• Journal of Yeungnam Medical Science
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• 제9권2호
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• pp.248-255
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• 1992

S. typhimurium의 세포내생존을 가능케하는 유전자가 다른 세균에서도 존재하는지를 조사하기 위해 8주의 세균주를 사용하였다. phoP-PhoQ operon은 세포내 환경의 자극을 인지하고 그 환경의 적응에 관여하는 유전자의 유전자표현을 조절한다고 알려져 있다. S. typhimurium의 phoP region의 514 basepairs EcoRV DNA fragment를 probe로 dot blot hybridization을 실시하였다. K. pneumoniae, P. aeruginosa, S. marscescens, E. cloacae, S. typhimurium의 phoP/phoQ gene과 유사한 DNA sequence를 가지지 않았으며 E. coli, S. dysenteriae, E. cloacae에서는 세포내 생존가능세균이 아님에도 불구하고 positive signal을 나타내었다. 이상의 결과에서 S. typhimurium외의 세포내 생존가능세균에는 phoP/PhoQ operon이 없다는 것을 알게 되었고 세포내 생존이 가능하지는 않지만 S. typhimurium과 계통발생학적으로 가까운 세균주에서 phoP/phoQ operon이 발견되었다. L. monocytogenes의 세포내 생존에는 phoP/phoQ에 의존하지 않는 어떤 다론 기전이 존재할 것으로 사료된다.

• Journal of Microbiology and Biotechnology
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• 제33권9호
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• pp.1130-1140
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• 2023

Among the AAA+ proteases in bacteria, FtsH is a membrane-bound ATP-dependent metalloprotease, which is known to degrade many membrane proteins as well as some cytoplasmic proteins. In the intracellular pathogen Salmonella enterica serovar Typhimurium, FtsH is responsible for the proteolysis of several proteins including MgtC virulence factor and MgtA/MgtB Mg²⁺ transporters, the transcription of which is controlled by the PhoP/PhoQ two-component regulatory system. Given that PhoP response regulator itself is a cytoplasmic protein and also degraded by the cytoplasmic ClpAP protease, it seems unlikely that FtsH affects PhoP protein levels. Here we report an unexpected role of the FtsH protease protecting PhoP proteolysis from cytoplasmic ClpAP protease. In FtsH-depleted condition, PhoP protein levels decrease by ClpAP proteolysis, lowering protein levels of PhoP-controlled genes. This suggests that FtsH is required for normal activation of PhoP transcription factor. FtsH does not degrade PhoP protein but directly binds to PhoP, thus sequestering PhoP from ClpAP-mediated proteolysis. FtsH's protective effect on PhoP can be overcome by providing excess ClpP. Because PhoP is required for Salmonella's survival inside macrophages and mouse virulence, these data implicate that FtsH's sequestration of PhoP from ClpAP-mediated proteolysis is a mechanism ensuring the amount of PhoP protein during Salmonella infection.

• Journal of Microbiology and Biotechnology
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• 제26권9호
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• pp.1620-1628
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• 2016

In this study, we investigated colistin resistance mechanisms associated with the regulation of the pbgP operon in Klebsiella pneumoniae, using four isogenic pairs of colistin-susceptible strains and their colistin-resistant derivatives and two colistin-resistant clinical isolates. Amino acid sequence alterations of PhoPQ, PmrAB, and MgrB were investigated, and mRNA expression levels of phoQ, pmrB, pmrD, and pbgP were measured using quantitative real-time PCR. The phoQ and pmrB genes were deleted from two colistin-resistant derivatives, 134R and 063R. We found that phoQ, pmrD, and pbgP were significantly upregulated in all colistin-resistant derivatives. However, pmrB was significantly upregulated in only two colistin-resistant derivatives and one clinical strain. pmrB was not overexpressed in the other strains. The minimum inhibitory concentration of colistin was drastically lower in both phoQ- and pmrB-deleted mutants from a colistin-resistant derivative (134R) that was overexpressing phoQ and pmrB. However, colistin susceptibility was restored only in a phoQ-deleted mutant from a colistin-resistant derivative (063R) without overexpression of pmrB. In conclusion, two different regulations of the pbgP operon may associate with the development of colistinresisant K. pneumoniae.

• Journal of Yeungnam Medical Science
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• 제12권2호
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• pp.237-245
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• 1995

Klebsiella pneumoniae 의 phoA 유전자를 함유하는 DNA를 plasmid pACYC184에 클로닝 하였다. 클로닝된 DNA의 크기는 4.0 kb이었으며 제한효소지도를 작성한 결과 3개의 PstI 절단부위와 4개의 PvuII 절단부위가 발견되었다. Klebsiella pneumoniae 의 phoA 유전자의 염기서열은 Escherichia coli와 매우 유사하여 80%의 유사성을 보였으며 이는 이 두 균종이 서로 유전적으로 매우 가까운 관계에 있음을 시사하였다.

• Journal of Microbiology
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• 제43권spc1호
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• pp.85-92
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• 2005

An early step in the pathogenesis of non-typhoidal Salmonella species is the ability to penetrate the intestinal epithelial monolayer. This process of cell invasion requires the production and transport of secreted effector proteins by a type III secretion apparatus encoded in Salmonella pathogenicity island I (SPI-1). The control of invasion involves a number of genetic regulators and environmental stimuli in complex relationships. SPI-1 itself encodes several transcriptional regulators (HilA, HilD, HilC, and InvF) with overlapping sets of target genes. These regulators are, in turn, controlled by both positive and regulators outside SPI-1, including the two-component regulators BarA/SirA and PhoP/Q, and the csr post-transcriptional control system. Additionally, several environmental conditions are known to regulate invasion, including pH, osmolarity, oxygen tension, bile, $Mg^{2+}$ concentration, and short chain fatty acids. This review will discuss the current understanding of invasion control, with emphasis on the interaction of environmental factors with genetic regulators that leads to productive infection.

• 한국초지조사료학회지
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• 제13권3호
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• pp.177-183
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• 1993

Agronacterium tumefaciens(strain LBA4404)를 매개로 한 외래 유전자의 식물체로의 도입에 관한 실험을 하여 아래와 가은 결과를 얻었다. 모델 식물로는 담배(Nivotuana tabacum c.v. samsun)를 사용하였으며, 외래 유전자는 효모 유래의 Acid phosphatase 유전자인 PH05를 사용하였다. pVC727G에서 PH05를 잘라내어 전기영동 및 graphical estimation법으로 확인한 결과, PH05의 크기는 1.5kb였다. pVC727G와 광역plasmid인 qBI121을 이용하여 식물체 형질전환을 위한 vector인 pBKJ I을 만들었다. pBKJ I을 Agronacterium LBA4404에 subcloninggksgn 담배의 leaf dise를 Agronacterium LBA4404과 공배양하여 형질전환을 유도하였다. kanamycindmf 첨가한 MS-n/B음지에서 형질전환된 shoots를 얻었으며, 이들의 재분화를 실시하여 형질전환된 식물체를 얻었다. 형질전환된 식물체의 genomic DNA를 PH05로서 southern hybridization하여 형질전환을 확인하였으며, 식물체의 잎, 줄기 및 뿌리의 Apase(PH05)활성을 측정하여 도입한 PH05가 발현됨을 확인하였다.