Review : Membrane-bound transcription factors in Arabidopsis

박충모,김윤성 한국생화학분자생물학회 (구 한국생화학회) 2006 생화학분자생물학회 소식 Vol.26 No.3

MAP3Kθ1 is Involved in Abscisic Acid Signaling in Drought Tolerance and Seed Germination in Arabidopsis

박충모 한국식물학회 2020 Journal of Plant Biology Vol.63 No.1

Mitogen-activated protein kinase cascades play pivotal roles in mediating environmental stress responses and plant development. In this study, a loss-of-function mutant of Arabidopsis, map3kθ1, exhibited wider stomatal openings, reduced root elongation, and increased seed germination rate compared with its wild type under exogenous abscisic acid (ABA) treatment. MAP3Kθ1 encodes a MAP kinase kinase kinase (MAP3K) with unknown function. Two overexpression lines of MAP3Kθ1 exhibited inhibited seed germination and narrowed stomata, which were aggravated by ABA treatment. Upregulation of MAP3Kθ1 also resulted in stronger drought tolerance, whereas map3kθ1 was more sensitive to water defciency, partially due to diferences in the water-holding capacity of leaves. The MAP3Kθ1-overexpressing lines also showed a greater ability to maintain root elongation under exogenous ABA. Expression of MAP3Kθ1 was inhibited by ABA, H2O2, and methyl viologen treatments in roots. The MAP3Kθ1-overexpressing lines accumulated more ABA by promoting its biogenesis and inhibiting its catabolism, whereas the map3kθ1 mutant accumulated less ABA, compared with wild-type plants. These fndings indicate that MAP3Kθ1 promotes ABA accumulation to regulate stomatal movement, root elongation, and seed germination, while the ABA–H2O2 signaling module inhibits MAP3Kθ1 expression through feedback regulation.

Plant Thermomorphogenic Adaptation to Global Warming

박충모,박영준 한국식물학회 2020 Journal of Plant Biology Vol.63 No.1

Plants are capable of actively adapting to a variety of environmental signals by adjusting physiological activities, growth behaviors, and architectural morphology. Temperatures are one of the major environmental factors that extensively afect plant growth and developmental processes. A suite of signaling mediators and underlying molecular mechanisms governing plant adaptation to stressful high and low temperatures have been explored through molecular genetic approaches and global-scale gene expression screening in recent decades. Notably, it is known that ambient temperature changes even by a few degrees also profoundly afect plant developmental and morphological traits. In particular, in response to ambient warm temperatures, plants exhibit distinct morphological adjustments, such as stem elongation, increase of leaf hyponasty, and formation of small, slender leaves, which are collectively termed thermomorphogenesis. Plant thermomorphogenesis is intimately associated with global warming, which represents a steady increase of the average global temperatures and is emerging as a world-wide ecological concern because of its impacts on plant vegetation and crop productivity. In this minireview, we summarize recent progress in the feld and discuss practical insights into how plants cope with temperature changes to sustain optimal growth and adaptive behaviors.

A Competitive Peptide Inhibitor KIDARI Negatively Regulates HFR1 by Forming Nonfunctional Heterodimers in Arabidopsis Photo-morphogenesis

홍신영,박충모,서필준,류재용,조신해,우제창 한국분자세포생물학회 2013 Molecules and cells Vol.35 No.1

Dynamic dimer formation is an elaborate means of modulating transcription factor activities in diverse cellular pro-cesses. The basic helix-loop-helix (bHLH) transcription factor LONG HYPOCOTYL IN FAR-RED 1 (HFR1), for example, plays a role in plant photomorphogenesis by forming non-DNA binding heterodimers with PHYTOCHROME-INTERACTING FACTORS (PIFs). Recent studies have shown that a small HLH protein KIDARI (KDR) negatively regulates the HFR1 activity in the process. However, molecular mechanisms underlying the KDR control of the HFR1 activity are unknown. Here, we demonstrate that KDR attenuates the HFR1 activity by competitively forming nonfunctional heterodimers, causing liberation of PIF4 from the transcriptionally inactive HFR1-PIF4 complex. Accordingly, the photomorphogenic hypocotyl growth of the HFR1-overexpres-sing plants can be suppressed by KDR coexpression, as observed in the HFR1-deficient hfr1-201 mutant. These results indicate that the PIF4 activity is modulated through a double layer of competitive inhibition by HFR1 and KDR, which could in turn ensure fine-tuning of the PIF4 activity under fluctuating light conditions.

