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Lynn Heo(Lynn Heo),Yongmin Cho(Yongmin Cho),Junhyeok Choi(Junhyeok Choi),Jeongwook Lee(Jeongwook Lee),Yoobin Han(Yoobin Han),Sang-Wook Han(Sang-Wook Han) 한국식물병리학회 2023 Plant Pathology Journal Vol.39 No.3
Acidovorax citrulli (Ac) is a phytopathogenic bacterium that causes bacterial fruit blotch (BFB) in cucurbit crops, including watermelon. However, there are no effective methods to control this disease. YggS family pyridoxal phosphate-dependent enzyme acts as a coen-zyme in all transamination reactions, but its function in Ac is poorly understood. Therefore, this study uses proteomic and phenotypic analyses to characterize the functions. The Ac strain lacking the YggS family pyri-doxal phosphate-dependent enzyme, AcΔyppAc(EV), virulence was wholly eradicated in geminated seed inoculation and leaf infiltration. AcΔyppAc(EV) propa-gation was inhibited when exposed to L-homoserine but not pyridoxine. Wild-type and mutant growth were comparable in the liquid media but not in the solid media in the minimal condition. The comparative proteomic analysis revealed that YppAc is primarily involved in cell motility and wall/membrane/envelop biogenesis. In addition, AcΔyppAc(EV) reduced biofilm formation and twitching halo production, indicating that YppAc is involved in various cellular mechanisms and possesses pleiotropic effects. Therefore, this identi-fied protein is a potential target for developing an effi-cient anti-virulence reagent to control BFB.
Jongchan Lee,Lynn Heo,Sang-Wook Han 한국식물병리학회 2021 Plant Pathology Journal Vol.37 No.6
Acidovorax citrulli (Ac) is the causative agent of bacte- rial fruit blotch disease in watermelon. Since resistant cultivars have not yet been developed, the virulence factors/mechanisms of Ac need to be characterized. This study reports the functions of a putative pyridoxal phosphate-dependent aminotransferase (PpdaAc) that transfers amino groups to its substrates and uses pyridoxal phosphate as a coenzyme. It was observed that a ppdaAc knockout mutant had a significantly reduced virulence in watermelon when introduced via germinated-seed inoculation as well as leaf infiltration. Comparative proteomic analysis predicted the cellular mechanisms related to PpdaAc. Apart from causing virulence, the PpdaAc may have significant roles in energy production, cell membrane, motility, chemo- taxis, post-translational modifications, and iron-related mechanisms. Therefore, it is postulated that PpdaAc may possess pleiotropic effects. These results provide new insights into the functions of a previously unidenti- fied PpdaAc in Ac.
Minyoung Kim,Jongchan Lee,Lynn Heo,Sang Jun Lee,Sang-Wook Han 한국식물병리학회 2021 Plant Pathology Journal Vol.37 No.1
Acidovorax citrulli (Ac) is the causal agent of bacterial fruit blotch (BFB) in watermelon, a disease that poses a serious threat to watermelon production. Because of the lack of resistant cultivars against BFB, virulence factors or mechanisms need to be elucidated to control the disease. Glycerol-3-phosphate dehydrogenase is the enzyme involved in glycerol production from glucose during glycolysis. In this study, we report the functions of a putative glycerol-3-phosphate dehydrogenase in Ac (GlpdAc) using comparative proteomic analysis and phenotypic observation. A glpdAc knockout mutant, AcΔglpdAc(EV), lost virulence against watermelon in two pathogenicity tests. The putative 3D structure and amino acid sequence of GlpdAc showed high similarity with glycerol-3-phosphate dehydrogenases from other bacteria. Comparative proteomic analysis revealed that many proteins related to various metabolic pathways, including carbohydrate metabolism, were affected by GlpdAc. Although AcΔglpdAc(EV) could not use glu- cose as a sole carbon source, it showed growth in the presence of glycerol, indicating that GlpdAc is involved in glycolysis. AcΔglpdAc(EV) also displayed higher cell- to-cell aggregation than the wild-type bacteria, and tol- erance to osmotic stress and ciprofloxacin was reduced and enhanced in the mutant, respectively. These results indicate that GlpdAc is involved in glycerol metabolism and other mechanisms, including virulence, demon- strating that the protein has pleiotropic effects. Our study expands the understanding of the functions of proteins associated with virulence in Ac.
이상훈(Sanghoon Lee),허환조(Hwanjo Heo),김효곤(Hyogon Kim),최린(Lynn Choi) 한국정보과학회 2003 한국정보과학회 학술발표논문집 Vol.30 No.2Ⅰ
바이러스로 시작된 악성 코드는 웜이라는 형태로 발전하였다. 인터넷 망의 고속화와 확장에 의해 웜의 전파 속도와 감염 범위는 증가하였지만, 아직까지 웜을 차단할 수 있는 획기적인 방법은 개발되지 않았고, 웜에 의한 피해는 갈수록 치명적인 결과를 낳고 있다. 본고에서는 Bloom Filter[t]를 이용한 content filtering 방법을 제안한다. 실험을 통해, 이미 알려진 웜에 대한 Bloom Filter의 성능을 검증하였으며, 알려지지 않은 웜에 대한 Bloom Filter의 적용 방법도 제안한다.