• Korean Journal of Microbiology
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• v.50 no.4
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• pp.275-280
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• 2014

Leucine-responsive Regulatory Protein (Lrp) from Escherichia coli is an 18.8 kDa protein composed of 164 amino acids. Wild type Lrp (Lrp Wt) does not possess any tryptophan amino acid which has strong intrinsic fluorescence, whereas the mutant Lrp R145W contains a single tryptophan at the position 145 in the leucine-responsive domain. To investigate the fluorescence character, the Lrp R145W and Lrp Wt proteins were purified. The fluorescence intensity of Lrp R145W is much higher than that of wild type protein, and the intensity of Lrp R145W was decreased by binding to its specific DNA designed from ilvIH operon and to L-leucine. In addition, the tryptophan fluorescence intensity of Lrp R145W was strongly quenched by addition of acrylamide even in the least amount of concentration as well as by urea. The data obtained from this study may give valuable information on the three dimensional structure of Lrp R145W.

• Korean Journal of Microbiology
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• v.46 no.1
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• pp.104-108
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• 2010

We describe the construction of derivatives of wild type and mutant lrp genes that encode 6XHis-tag Lrps. These derivatives of wild type and mutant Lrp could be useful for in vitro studies including Lrp conformational changes. We show that 6XHis-tag Lrp wild type and 6XHis-tag Lrp R145W bind with similar patterns in vitro to 21 bp duplex DNA containing the consensus sequences of Lrp sites of upstream of the ilvIH operon. In addition, we report here the 6XHis-tag Lrp R145W is useful to investigate the conformational changes of Lrp in solution by using its own intrinsic fluorescence characteristics.

• Reproductive and Developmental Biology
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• v.29 no.1
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• pp.19-24
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• 2005

The low density lipoprotein receptor-related protein 5 (LRP5) highly expressed in many tissues, including hepatocytes and pancreatic beta cells, can bind to apolipoprotein E. To evaluate in vivo roles of LRP5, we generated LRP5-deficient mice. LRP5 genomic DNA was isolated from TT2 embryonic stem (ES) cells. Targeting vector was constructed to disrupt an exon 18 of the mouse LRP5 gene and transfected into ES cells. Three homologous recombinants at LRP5 locus were identified from 178 G418-resistant clones. Chimeric males generated by morula aggregation technique were mated to C57BL/6 female mice. After achieving germ-line transmission, LRP5+/- females were crossed with LRP5+/- males to obtain LRP5-deficient mice. One line of mice lacking LRP5 gene was confirmed by Southern blotting. Such knock-out mice may serve as an effective animal model to study in vivo function of LRP5 gene.

• BMB Reports
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• v.41 no.3
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• pp.230-235
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• 2008

LRP15 is a novel gene cloned from lymphocytic cells, and its function is still unknown. Bioinformatic data showed that LRP15 might be regulated by DNA methylation and had an important role in DNA repair. In this study, we investigate whether the expression of LRP15 is regulated by DNA methylation, and whether overexpression of LRP15 increases efficiency of DNA repair of UV-induced DNA damage in HeLa cells. The results showed (1) the promoter of LRP15 was hypermethylated in HeLa cells, resulting a silence of its expression. Gene expression was restored by a demethylating agent, 5-aza-2'-deoxycytidine, but not by a histone deacetylase inhibitor, trichostatin A; (2) overexpression of LRP15 inhibited HeLa cell proliferation, and the numbers of cells in the G2/M phase of the cell cycle in cells transfected with LRP15 increased about 10% compared with controls; (3) cyclin B1 level was much lower in cells overexpressing LRP15 than in control cells; and (4) after exposure to UV radiation, the LRP15-positive cells showed shorter comet tails compared with the LRP15-negative cells. From these results we conclude that the expression of LRP15 is controlled by methylation in its promoter in HeLa cells, and LRP15 confers resistance to UV damage and accelerates the DNA repair rate.

• Korean Journal of Microbiology
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• v.53 no.4
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• pp.297-303
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• 2017

Leucine-responsive regulatory protein (LRP) is a regulatory protein of molecular weight 18.8 kDa and is widely known to regulate many metabolic and functional activities of operons in Escherichia coli. The gene for Lrp from Escherichia coli in pQE system of 6 ${\times}$ His-tagging was expressed and $^3H$-labeled protein, as well as the wild type Lrp, was purified. The crosslink experiments were performed to analyze the quaternary structure of Lrp at high of $5{\mu}M$ and at low concentrations below $0.3{\mu}M$ with cross linkers, such as glutaraldehyde, 1, 2, 3, 4-diepoxy-butane (DEB), and ethylene glycol bis (succinimidyl succinate) (EGS). In the experiments, we found that the Lrp protein can be formed higher conformation states of tetramer, hexamer, octamer, as well as dimeric state when incubated with the above cross linkers.

