• Toxicological Research
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• 제18권4호
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• pp.341-347
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• 2002

Hypertension is a multifactorial disorder in which the genetic and environmental factors are involved. In a view of the effects for hypertension as a risk factor for hypertension, we investigated the genotype and allele frequencies in the four RFLPs of the apo AI-CIII-AIV gene cluster (G to A mutation at position -75 in the apo AI promoter SstI RFLP in the ape CIII gene and HincII and HinfI RFLPs in the apo AIV gene) in the Korean patients with hypertension and normal controls. The AA genotype frequency of the G to A promoter polymorphism in hypertensives was significantly higher than that of normotensives (P < 0.05). None of the other polymorphisms showed a difference in genotype frequency between two groups. Therefore, our result suggest that the G to A promoter polymorphism of the ape AI gene may be useful as genetic marker in the ethiology of hypertension.

• Journal of Microbiology and Biotechnology
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• 제19권9호
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• pp.881-887
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• 2009

Forty-four eicosapentaenoic acid (EPA)-producing microbial strains were isolated from the intestines of marine fishes. Among them, one strain showing a maximum level of EPA (4.78% of total fatty acids) was identified as Shewanella sp. BR-2 on the basis of its 168 rRNA sequence. The EPA content reached a maximum level during the mid-exponential phase of cell growth, and gradually decreased with further growth of the cells. A cosmid DNA including the EPA biosynthesis gene cluster consisting of pfaA-E was isolated from a cosmid library of genomic DNA of Shewanella sp. BR-2, named pCosEPA-BR2. An E. coli clone harboring pCosEPA-BR2 produced EPA at a maximum level of 7.5% of total fatty acids, confirming the EPA biosynthesis activity of the cloned gene cluster.

• Journal of Microbiology and Biotechnology
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• 제15권4호
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• pp.728-733
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• 2005

To elucidate the question of whether biofilm formed by the intercellular adhesion (ica) gene cluster has influences on antibiotic resistance in Staphylococcus epidermidis, we compared 124 skin strains with strains isolated from 50 blood cultures that cause septicemic diseases. The results revealed that the blood culture isolates were more resistant to the antibiotics tested than the saprophytic isolates. Moreover, antibiotic multiresistance was more prevalent in the clinical isolates. In the blood culture isolates, $46\%$ of the strains were resistant to three or more antibiotics, whereas only $12\%$ of the saprophytic isolates were resistant to three or more antibiotics. Interestingly, these characteristics were highly correlated with the biofilm formed by the ica gene cluster. In biofilm-producing strains, $84\%$ of the blood culture isolates and $44\%$ of the saprophytic isolates were antibiotic multiresistant, whereas only $22\%=;and\;9\%$, respectively, were antibiotic multiresistant in biofilm-nonproducing strains. Additionally, in the biofilm-producing ica-positive strains, $89\%$ of the blood culture isolates and $57\%$ of the saprophytic isolates were antibiotic multiresistant. However, the rate of the antibiotic multiresistance in the ica-negative strains was very low, thus indicating that the biofim formed by the lea gene cluster in S. epidermidis is an important pathogenic factor in association with the antibiotic multiresistance.

• Genomics & Informatics
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• 제1권1호
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• pp.32-39
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• 2003

We present a latent variable model-based approach to the analysis of gene expression patterns, coupled with topographic clustering. Aspect model, a latent variable model for dyadic data, is applied to extract latent patterns underlying complex variations of gene expression levels. Then a topographic clustering is performed to find coherent groups of genes, based on the extracted latent patterns as well as individual gene expression behaviors. Applied to cell cycle­regulated genes of the yeast Saccharomyces cerevisiae, the proposed method could discover biologically meaningful patterns related with characteristic expression behavior in particular cell cycle phases. In addition, the display of the variation in the composition of these latent patterns on the cluster map provided more facilitated interpretation of the resulting cluster structure. From this, we argue that latent variable models, coupled with topographic clustering, are a promising tool for explorative analysis of gene expression data.

• Journal of Microbiology and Biotechnology
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• 제16권12호
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• pp.1912-1918
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• 2006

Marine bacterium Hahella chejuensis KCTC 2396 simultaneously produced red antibiotic prodigiosin and undecylprodiginine. A complete set of the prodigiosin biosynthetic gene cluster has been cloned, sequenced, and successfully expressed in a heterologous host. Sequence analysis of the gene cluster revealed 14 ORFs showing high similarity to pig and red genes from Serratia spp. and Streptomyces coelicolor A3(2), respectively, and the gene organization was almost: similar to that of pig genes. These genes were named hap for Hahella prodigiosin, and determined to be transcribed as a single operon, by RT-PCR experiment. Based on the hap gene mutagenesis experiments and comparative analysis with pig and red genes, we propose a prodigiosin-biosynthetic pathway in KCTC 2396.

