A Phenome-Based Functional Analysis of Transcription Factors in the Cereal Head Blight Fungus, <i>Fusarium graminearum</i>

Son, Hokyoung,Seo, Young-Su,Min, Kyunghun,Park, Ae Ran,Lee, Jungkwan,Jin, Jian-Ming,Lin, Yang,Cao, Peijian,Hong, Sae-Yeon,Kim, Eun-Kyung,Lee, Seung-Ho,Cho, Aram,Lee, Seunghoon,Kim, Myung-Gu,Kim, Yongs Public Library of Science 2011 PLoS pathogens Vol.7 No.10

<▼1><P><I>Fusarium graminearum</I> is an important plant pathogen that causes head blight of major cereal crops. The fungus produces mycotoxins that are harmful to animal and human. In this study, a systematic analysis of 17 phenotypes of the mutants in 657 <I>Fusarium graminearum</I> genes encoding putative transcription factors (TFs) resulted in a database of over 11,000 phenotypes (phenome). This database provides comprehensive insights into how this cereal pathogen of global significance regulates traits important for growth, development, stress response, pathogenesis, and toxin production and how transcriptional regulations of these traits are interconnected. In-depth analysis of TFs involved in sexual development revealed that mutations causing defects in perithecia development frequently affect multiple other phenotypes, and the TFs associated with sexual development tend to be highly conserved in the fungal kingdom. Besides providing many new insights into understanding the function of <I>F. graminearum</I> TFs, this mutant library and phenome will be a valuable resource for characterizing the gene expression network in this fungus and serve as a reference for studying how different fungi have evolved to control various cellular processes at the transcriptional level.</P></▼1><▼2><P><B>Author Summary</B></P><P>Large collections of mutant lines allow for identification of gene functions. Here we constructed a mutant library of 657 putative transcription factors (TFs) through homologous recombination in the head blight fungus, <I>Fusarium graminearum</I>, providing a resource for understanding gene regulation in fungus. By screening these mutants in 17 phenotypic categories, we constructed a dataset of over 11,000 phenotypes. This study provides new insight into understanding multiple phenotypes caused by single TF as well as regulation of gene expression at the transcription level in <I>F. graminearum</I>. Furthermore, our TF mutant library will be a valuable resource for fungal studies through the distribution of mutants and easy access to our phenotypic and genetic data.</P></▼2>

Mitochondrial Carnitine-Dependent Acetyl Coenzyme A Transport Is Required for Normal Sexual and Asexual Development of the Ascomycete Gibberella zeae

Son, Hokyoung,Min, Kyunghun,Lee, Jungkwan,Choi, Gyung Ja,Kim, Jin-Cheol,Lee, Yin-Won American Society for Microbiology 2012 EUKARYOTIC CELL Vol.11 No.9

<B>ABSTRACT</B><P> Fungi have evolved efficient metabolic mechanisms for the exact temporal (developmental stages) and spatial (organelles) production of acetyl coenzyme A (acetyl-CoA). We previously demonstrated mechanistic roles of several acetyl-CoA synthetic enzymes, namely, ATP citrate lyase and acetyl-CoA synthetases (ACSs), in the plant-pathogenic fungus Gibberella zeae . In this study, we characterized two carnitine acetyltransferases (CATs; CAT1 and CAT2) to obtain a better understanding of the metabolic processes occurring in G. zeae . We found that CAT1 functioned as an alternative source of acetyl-CoA required for lipid accumulation in an <I>ACS1</I> deletion mutant. Moreover, deletion of <I>CAT1</I> and/or <I>CAT2</I> resulted in various defects, including changes to vegetative growth, asexual/sexual development, trichothecene production, and virulence. Although CAT1 is associated primarily with peroxisomal CAT function, mislocalization experiments showed that the role of CAT1 in acetyl-CoA transport between the mitochondria and cytosol is important for sexual and asexual development in G. zeae . Taking these data together, we concluded that G. zeae CATs are responsible for facilitating the exchange of acetyl-CoA across intracellular membranes, particularly between the mitochondria and the cytosol, during various developmental stages. </P>

WetA Is Required for Conidiogenesis and Conidium Maturation in the Ascomycete Fungus <i>Fusarium graminearum</i>

Son, Hokyoung,Kim, Myung-Gu,Min, Kyunghun,Lim, Jae Yun,Choi, Gyung Ja,Kim, Jin-Cheol,Chae, Suhn-Kee,Lee, Yin-Won American Society for Microbiology 2014 EUKARYOTIC CELL Vol.13 No.1

