• BMB Reports
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• v.33 no.6
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• pp.448-453
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• 2000

In yeast the key gluconeogenic enzyme, fructose-1,6-bisphosphatase (FBPase), is selectively targeted from the cytosol to the lysosome (vacuole) for degradation when glucose starved cells are replenished with glucose. The pathway for glucose induced FBPase degradation is unknown. To identify the receptor-mediated degradation pathway of FBPase, we investigated the presence of the FBPase receptor on the vacuolar membrane by cell fractionation experiments and binding assay using vid mutant (vacuolar import and degradation), which is defective in the glucose-induced degradation of FBPase. FBPase sedimented in the pellets from vid24-1 mutant after centrifugation at $15,000{\times}g$ for 15 min, suggesting that FBPase is associated with subcellular structures. Cell fractionation experiments revealed that FBPase is preferentially associated with the vacuole, but not with other organelles in vid24-1. FBPase enriched fractions that cofractionated with the vacuole were sensitive to proteinase K digestion, indicating that FBPase is peripherally associated with the vacuole. We developed an assay for the binding of FBPase to the vacuole. The assay revealed that FBPase bound to the vacuole with a Kd of $2.3{\times}10^6M$. The binding was saturable and specific. These results suggest that a receptor for FBPase degradation exists on the vacuolar membrane. It implies the existence of the receptor-mediated degradation pathway of FBPase by the lysosome.

• BMB Reports
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• v.51 no.3
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• pp.143-150
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• 2018

The Hippo signaling pathway plays an essential role in adult tissue homeostasis and organ size control. Abnormal regulation of Hippo signaling can be a cause for multiple types of human cancers. Since the awareness of the importance of the Hippo signaling in a wide range of biological fields has been continually grown, it is also understood that a thorough and well-rounded comprehension of the precise dynamics could provide fundamental insights for therapeutic applications. Several components in the Hippo signaling pathway are known to be targeted for proteasomal degradation via ubiquitination by E3 ligases. ${\beta}-TrCP$ is a well-known E3 ligase of YAP/TAZ, which leads to the reduction of YAP/TAZ levels. The Hippo signaling pathway can also be inhibited by the E3 ligases (such as ITCH) which target LATS1/2 for degradation. Regulation via ubiquitination involves not only complex network of E3 ligases but also deubiquitinating enzymes (DUBs), which remove ubiquitin from its targets. Interestingly, non-degradative ubiquitin modifications are also known to play important roles in the regulation of Hippo signaling. Although there has been much advanced progress in the investigation of ubiquitin modifications acting as regulators of the Hippo signaling pathway, research done to date still remains inadequate due to the sheer complexity and diversity of the subject. Herein, we review and discuss recent developments that implicate ubiquitin-mediated regulatory mechanisms at multiple steps of the Hippo signaling pathway.

• Journal of Microbiology and Biotechnology
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• v.23 no.11
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• pp.1610-1616
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• 2013

Endosulfan is a chlorinated pesticide; its persistence in the environment and toxic effects on biota are demanding its removal. This study aims at improving the tolerance of the previously isolated fungus Aspergillus niger (A. niger) ARIFCC 1053 to endosulfan. Released chloride, dehalogenase activity, and released proteins were estimated along with analysis of endosulfan degradation and pathway identification. The culture could tolerate 1,000 mg/ml of technical grade endosulfan. Complete disappearance of endosulfan was seen after 168 h of incubation. The degradation study could easily be correlated with increase in released chlorides, dehalogenase activity and protein released. Comparative infrared spectral analysis suggested that the molecule of endosulfan was degraded efficiently by A. niger ARIFCC 1053. Obtained mass ion values by GC-MS suggested a hypothetical pathway during endosulfan degradation by A. niger ARIFCC 1053. All these results provide a basis for the development of bioremediation strategies to remediate the pollutant under study in the environment.