MicroRNA biogenesis and function in higher plants

정재훈,서필준,박충모 한국식물생명공학회 2009 Plant biotechnology reports Vol.3 No.2

MicroRNAs (miRNAs) are endogenous, noncoding, small RNA molecules consisting of 21–24 nucleotides (nts) that regulate target genes at the posttranscriptional level in plants and animals. In plants, miRNAs negatively regulate target mRNAs containing a highly complementary sequence by either mRNA cleavage or translational repression. MiRNAs are processed from singlestranded precursors containing stem-loop structures by a Dicer-like enzyme and are loaded into silencing complexes, where they act on target mRNAs. Although plant miRNAs were first reported in Arabidopsis 10 years later than animal miRNAs, numerous miRNAs have since been identified from various land plants ranging from mosses to flowering plants, and their roles in diverse aspects of plant developmental processes have been characterized. Furthermore, most of the annotated plant miRNAs are evolutionarily conserved in various plants. In particular, recent functional studies using Arabidopsis mutants have contributed a great deal of information towards establishing a framework for understanding miRNA biogenesis and functional roles. Extensive appraisal of miRNA-directed regulation during a wide array of plant development and plant responses to environmental conditions has confirmed the versatile roles of miRNAs as a key component of plant molecular biology.

An Arabidopsis Homologue of Human Seven-in-Absentia-interacting Protein Is Involved in Pathogen Resistance

김윤성,함병국,백경희,박충모,주남해 한국분자세포생물학회 2006 Molecules and cells Vol.21 No.3

The Floral Repressor BROTHER OF FT AND TFL1 (BFT) Modulates Flowering Initiation under High Salinity in Arabidopsis

Jae Yong Ryu,박충모,서필준 한국분자세포생물학회 2011 Molecules and cells Vol.32 No.3

Floral transition is coordinately regulated by both endo-genous and exogenous cues to ensure reproductive suc-cess under fluctuating environmental conditions. Abiotic stress conditions, including drought and high salinity, also have considerable influence on this developmental process. However, the signaling components and molecular mecha-nisms underlying the regulation of floral transition by environmental factors have not yet been defined. In this work, we show that the Arabidopsis BROTHER OF FT AND TFL1 (BFT) gene, which encodes a member of the FLOWERING LOCUS T (FT)/TERMINAL FLOWER 1 (TFL1) family, regulates floral transition under conditions of high salinity. The BFT gene was transcrip-tionally induced by high salinity in an abscisic acid (ABA)-dependent manner. Transgenic plants overexpressing the BFT gene (35S:BFT) and BFT-deficient mutant (bft-2) plants were phenotypically indistinguishable from Col-0 plants in seed germination and seedling growth under high salinity. In contrast, al-though the floral transition was delayed significantly in Col-0 plants under high salinity, that of the bft-2 mutant was not affected by high salinity. We also observed that expression of the APETALA1 (AP1) gene was suppressed to a lesser degree in the bft-2 mutant than in Col-0 plants. Taken together, our observations suggest that BFT me-diates salt stress-responsive flowering, providing an adaptive strategy that ensures reproductive success under unfavorable stress conditions.

Activation of a Mitochondrial ATPase Gene Induces Abnormal Seed Development in Arabidopsis

Kon Baek,서필준,박충모 한국분자세포생물학회 2011 Molecules and cells Vol.31 No.4

The ATPases associated with various cellular activities (AAA) proteins are widespread in living organisms. Some of the AAA-type ATPases possess metalloprotease activi-ties. Other members constitute the 26S proteasome com-plexes. In recent years, a few AAA members have been implicated in vesicle-mediated secretion, membrane fu-sion, cellular organelle biogenesis, and hypersensitive responses (HR) in plants. However, the physiological roles and biochemical activities of plant AAA proteins have not yet been defined at the molecular level, and regulatory mechanisms underlying their functions are largely unknown. In this study, we showed that overexpression of an Arabidopsis gene encoding a mitochondrial AAA protein, ATPase-in-Seed-Development (ASD), induces morphological and anatomical defects in seed maturation. The ASD gene is expressed at a high level during the seed maturation process and in mature seeds but is repressed rapidly in germinating seeds. Transgenic plants overexpressing the ASD gene are morphologically normal. However, seed formation is severely disrupted in the transgenic plants. The ASD gene is induced by abiotic stresses, such as low temperatures and high salinity, in an abscisic acid (ABA)-dependent manner. The ASD protein possesses ATPase activity and is localized into the mitochondria. Our observations suggest that ASD may play a role in seed maturation by influencing mitochondrial function under abiotic stress.