<P><I>Fusarium graminearum</I>, a prominent fungal pathogen that infects major cereal crops, primarily utilizes asexual spores to spread disease. To understand the molecular mechanisms underlying conidiogenesis in <I>F. graminearum</I>, we functionally characterized the <I>F. graminearum</I> ortholog of <I>Aspergillus nidulans</I> <I>wetA</I>, which has been shown to be involved in conidiogenesis and conidium maturation. Deletion of <I>F. graminearum</I> <I>wetA</I> did not alter mycelial growth, sexual development, or virulence, but the <I>wetA</I> deletion mutants produced longer conidia with fewer septa, and the conidia were sensitive to acute stresses, such as oxidative stress and heat stress. Furthermore, the survival rate of aged conidia from the <I>F. graminearum</I> <I>wetA</I> deletion mutants was reduced. The <I>wetA</I> deletion resulted in vigorous generation of single-celled conidia through autophagy-dependent microcycle conidiation, indicating that WetA functions to maintain conidial dormancy by suppressing microcycle conidiation in <I>F. graminearum</I>. Transcriptome analyses demonstrated that most of the putative conidiation-related genes are expressed constitutively and that only a few genes are specifically involved in <I>F. graminearum</I> conidiogenesis. The conserved and distinct roles identified for WetA in <I>F. graminearum</I> provide new insights into the genetics of conidiation in filamentous fungi.</P>

Peroxisome function is required for virulence and survival of Fusarium graminearum.

Min, Kyunghun,Son, Hokyoung,Lee, Jungkwan,Choi, Gyung Ja,Kim, Jin-Cheol,Lee, Yin-Won APS Press 2012 Molecular plant-microbe interactions Vol.25 No.12

<P>Peroxisomes are organelles that are involved in a number of important cellular metabolic processes, including the β-oxidation of fatty acids, biosynthesis of secondary metabolites, and detoxification of reactive oxygen species (ROS). In this study, the role of peroxisomes was examined in Fusarium graminearum by targeted deletion of three genes (PEX5, PEX6, and PEX7) encoding peroxin (PEX) proteins required for peroxisomal protein import. PEX5 and PEX7 deletion mutants were unable to localize the fluorescently tagged peroxisomal targeting signal type 1 (PTS1)- and PTS2-containing proteins to peroxisomes, respectively, whereas the PEX6 mutant failed to localize both fluorescent proteins. Deletion of PEX5 and PEX6 resulted in retarded growth on long-chain fatty acids and butyrate, while the PEX7 deletion mutants utilized fatty acids other than butyrate. Virulence on wheat heads was greatly reduced in the PEX5 and PEX6 deletion mutants, and they were defective in spreading from inoculated florets to the adjacent spikelets through rachis. Deletion of PEX5 and PEX6 dropped survivability of aged cells in planta and in vitro due to the accumulation of ROS followed by necrotic cell death. These results demonstrate that PTS1-dependent peroxisomal protein import mediated by PEX5 and PEX6 are critical to virulence and survival of F. graminearum.</P>

Transcription Factor RFX1 Is Crucial for Maintenance of Genome Integrity in <i>Fusarium graminearum</i>

Min, Kyunghun,Son, Hokyoung,Lim, Jae Yun,Choi, Gyung Ja,Kim, Jin-Cheol,Harris, Steven D.,Lee, Yin-Won American Society for Microbiology 2014 EUKARYOTIC CELL Vol.13 No.3

<P>The survival of cellular organisms depends on the faithful replication and transmission of DNA. Regulatory factor X (RFX) transcription factors are well conserved in animals and fungi, but their functions are diverse, ranging from the DNA damage response to ciliary gene regulation. We investigated the role of the sole RFX transcription factor, RFX1, in the plant-pathogenic fungus <I>Fusarium graminearum</I>. Deletion of <I>rfx1</I> resulted in multiple defects in hyphal growth, conidiation, virulence, and sexual development. Deletion mutants of <I>rfx1</I> were more sensitive to various types of DNA damage than the wild-type strain. Septum formation was inhibited and micronuclei were produced in the <I>rfx1</I> deletion mutants. The results of the neutral comet assay demonstrated that disruption of <I>rfx1</I> function caused spontaneous DNA double-strand breaks (DSBs). The transcript levels of genes involved in DNA DSB repair were upregulated in the <I>rfx1</I> deletion mutants. DNA DSBs produced micronuclei and delayed septum formation in <I>F. graminearum</I>. Green fluorescent protein (GFP)-tagged RFX1 localized in nuclei and exhibited high expression levels in growing hyphae and conidiophores, where nuclear division was actively occurring. RNA-sequencing-based transcriptomic analysis revealed that RFX1 suppressed the expression of many genes, including those required for the repair of DNA damage. Taken together, these findings indicate that the transcriptional repressor <I>rfx1</I> performs crucial roles during normal cell growth by maintaining genome integrity.</P>

Functional Analyses of Two Acetyl Coenzyme A Synthetases in the Ascomycete Gibberella zeae

Lee, Seunghoon,Son, Hokyoung,Lee, Jungkwan,Min, Kyunghun,Choi, Gyung Ja,Kim, Jin-Cheol,Lee, Yin-Won American Society for Microbiology 2011 EUKARYOTIC CELL Vol.10 No.8

