• Proceedings of the Korean Society of Life Science Conference
• /
• 2008.10a
• /
• pp.73.2-73.2
• /
• 2008

• Journal of Microbiology and Biotechnology
• /
• v.24 no.12
• /
• pp.1609-1621
• /
• 2014

The plant pathogen Burkholderia gladioli, which has a broad host range that includes rice and onion, causes bacterial panicle blight and sheath rot. Based on the complete genome sequence of B. gladioli BSR3 isolated from infected rice sheaths, the genome of B. gladioli BSR3 contains the luxI/luxR family of genes. Members of this family encode N-acyl-homoserine lactone (AHL) quorum sensing (QS) signal synthase and the LuxR-family AHL signal receptor, which are similar to B. glumae BGR1. In B. glumae, QS has been shown to play pivotal roles in many bacterial behaviors. In this study, we compared the QS-dependent gene expression between B. gladioli BSR3 and a QS-defective B. gladioli BSR3 mutant in two different culture states (10 and 24 h after incubation, corresponding to an exponential phase and a stationary phase) using RNA sequencing (RNA-seq). RNA-seq analyses including gene ontology and pathway enrichment revealed that the B. gladioli BSR3 QS system regulates genes related to motility, toxin production, and oxalogenesis, which were previously reported in B. glumae. Moreover, the uncharacterized polyketide biosynthesis is activated by QS, which was not detected in B. glumae. Thus, we observed not only common QS-dependent genes between B. glumae BGR1 and B. gladioli BSR3, but also unique QS-dependent genes in B. gladioli BSR3.

• Molecules and Cells
• /
• v.28 no.5
• /
• pp.447-453
• /
• 2009

The quorum sensing (QS) inhibitors that antagonize TraR, a receptor protein for N-3-oxo-octanoyl-L-homoserine lactones (3-oxo-C8-HSL), a QS signal of Agrobacterium tumefaciens were developed. The structural analogues of 3-oxo-C8-HSL were designed by in silico molecular modeling using SYBYL packages, and synthesized by the solid phase organic synthesis (SPOS) method, where the carboxamide bond of 3-oxo-C8-HSL was replaced with a nicotinamide or a sulfonamide bond to make derivatives of N-nicotinyl-L-homoserine lactones or N-sulfonyl-L-homoserine lactones. The in vivo inhibitory activities of these compounds against QS signaling were assayed using reporter systems and compared with the estimated binding energies from the modeling study. This comparison showed fairly good correlation, suggesting that the in silico interpretation of ligand-receptor structures can be a valuable tool for the pre-design of better competitive inhibitors. In addition, these inhibitors also showed anti-biofilm activities against Pseudomonas aeruginosa.

• Journal of Microbiology and Biotechnology
• /
• v.27 no.12
• /
• pp.2104-2111
• /
• 2017

A new series comprising phenylacetyl-homoserine lactones (HSLs), caffeoyl-HSL and feruloyl-HSL, was biologically synthesized using an artificial de novo biosynthetic pathway. We developed an Escherichia coli system containing artificial biosynthetic pathways that yield phenylacetyl-HSLs from simple carbon sources. These artificial biosynthetic pathways contained the LuxI-type synthase gene (rpaI) in addition to caffeoyl-CoA and feruloyl-CoA biosynthetic genes, respectively. Finally, the yields for caffeoyl-HSL and feruloyl-HSL were $97.1{\pm}10.3$ and $65.2{\pm}5.7mg/l$, respectively, by tyrosine-overproducing E. coli with a $\text\tiny{L}$-methionine feeding strategy. In a quorum sensing (QS) competition assay, feruloyl-HSL and p-coumaroyl-HSL antagonized the QS receptor TraR in Agrobacterium tumefaciens NT1, whereas caffeoyl-HSL did not.

• Microbiology and Biotechnology Letters
• /
• v.50 no.1
• /
• pp.1-14
• /
• 2022

Bacteria communicate with each other through an intricate communication mechanism known as quorum sensing (QS). QS regulates different behavioral aspects in bacteria, such as biofilm formation, sporulation, virulence gene expression, antibiotic production, and bioluminescence. Several different chemical signals and signal detection systems play vital roles in promoting highly efficient intra- and interspecies communication. Gram-negative bacteria coordinate gene regulation through the production of acyl homoserine lactones (AHLs). Gram-positive bacteria do not code for AHL production, while some gram-negative bacteria have an incomplete AHL-QS system. Despite this fact, these microbes can detect AHLs owing to the presence of LuxR solo receptors. Various studies have reported the role of AHLs in interspecies signaling. Moreover, as bacteria live in a polymicrobial community, the production of extracellular compounds to compete for resources is imperative. Thus, AHL-mediated signaling and inhibition are considered to affect virulence in bacteria. In the current review, we focus on the synthesis and regulation mechanisms of AHLs and highlight their role in interspecies bacterial signaling. Exploring interspecies bacterial signaling will further help us understand host-pathogen interactions, thereby contributing to the development of therapeutic strategies intended to target chronic polymicrobial infections.

• Journal of Microbiology and Biotechnology
• /
• v.19 no.5
• /
• pp.431-438
• /
• 2009

The alkaline serine protease asp, which was shown to be a virulence factor of Vibrio alginolyticus as a purified protein, was cloned from V. alginolyticus EPGS, a strain recently isolated from moribund Epinephelus coioides in an outbreak of vibriosis in a mariculture farm of Shenzhen. The asp null mutant was constructed by homologous recombination with suicide plasmid pNQ705-1. Compared with the wild-type strain, the asp null mutant exhibited a significant decrease of total extracellular protease activity, and caused a IS-fold decrease in virulence of V. alginolyticus. In our previous study, the luxO and $luxR_{val}$ genes from V. alginolyticus MVP01 were cloned and identified, and the luxO-$luxR_{val}$ regulatory couple was shown to regulate various genes expression, suggesting that it played a central role in the quorum sensing system of V. alginolyticus. In this study, the regulation of the asp gene was analyzed by using RT-PCR and quantitative real-time PCR methods; we proved that its transcription was greatly induced at the late stage of growth and was regulated by a luxO-$luxR_{val}$ regulatory system.

• Proceedings of the Microbiological Society of Korea Conference
• /
• 2005.05a
• /
• pp.210.1-210
• /
• 2005

• 한국생물공학회:학술대회논문집
• /
• 2005.10a
• /
• pp.635-636
• /
• 2005

• Proceedings of the Korean Society for Applied Microbiology Conference
• /
• 2001.06a
• /
• pp.9-14
• /
• 2001

• Proceedings of the Korean Information Science Society Conference
• /
• 2003.04a
• /
• pp.656-658
• /
• 2003

무선 인터넷 망의 구축과 휴대용 정보기기의 일반 보급으로 이동형 정보 환경이 최근 급속히 확산되고 있다. 본 논문은 이동형 환경에서의 거래 안정성과 데이터 가용성 증대를 위한 새로운 복제 데이터 관리 기법을 제안한다. 제안된 위임 정족수 합의(Proxy Quorum Consensus) 모델은 불안정한 상태의 다수의 모바일 사이트에 직접적인 투표를 하지 않는 대신에, 미리 선출한 대표 정족 집단에 위임함으로써, 안정된 위임 투표(Proxy Voting)를 진행하는 제어 기법이다. 이 기법을 통하여 통신 비용 절감 및 응답 속도 향상 등의 효과를 기대할 수 있다.