Preparation of Leaf Mesophyll Protoplasts for Transient Gene Expression in Brachypodium distachyon

Shin-Young Hong,서필준,Shin-Hae Cho,박충모 한국식물학회 2012 Journal of Plant Biology Vol.55 No.5

Transient gene expression systems using protoplasts have been widely used for rapid functional characterization of genes in many plant species. Brachypodium distachyon has recently been employed as a model plant for studies on biofuel grass species and grass crops because of its small genome size, short life-span, and availability of efficient transformation systems. Here, we report the an efficient protocol for the preparation of leaf mesophyll protoplasts from Brachypodium seedlings. We also modified the polyethylene glycol (PEG)-mediated transformation procedure to optimize experimental conditions, such as duration of enzyme digestion, PEG incubation time, and plasmid DNA concentration and size. The green fluorescence protein (GFP)- and β-glucuronidase (GUS)-coding genes were used as reporters to evaluate the feasibility of this transient expression system. We found that the yield of viable protoplasts was highest after 3 h of enzymatic digestion. Viability of enzyme-digested protoplasts was moderately maintained up to 24 h in Mmg preincubation solution. In addition, the highest transient expression of reporter genes was obtained when protoplasts were transformed with 20 μg of plasmid DNA and incubated for 16 h. Together with the recent completion of the Brachypodium genome sequence,the Brachypodium transient expression system using leaf mesophyll protoplasts can be widely used for cellular,molecular, and biochemical studies of genes involved in carbon metabolism and signaling pathways mediating intrinsic and environmental cues.

Phosphorylation Properties of Recombinant OsCPK11, a Calcium-dependent Protein Kinase from Rice

Il-Sang Cho(조일상),Su-Hee Lee(이수희),Chung-Mo Park(박충모),Sung-Ha Kim(김성하) 한국생명과학회 2017 생명과학회지 Vol.27 No.12

식물에서, 칼슘-의존적 단백질 카이네즈(CDPKs)는 Ca<SUP>2+</SUP> 신호전달에서 중요한 Ca<SUP>2+</SUP> 수용체이다. 벼(Oryza sativa L.)의 CDPKs인 3개의 OsCPKs는 생물정보에 대한 분석이 이루어졌으나, OsCPK11 유전자는 연구가 완전히 수행되지 않았다. 다양한 조직에서 OsCPK11 유전자가 전사수준에서 발현한다는 것은 알려져 있으나, 단백질 수준에서 발현과 생화학적인 특징은 잘 알려져 있지 않다. 이 연구는 OsCPK11의 몇 가지 생화학적 특징을 알아보기 위해 이루어졌다. 먼저 in vitro에서 E. coli를 이용하여 GST-OsCPK11를 발현시키고, 카이네즈 활성 측정과 칼슘-의존적 단백질 카이네즈로서 OsCPK11의 생화학적 분석도 수행하였다. OsCPK11은 스스로 자가인산화하며, Ca<SUP>2+</SUP>의 존재 하에서 기질로서 histone III-s와 MBP로 인산기 전달 작용을 수행한다. 재조합 OsCPK11의 활성은 Mg<SUP>2+</SUP>에 의해 영향을 받으며, pH 7.0-7.5에서 최적의 활성을 보인다. 또한 OsCPK11의 활성은 높은 수준의 Ca<SUP>2+</SUP>가 존재하는 조건에서는 Mg<SUP>2+</SUP>, Mn<SUP>2+</SUP>, Na<SUP>+</SUP>의 영향을 받지 않는다. 또한 OsCPK11의 자가인산화는 OsCPK11의 Ca<SUP>2+</SUP> 민감도를 감소시키는 것으로 밝혀졌다. 마지막으로, OsCPK11의 N-말단 다양화 지역으로 토끼 항체를 만들었고, immunoblot을 기초로 polyclonal antibody는 95.5 kD의 GST-OsCPK11를 인식하는 것으로 나타났다. 이 결과는 벼의 Ca<SUP>2+</SUP> 매개 신호전달에서 OsCPK11의 기능을 더 잘 이해하는데 도움을 줄 것이며, 심화 연구를 위해 다양한 OsCPKs의 단백질 정보를 결정하는 것이 필요할 것이다. In plants, calcium (Ca<SUP>2+</SUP>)-dependent protein kinases (CDPKs) are important sensors of Ca<SUP>2+</SUP> signals. Previous research demonstrated the expression of the OsCPK11 gene in various tissues at the transcription level, but its developmental and biochemical functions at the protein level were not determined. This study was aimed to identify biochemical characteristics of OsCPK11. GST- OsCPK11 was expressed in E. coli and used for an in vitro kinase assay. Biochemical analyses identified OsCPK11 as a CDPK. OsCPK11 autophosphorylated itself and transphosphorylated histone III-s and MBP as substrates in the presence of Ca<SUP>2+</SUP>. The activity of the recombinant OsCPK11 was influenced by Mg<SUP>2+</SUP>, with optimum activity detected at pH 7.0-7.5. OsCPK11 activity was not affected by Mg<SUP>2+</SUP>, Mn<SUP>2+</SUP>, or Na<SUP>+</SUP> in the presence of a high level of Ca<SUP>2+</SUP>. Autophosphorylation of OsCPK11 decreased Ca<SUP>2+</SUP> sensitivity of OsCPK11. An anti-OsCPK11 rabbit antibody recognized 95.5 kD of GST-OsCPK11, as shown by an immunoblot analysis. These results shed light on the function of OsCPK11 in Ca2<SUP>+</SUP>-mediated signaling in rice.