<B>ABSTRACT</B><P> Acetyl coenzyme A (acetyl-CoA) is a crucial metabolite for energy metabolism and biosynthetic pathways and is produced in various cellular compartments with spatial and temporal precision. Our previous study on ATP citrate lyase (ACL) in Gibberella zeae revealed that ACL-dependent acetyl-CoA production is important for histone acetylation, especially in sexual development, but is not involved in lipid synthesis. In this study, we deleted additional acetyl-CoA synthetic genes, the acetyl-CoA synthetases ( <I>ACS</I> genes <I>ACS1</I> and <I>ACS2</I> ), to identify alternative acetyl-CoA production mechanisms for ACL. The <I>ACS1</I> deletion resulted in a defect in sexual development that was mainly due to a reduction in 1-palmitoyl-2-oleoyl-3-linoleoyl-rac-glycerol production, which is required for perithecium development and maturation. Another ACS coding gene, <I>ACS2</I> , has accessorial functions for <I>ACS1</I> and has compensatory functions for <I>ACL</I> as a nuclear acetyl-CoA producer. This study showed that acetate is readily generated during the entire life cycle of G. zeae and has a pivotal role in fungal metabolism. Because ACSs are components of the pyruvate-acetaldehyde-acetate pathway, this fermentation process might have crucial roles in various physiological processes for filamentous fungi. </P>

ELP3 is involved in sexual and asexual development, virulence, and the oxidative stress response in Fusarium graminearum.

Lee, Yoonji,Min, Kyunghun,Son, Hokyoung,Park, Ae Ran,Kim, Jin-Cheol,Choi, Gyung Ja,Lee, Yin-Won APS Press 2014 Molecular plant-microbe interactions Vol.27 No.12

<P>Fusarium graminearum is an important fungal plant pathogen that causes serious losses in cereal crop yields and mycotoxicoses in humans and livestock. In this study, we characterized an insertion mutant, Z39R9282, with pleiotropic defects in sexual development and virulence. We determined that the insertion occurred in a gene encoding an ortholog of yeast elongator complex protein 3 (ELP3). Deletion of elp3 led to significant defects in sexual and asexual development in F. graminearum. In the elp3 deletion mutant, the number of perithecia formed was reduced and maturation of perithecia was delayed. This mutant also produced morphologically abnormal ascospores and conidia. Histone acetylation in the elp3 deletion mutant was reduced compared with the wild type, which likely caused the developmental defects. Trichothecenes were not produced at detectable levels, and expression of trichothecene biosynthesis genes were significantly reduced in the elp3 deletion mutant. Infection of wheat heads revealed that the elp3 deletion mutant was unable to spread from inoculated florets to neighboring spikelets. Furthermore, the elp3 deletion mutant was more sensitive to oxidative stress than the wild type, and the expression of putative catalase genes was reduced. We demonstrate that elp3 functions in sexual and asexual development, virulence, and the oxidative stress response of F. graminearum by regulating the expression of genes involved in these various developmental processes.</P>

FTTH망에서 호스트멀티캐스트를 이용한 개인 인터넷 방송 시스템 설계 및 구현

김경태(Kyoungtae Kim),손승철(Seungchul Son),허권(Kwon Heo),이형옥(Hyungok Lee),김경훈(Kyunghun Kim),남지승(Jiseung Nam) 한국정보과학회 2006 한국정보과학회 학술발표논문집 Vol.33 No.1

본 논문에서는 FTTH 환경에 의해 가입자까지 100Mbps 이상의 대역폭을 보장하면서 실제 서비스 되어질 수 있는 응용 시스템인 개인 인터넷 방송 시스템을 호스트 멀티캐스트 Scheme을 이용하여 설계 및 구현하였다. 전송 방식인 호스트 멀티캐스트에 대해 알아보고 개인 인터넷 방송 서버(Contents Provider)와 클라이언트(Host)의 구조에 효율적인 호스트 멀티캐스트 알고리즘인 Data Delivery Tree Algorithm(DDTA)를 제안하고, DDTA 알고리즘이 FTTH 환경에서 HDTV급 고화질 영상을 전송할 수 있는 개인 인터넷 방송 시스템에 효율적인 알고리즘이라는 것을 보인다.

Risk assessment of endocrine disruptors in cosmetics

Kim YoungOk,Lee JeongPyo,Choi SangSook,Son KyungHun,Yang SeongJun,Kim ShinOk,Paek OckJin,Cho HyeonSeo 大韓藥學會 2002 大韓藥學會 總會 및 學術大會 Vol.2002 No.2

Binary code DOE optimization for speckle suppression in a laser display

Yurlov, Victor,Lapchuk, Anatoliy,Han, Kyunghun,Son, Seong-Jin,Kim, Bok Hyeon,Yu, Nan Ei OSA OPTICAL SOCIETY OF AMERICA 2018 Applied optics Vol.57 No.30