• The Plant Pathology Journal
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• 제24권1호
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• pp.8-16
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• 2008

Aurofusarin is a polyketide pigment produced by some Fusarium species. The PKS12 and GIP1 genes, which encode a putative type I polyketide synthase (PKS) and a fungal laccase, respectively, are known to be required for aurofusarin biosynthesis in Gibberella zeae (anamorph: Fusarium graminearum). The ten additional genes, which are located within a 30 kb region of PKS12 and GIP1 and regulated by a putative transcription factor (GIP2), organize the aurofusarin biosynthetic cluster. To determine if they are essential for aurofusarin production in G. zeae, we have employed targeted gene deletion, complementation, and chemical analyses. GIP7, which encodes O-methyltransferase, is confirmed to be required for the conversion of norrubrofusarin to rubrofusarin, an intermediate of aurofusarin. GIP1-, GIP3-, and GIP8-deleted strains accumulated rubrofusarin, indicating those gene products are essential enzymes for the conversion of rubrofusarin to aurofusarin. Based on the phenotypic changes in the gene deletion strains examined, we propose a possible pathway for aurofusarin biosynthesis in G. zeae. Our results would provide important information for better understanding of naphthoquinone biosynthesis in other fdarnentous fungi as well as the aurofusarin biosynthesis in G. zeae.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2006년도 추계학술대회 및 정기총회
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• pp.32-44
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• 2006

To investigate non-aflatoxin-production of A. oryzae at the molecular level, an aflatoxin biosynthesis gene homolog cluster of RIB 40 was analyzed. Although most genes in the corresponding cluster exhibited from 97 to 99 % similarity to those of Aspergillus flavus, three genes shared 93 % similarity or less. In addition, although slight expression of aflR, positive transcriptional regulator gene, was detected in some A. oryzae strains having seven aflatoxin biosynthesis homologous genes, other genes related to aflatoxin production were not detected. RIB strains were mainly divided into group 1, having seven aflatoxin biosynthesis homologous genes (aflT, nor-i, aflR, norA, avnA, verB, and vbs), and group 2, having three homologous (avnA, verB, and vbs). Partial aflatoxin homologous gene cluster of RIB62 from group 2 was sequenced and compared with that of RIB40 from group 1. RIB62 showed a large deletion upstream of ver-1 with more than half of the aflatoxin homologous gene cluster missing including aflR, a positive transcriptional regulatory gene. Adjacent to the deletion of the aflatoxin homologous gene cluster, RIB62 has a unique sequence of about 8kb and a telomere. Southern analysis of A. oryzae RIB strains with four kinds of probe derived from the unique sequence of RIB62 showed that all group 2 strains have identical hybridizing signals. Polymerase chain reaction with specific primer set designed to amplify the junction between ver-1 and the unique sequence of RIB62 resulted in the same size of DNA fragment only from group 2 strains. Based on these results, we developed a useful genetic tool that distinguishes A. oryzae group 2 strains from the other groups' strains and propose that it might have differentiated from the ancestral strains due to chromosomal breakage.

• Journal of Microbiology and Biotechnology
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• 제28권7호
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• pp.1068-1077
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• 2018

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. High-performance 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.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2014년도 춘계학술대회 및 임시총회
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• pp.27-28
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• 2014

