• Journal of Yeungnam Medical Science
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• v.9 no.2
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• pp.248-255
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• 1992

Eight bacterial strains were examined whether they have phoP/phoQ genes which were known to be involved in the intracellular survival of Salmonella typhimurium. The phoP/phoQ operon were known to sense the stimuli of the genes involved in the adaptation of the environment. Using 514-basepairs EcoRV DNA fragment of phoP region of Salmonella typhimurium as a probe, dot blot hybridization were performed. Chromosomal DNAs of Klebsiella pneumoniae, Pseudomonas aeruginosa, Serratia marscescens, Enterobacter cloacae, Salmonella typhimurium, Escherichia coli, Shigella dysenteriae, and Listeria monocytogenes were examined by DNA hybridization assay. Against our expectation, intracellular pathogen, L. monocytogenes, did not have similar DNA sequences to phoP/phoQ of S. typhimurium, while E. coli, S. dysenteriae, and E. cloacae showed the positive signal even though they were not intracellular pathogens. This result suggested that the phoP/PhoQ operon was absent in intracellular pathogenic bacterias other than S. typhimurium. Rather it was found in phylogenetically closer bacterias to S. typhimurium, which were not able to survive in intracellular environment. Some different mechanism, which is not dependent on phoP/PhoQ operon, could be involved in the intracelluar survival of L. monocytogenes.

• Journal of Microbiology and Biotechnology
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• v.33 no.9
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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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• v.26 no.9
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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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• v.12 no.2
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• pp.237-245
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• 1995

The DNA fragment containing the phoA of Klebsiella pneumoniae was cloned into pACYC184. The size of the insert was 4.0 kb and the restriction map showed it contained 3 PstI sites and 4 PvuII sites. The nucleotide sequence of the phoA region was determined, which showed strong (80 %) sequence similarity with that of Escherichia coli. This suggested that these two species are phylogenetically very close to each other.

• Journal of Microbiology
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• v.43 no.spc1
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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.

• Journal of The Korean Society of Grassland and Forage Science
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• v.13 no.3
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• pp.177-183
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• 1993

This study was conducted to obtain the transformed tobacco plants with S. cerevisiae Acid phosphatase gene(PH05) using Agrobacterium tumefaciens and th confirm plant transformation and gene expression. the results obtained were summarized as follows: APase activity of Saccharomyces cereviase NA 87-11A was remarkably showed up as deep red color when assayed by Tohe and Oshima(1974). PH05 fragment, Apase gene, was obtained from pVC727G and the graphically estimated size was about 1.5kb by agarose gel electrophoresis. The sequencing results of 5'end and 3'end of PH05 using dideoxy chain termination method were coinsided with the full length nucleotide already. pBKJ I vector was constructed by isolation of PH05 fragment from pVC727-1 and pBKSI-1 digesred with Sma I and Xba I. Isolated plasmid from transformed A. tumefaciens with constructed pBKJ I when it was electrophoresed with agarose gel. The dosc of tobacco leaf was cocultivated 재소 transformed Agronacterium tumefaciens. Transformed shoots were selected on kanamtcin-containing MS-n/B medium and they were regenerated. The transgenic tobacco plants were elucidated by isolation of genomic DNA and genomic southern hybridization using ${\alpha}-^{32}P$ labelled PH05 fragments. The PH05 in transformed tobacco plants was expressed in leaf, stem and root, and its APase activity was estimated as deep red color by Tohe method.