyses. The cluster consisted of 15 genes (MYSTI_06004-MYSTI_06018) encoding polyketide synthases, non-ribosomal peptide synthases, and proteins with unknown functions. Disruption of the genes by plasmid insertion resulted in defects in the production of yellow pigments. Highperformance liquid chromatography and liquid chromatography-tandem mass spectrometry analyses indicated that the yellow pigments produced by M. stipitatus DSM 14675 might be novel DKxanthene derivatives. M. stipitatus did not require DKxanthenes for the formation of heat-resistant viable spores, unlike Myxococcus xanthus. Furthermore, DKxanthenes showed growth inhibitory activity against the fungi Aspergillus niger, Candida albicans, and Rhizopus stolonifer.