• Korean Journal of Microbiology
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• v.42 no.4
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• pp.239-245
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• 2006

Leucine-responsive Regulatory Protein (Lrp) is a global regulator involved in modulating a variety of metabolic functions, including the catabolism and anabolism of amino acids as well as pili synthesis. In addition, there is growing evidences that Lrp may play an important role when cells make transition between rich and lean nutritional conditions. In this review, the biochemical characteristics of Lrp are described to provide a good example that shows how bacteria adapt to nutrient limitation and environmental stress.

• Journal of Microbiology and Biotechnology
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• v.18 no.11
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• pp.1755-1761
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• 2008

The present study revealed that Lrp, a leucine-responsive regulatory protein, is involved in the regulation of cadBA transcription through activation of $P_{cadBA}$. The influence of Lrp on $P_{cadBA}$ was mediated by CadC, and thereby, CadC was able to compensate for the lack of Lrp in the activation of $P_{cadBA}$. Western blot analyses and EMSA demonstrated that the cellular level of CadC was not significantly affected by Lrp, and that Lrp exerted its effect by directly binding to $P_{cadBA}$. These combined results suggested that CadC and Lrp function cooperatively to activate the $P_{cadBA}$ rather than sequentially in a regulatory cascade.

• Parasites, Hosts and Diseases
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• v.59 no.1
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• pp.77-82
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• 2021

As malaria remains a major health problem worldwide, various diagnostic tests have been developed, including microscopy-based and rapid diagnostic tests. LabChip real-time PCR (LRP) is a small and portable device used to diagnose malaria using lab-on-a-chip technology. This study aimed to evaluate the diagnostic performance of LRP for detecting malaria parasites. Two hundred thirteen patients and 150 healthy individuals were enrolled from May 2009 to October 2015. A diagnostic detectability of LRP for malaria parasites was compared to that of conventional RT-PCR. Sensitivity of LRP for Plasmodium vivax, P. falciparum, P. malariae, and P. ovale was 95.5%, 96.0%, 100%, and 100%, respectively. Specificity of LRP for P. vivax, P. falciparum, P. malariae, and P. ovale was 100%, 99.3%, 100%, and 100%, respectively. Cohen's Kappa coefficients between LRP and CFX96 for detecting P. vivax, P. falciparum, P. malariae, and P. ovale were 0.96, 0.98, 1.00, and 1.00, respectively. Significant difference was not observed between the results of LRP and conventional RT-PCR and microscopic examination. A time required to amplify DNAs using LRP and conventional RT-PCR was 27 min and 86 min, respectively. LRP amplified DNAs 2 times more fast than conventional RT-PCR due to the faster heat transfer. Therefore, LRP could be employed as a useful tool for detecting malaria parasites in clinical laboratories.

• Proceedings of the KSAR Conference
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• 2002.06a
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• pp.82-82
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• 2002

The Wnt signaling pathway plays pivotal roles in embryonic development and oncogenesis through various signaling molecules inculding Frizzled receptor, recently characterized LRP5/6 and Dickkopf protein. Although Wnt signaling has been characterized in both developmental and oncogenic processes, little is known about its function in the normal adult. The ability of LRP5 to bind apolipoprotein E(apoE) and the abundant expression of LRP5 transcripts in hepatocytes, raise the possibility that LRP5 plays a role in the hepatic clearance of ApoE-containing chylomicron remonants, a major plasma lipoprotein carrying diet-derived cholesterol. (omitted)

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.15
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• pp.6663-6668
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• 2015

Background: Treatment failure in leukemia is due to either pharmacokinetic resistance or cell resistance to drugs. Materials and Methods: Gene expression of multiple drug resistance protein (MDR-1), multidrug resistance-related protein (MRP) and low resistance protein (LRP) was assessed in 45 pediatric ALL cases and 7 healthy controls by real time PCR. The expression was scored as negative, weak, moderate and strong. Results: The male female ratio of cases was 2.75:1 and the mean age was 5.2 years. Some 26/45 (58%) were in standard risk, 17/45(38%) intermediate and 2/45 (4%) in high risk categorie, 42/45 (93%) being B-ALL and recurrent translocations being noted in 5/45 (11.0%). Rapid early response (RER) at day 14 was seen in 37/45 (82.3%) and slow early response (SER) in 8/45 (17.7%) cases. Positive expression of MDR-1, LRP and MRP was noted in 14/45 (31%), 15/45 (33%) and 27/45 (60%) cases and strong expression in 3/14 (21%), 11/27 (40.7%) and 8/15 (53.3%) cases respectively. Dual or more gene positivity was noted in 17/45 (38%) cases. 46.5 % (7/15) of LRP positive cases at day 14 were in RER as compared to 100% (30/30) of LRP negative cases (p<0.05). All 8 (100%) LRP positive cases in SER had strong LRP expression (p=<0.05). Moreover, only 53.3% of LRP positive cases were in haematological remission at day 30 as compared to 100% of LRP negative cases (p=<0.05). Conclusions: Our study indicated that increased LRP expression at diagnosis in pediatric ALL predicts poor response to early treatment and hence can be used as a prognostic marker. However, larger prospective studies with longer follow up are needed, to understand the clinical relevance of drug resistance proteins.