• Journal of Microbiology and Biotechnology
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• v.14 no.3
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• pp.483-489
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• 2004

Pseudomonas sp. S-47 is a bacterium capable of degrading benzoate as well as 4-chlorobenzoate (4CBA). Benzoate and 4CBA are known to be degraded via a meta-cleavage pathway characterized by a series of enzymes encoded by xyl genes. The meta-cleavage pathway operon in Pseudomonas sp. S-47 encodes a set of enzymes which transform benzoate and 4CBA into TCA cycle intermediates via the meta-cleavage of (4-chloro )catechol to produce pyruvate and acetyl-CoA. In the current study, the meta-pathway gene cluster was cloned from the chromosomal DNA of S-47 strain to obtain pCS1, which included the degradation activities for 4CBA and catechol. The genetic organization of the operon was then examined by cloning the meta-pathway genes into a pBluescript SKII(+) vector. As such, the meta-pathway operon from Pseudomonas sp. S-47 was found to contain 13 genes in the order of xylXYZLTEGFlQKIH. The two regulatory genes, xylS and xylR, that control the expression of the meta-pathway operon, were located adjacently downstream of the meta-pathway operon. The xyl genes from strain S-47 exhibited a high nucleoside sequence homology to those from Pseudomonas putida mt-2, except for the xylJQK genes, which were more homologous to the corresponding three genes from P. stutzeri AN10. One open reading frame was found between the xylH and xylS genes, which may playa role of a transposase. Accordingly, the current results suggest that the xyl gene cluster in Pseudomonas sp. S-47 responsible for the complete degradation of benzoate was recombined with the corresponding genes from P. putida mt-2 and P. stutzeri AN10.

• Journal of Microbiology and Biotechnology
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• v.19 no.11
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• pp.1439-1446
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• 2009

Isocarbophos is a widely used organophosphorus insecticide that has caused environmental pollution in many areas. However, degradation of isocarbophos by pure cultures has not been extensively studied, and the degradation pathway has not been determined. In this paper, a highly effective isocarbophos-degrading strain, scl-2, was isolated from isocarbophos-polluted soil. The strain scl-2 was preliminarily identified as Arthrobacter sp. based on its morphological, physiological, and biochemical properties, as well as 16S rDNA analysis. The strain scl-2 could utilize isocarbophos as its sole source of carbon and phosphorus for growth. One hundred mg/l isocarbophos could be degraded to a non detectable level in 18 h by scl-2 in cell culture, and isofenphos-methyl, profenofos, and phosmet could also be degraded. During the degradation of isocarbophos, the metabolites isopropyl salicylate, salicylate, and gentisate were detected and identified based on MS/MS analysis and their retention times in HPLC. Transformation of gentisate to pyruvate and fumarate via maleylpyruvate and fumarylpyruvate was detected by assaying for the activities of gentisate 1,2-dioxygenase (GDO) and maleylpyruvate isomerase. Therefore, we have identified the degradation pathway of isocarbophos in Arthrobacter sp. scl-2 for the first time. This study highlights an important potential use of the strain scl-2 for the cleanup of environmental contamination by isocarbophos and presents a mechanism of isocarbophos metabolism.

• Journal of Microbiology and Biotechnology
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• v.16 no.3
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• pp.391-398
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• 2006

$NF-{\kappa}B$ is a transcription factor involved in the innate immunity against bacterial infection and inflammation. It is also known to render cells resistant to the apoptosis caused by some anticancer drugs. Such a chemoresistance of cancer cells may be related to the activation of $NF-{\kappa}B$ transcription factor; however, the mechanism of activation is not well understood. Here, we demonstrate that a chemotherapeutic agent, etoposide, independently stimulates the $I{\kappa}B{\alpha}$ degradation pathway and PI3-kinase/Akt signaling pathway: The classical $I{\kappa}B{\alpha}$ degradation pathway leads to the nuclear translocation and DNA binding of p65 subunit through $IKK{\beta}$ kinase, whereas the PI3-kinase/Akt pathway plays a distinct role in activating this transcription factor. The PI3-kinase/Akt pathway acts on the p50 subunit of the $NF-{\kappa}B$ transcription factor and enhances the DNA binding affinity of the p50 protein. It may also explain the role of the PI3-kinase/Akt pathway in the anti-apoptotic function of $NF-{\kappa}B$ during chemoresistance of cancer cells.