Beauveria bassiana (Cordycipitaceae, Hypocreales, Ascomycota) is an anamorphic fungus having a potential to be used as a biological control agent because it parasitizes a wide range of arthropod hosts including termites, aphids, beetles and many other insects. A number of bioactive secondary metabolites (SMs) have been isolated from B. bassiana and functionally verified. Among them, beauvericin and bassianolide are cyclic depsipeptides with antibiotic and insecticidal effects belonging to the enniatin family. Non-ribosomal peptide synthetases (NRPSs) play a crucial role in the synthesis of these secondary metabolites. NRPSs are modularly organized multienzyme complexes in which each module is responsible for the elongation of proteinogenic and non-protein amino acids, as well as carboxyl and hydroxyacids. A minimum of three domains are necessary for one NRPS elongation module: an adenylation (A) domain for substrate recognition and activation; a tholation (T) domain that tethers the growing peptide chain and the incoming aminoacyl unit; and a condensation (C) domain to catalyze peptide bond formation. Some of the optional domains include epimerization (E), heterocyclization (Cy) and oxidation (Ox) domains, which may modify the enzyme-bound precursors or intermediates. In the present study, we analyzed genomes of B. bassiana and its allied species in Hypocreales to verify the distribution of NRPS-encoding genes involving biosynthesis of beauvericin and bassianolide, and to unveil the evolutionary processes of the gene clusters. Initially, we retrieved completely or partially assembled genomic sequences of fungal species belonging to Hypocreales from public databases. SM biosynthesizing genes were predicted from the selected genomes using antiSMASH program. Adenylation (A) domains were extracted from the predicted NRPS, NRPS-like and NRPS-PKS hybrid genes, and used them to construct a phylogenetic tree. Based on the preliminary results of SM biosynthetic gene prediction in B. bassiana, we analyzed the conserved gene orders of beauvericin and bassianolide biosynthetic gene clusters among the hypocrealean fungi. Reciprocal best blast hit (RBH) approach was performed to identify the regions orthologous to the biosynthetic gene cluster in the selected fungal genomes. A clear recombination pattern was recognized in the inferred A-domain tree in which A-domains in the 1st and 2nd modules of beauvericin and bassianolide synthetases were grouped in CYCLO and EAS clades, respectively, suggesting that two modules of each synthetase have evolved independently. In addition, inferred topologies were congruent with the species phylogeny of Cordycipitaceae, indicating that the gene fusion event have occurred before the species divergence. Beauvericin and bassianolide synthetases turned out to possess identical domain organization as C-A-T-C-A-NM-T-T-C. We also predicted precursors of beauvericin and bassianolide synthetases based on the extracted signature residues in A-domain core motifs. The result showed that the A-domains in the 1st module of both synthetases select D-2-hydroxyisovalerate (D-Hiv), while A-domains in the 2nd modules specifically activate L-phenylalanine (Phe) in beauvericin synthetase and leucine (Leu) in bassianolide synthetase. antiSMASH ver. 2.0 predicted 15 genes in the beauvericin biosynthetic gene cluster of the B. bassiana genome dispersed across a total length of approximately 50kb. The beauvericin biosynthetic gene cluster contains beauvericin synthetase as well as kivr gene encoding NADPH-dependent ketoisovalerate reductase which is necessary to convert 2-ketoisovalarate to D-Hiv and a gene encoding a putative Gal4-like transcriptional regulator. Our syntenic comparison showed that species in Cordycipitaceae have almost conserved beauvericin biosynthetic gene cluster although the gene order and direction were sometimes variable. It is intriguing that there is no region orthologous to beauvericin synthetase gene in Cordyceps militaris genome. It is likely that beauvericin synthetase was present in common ancestor of Cordycipitaceae but selective gene loss has occurred in several species including C. militaris. Putative bassianolide biosynthetic gene cluster consisted of 16 genes including bassianolide synthetase, cytochrome P450 monooxygenase, and putative Gal4-like transcriptional regulator genes. Our synteny analysis found that only B. bassiana possessed a bassianolide synthetase gene among the studied fungi. This result is consistent with the groupings in A-domain tree in which bassianolide synthetase gene found in B. bassiana was not grouped with NRPS genes predicted in other species. We hypothesized that bassianolide biosynthesizing cluster genes in B. bassiana are possibly acquired by horizontal gene transfer (HGT) from distantly related fungi. The present study showed that B. bassiana is the only species capable of producing both beauvericin and bassianolide. This property led to B. bassiana infect multiple hosts and to be a potential biological control agent against agricultural pests.

• KSBB Journal
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• 제11권1호
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• pp.115-123
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• 1996

zooglan생합성에 필수적인 gene cluster를 clone하기 위해 2종류의 변이주가 분리되었다. Zoogloea ramigera 115는 협막형 다당(주로 zooglan)을 생산한다. 115 균주로 접합시키고 생산물을 용이하게 분리하기 위하여 반복된 원심분리와 선별을 통해 협막을 만들지 않는 slime형 생산균주를 분리하였다. 세포외 다당 생산 능력이 결여된 변이주를 전통적인 transposon(Tn5) 기술을 사용하여 얻었고 달라진 colony 형태와 celluflour결합 성질에 의해 선별하였다. 이들 변이주들은 범용숙주범위 cosmid vector안에 건설된 Z.ramigera 115slime gene library 와 helper plasmid로의 3양친 접합에 의해 보상되었다.