• Journal of Microbiology and Biotechnology
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• v.26 no.11
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• pp.1943-1950
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• 2016

Polycyclic aromatic hydrocarbons (PAHs) are commonly present xenobiotics in natural and contaminated soils. We studied three (phenanthrene, naphthalene, and biphenyl) xenobiotics, catabolism, and associated proteins in Sphingobium chungbukense DJ77 by two-dimensional gel electrophoresis (2-DE) analysis. Comparative analysis of the growth-dependent 2-DE results revealed that the intensity of 10 protein spots changed identically upon exposure to the three xenobiotics. Among the upregulated proteins, five protein spots, which were putative dehydrogenase, dioxygenase, and hydrolase and involved in the catabolic pathway of xenobiotic degradation, were induced. Identification of these major multifunctional proteins allowed us to map the multiple catabolic pathway for phenanthrene, naphthalene, and biphenyl degradation. A part of the initial diverse catabolism was converged into the catechol degradation branch. Detection of intermediates from 2,3-dihydroxy-biphenyl degradation to pyruvate and acetyl-CoA production by LC/MS analysis showed that ring-cleavage products of PAHs entered the tricarboxylic acid cycle, and were mineralized in S. chungbukense DJ77. These results suggest that S. chungbukense DJ77 completely degrades a broad range of PAHs via a multiple catabolic pathway.

• Journal of Microbiology
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• v.41 no.4
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• pp.349-352
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• 2003

Recent studies have shown that some of the PCB (polychlorinated biphenyl)-degraders are able to effectively degrade PCB in the presence of monoterpenes, which act as inducers for the degradation pathway. Rhodococcus sp. T104, an effective PCB degrader, has been shown to induce the degradation pathway by utilizing limonenes, cymenes, carvones, and pinenes as sole carbon sources which can be found in the natural environment. Moreover, the strain T104 proved to possess three separate oxidation pathways of limonene, biphenyl, and phenol. Of these three, the limonene can also induce the biphenyl degradation pathway. In this work, we report the presence of three distinct genes for aromatic oxygenase, which are putatively involved in the degradation of aromatic substrates including biphenyl, limonene, and phenol, through PCR amplification and denaturing gradient gel electrophoresis (DGGE). The genes were differentially expressed and well induced by limonene, cymene, and plant extract A compared to biphenyl and/or glucose. This indicates that substrate specificity must be taken into account when biodegradation of the target compounds are facilitated by the plant natural substrates.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1977.10a
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• pp.191-192
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• 1977

Microbial degradation of unnatural synthetic substances are interesting from hypothesis that a new metabolic pathway should be established from the unnatural compound to a common metabolic intermediate fro such an ability. The establishment of a new pathway essentially require a creature of new enzyme active on the unnatural synthetic compound which have never existed on the each.(중략)

• Journal of Microbiology and Biotechnology
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• v.28 no.7
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• pp.1147-1155
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• 2018

The degradation efficiency and catabolism pathways of the different methylxanthines (MXs) in isolated caffeine-tolerant strain Pseudomonas putida CT25 were comprehensively studied. The results showed that the degradation efficiency of various MXs varied with the number and position of the methyl groups on the molecule (i.e., xanthine > 7-methylxanthine ${\approx}$ theobromine > caffeine > theophylline > 1-methylxanthine). Multiple MX catabolism pathways coexisted in strain CT25, and a different pathway would be triggered by various MXs. Demethylation dominated in the degradation of N-7-methylated MXs (such as 7-methylxanthine, theobromine, and caffeine), where C-8 oxidation was the major pathway in the catabolism of 1-methylxanthine, whereas demethylation and C-8 oxidation are likely both involved in the degradation of theophylline. Enzymes responsible for MX degradation were located inside the cell. Both cell culture and cell-free enzyme assays revealed that N-1 demethylation might be a rate-limiting step for the catabolism of the MXs. Surprisingly, accumulation of uric acid was observed in a cell-free reaction system, which might be attributed to the lack of activity of uricase, a cytochrome c-coupled membrane integral enzyme.